NCERT - MOLECULAR BASIS OF INHERITANCE

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Questions and Answers

What is the total number of base pairs in bacteriophage lambda?

4600000

48502 (correct)

5386

3300000000

Uracil is found in DNA.

False

Name the two types of nitrogenous bases found in nucleotides.

Purines and Pyrimidines

A nucleotide consists of a nitrogenous base, a pentose sugar, and a __________.

phosphate group Signup and view all the answers

Match the nitrogenous bases with their categories:

Adenine = Purine Cytosine = Pyrimidine Guanine = Purine Thymine = Pyrimidine Signup and view all the answers

Which of the following links nucleotides together to form a polynucleotide chain?

3'-5' phosphodiester linkage Signup and view all the answers

Friedrich Meischer was the first to isolate DNA in its native form.

False Signup and view all the answers

What additional group is present in RNA that is not found in DNA nucleotides?

–OH group at the 2' position Signup and view all the answers

What was George Gamow's proposition about the genetic code?

The genetic code consists of three nucleotides. Signup and view all the answers

The codon is read in RNA with punctuation marks.

False Signup and view all the answers

Which three codons do not code for amino acids?

UAA, UAG, UGA Signup and view all the answers

The amino acid coded for by the codon AUG is __________.

Methionine Signup and view all the answers

What does the genetic code being 'degenerate' imply?

Some amino acids are coded by more than one codon. Signup and view all the answers

The enzymes developed by Har Gobind Khorana were used in __________ synthesis of RNA.

enzymatic Signup and view all the answers

What is the relationship between amino acids and mutations in genetic code studies?

Mutations affect the sequence of amino acids coded by genes. Signup and view all the answers

Match the following codons to their corresponding amino acids:

AUG = Methionine UUU = Phenylalanine UAA = Stop codon UAG = Stop codon Signup and view all the answers

What is the function of the anticodon loop in tRNA?

To have bases complementary to the codon Signup and view all the answers

Initiator tRNA is specific only to start codons, which signals the beginning of translation.

True Signup and view all the answers

What is the role of ATP in the process of tRNA charging?

ATP provides the energy required to activate amino acids and link them to tRNA. Signup and view all the answers

The ribosome is composed of structural RNAs and approximately _____ different proteins.

80 Signup and view all the answers

Match the following components with their functions in translation:

tRNA = Brings amino acids to the ribosome Peptide Bond = Links amino acids together Ribosome = Site of protein synthesis mRNA = Template for amino acid sequence Signup and view all the answers

What is the structural form of tRNA in its actual state?

Inverted L Signup and view all the answers

There are specific tRNAs for stop codons during the translation process.

False Signup and view all the answers

What is the purpose of the peptide bond?

To link amino acids together in a polypeptide chain. Signup and view all the answers

What is the primary purpose of cloning DNA fragments in sequencing?

To amplify each DNA fragment for easier sequencing Signup and view all the answers

Sanger's method is solely used for determining DNA sequences.

False Signup and view all the answers

What is the total estimated number of genes in the human genome?

30,000 Signup and view all the answers

The largest known human gene is __________, consisting of 2.4 million bases.

dystrophin Signup and view all the answers

What percentage of base sequences among humans are the same?

99.9% Signup and view all the answers

Match the following terms with their descriptions:

BAC = Bacterial artificial chromosomes YAC = Yeast artificial chromosomes Automated DNA sequencer = Device used for sequencing DNA fragments Microsatellites = Repetitive DNA sequences used for genetic mapping Signup and view all the answers

Chromosome 1 has the fewest number of genes among human chromosomes.

False Signup and view all the answers

Which of the following is NOT a feature of the human genome project?

The human genome consists of 5 million base pairs Signup and view all the answers

What are single nucleotide polymorphisms (SNPs)?

Single nucleotide polymorphisms are locations in the DNA where single base differences occur. Signup and view all the answers

DNA fingerprinting is a quick way to compare DNA sequences of ______ individuals.

two Signup and view all the answers

Over 50% of discovered genes have unknown functions.

True Signup and view all the answers

In what year was the sequencing of chromosome 1 completed?

2006 Signup and view all the answers

Match the following chromosomes with the correct number of genes:

Chromosome 1 = 2968 Chromosome Y = 231 Signup and view all the answers

What role do repetitive sequences play in the human genome?

They help understand chromosome structure and evolution. Signup and view all the answers

The human genome is estimated to consist of 3 billion base pairs.

True Signup and view all the answers

What is one major application of DNA sequencing mentioned?

Finding chromosomal locations for disease-associated sequences. Signup and view all the answers

What does VNTR stand for in the context of DNA fingerprinting?

Variable Number of Tandem Repeats Signup and view all the answers

DNA fingerprinting was developed by Francis Crick.

False Signup and view all the answers

What is the primary role of polymorphisms in evolution?

Polymorphisms play a crucial role in variability and speciation. Signup and view all the answers

The technique of DNA fingerprinting includes __________ as a step that involves identifying the DNA fragments.

detection of hybridised DNA fragments by autoradiography Signup and view all the answers

Match the following steps of DNA fingerprinting with their descriptions:

Isolation of DNA = Extracting DNA from the sample Electrophoresis = Separation of DNA fragments based on size Hybridisation = Binding of VNTR probe to DNA fragments Autoradiography = Visualisation of hybridised DNA fragments Signup and view all the answers

What is the maximum size of VNTR fragments that can be obtained?

20 kb Signup and view all the answers

Identical twins have the same VNTR patterns.

True Signup and view all the answers

What technique enhances the sensitivity of DNA fingerprinting?

Polymerase chain reaction (PCR) Signup and view all the answers

What is the sugar component of DNA nucleotides?

Deoxyribose Signup and view all the answers

Cytosine is found in both DNA and RNA.

True Signup and view all the answers

What type of linkage connects nucleotides in a polynucleotide chain?

Phosphodiester linkage Signup and view all the answers

A __________ is formed when a nitrogenous base is linked to a pentose sugar.

nucleoside Signup and view all the answers

Match each nitrogenous base with its category:

Adenine = Purine Thymine = Pyrimidine Guanine = Purine Cytosine = Pyrimidine Signup and view all the answers

What is the function of the 5' end of a polynucleotide chain?

It has a free phosphate group. Signup and view all the answers

Uracil replaces Thymine in RNA.

True Signup and view all the answers

Who first identified DNA as 'Nuclein'?

Friedrich Meischer Signup and view all the answers

What type of DNA replication was proposed by Watson and Crick?

Semiconservative replication Signup and view all the answers

RNA is more stable than DNA.

False Signup and view all the answers

Who were the scientists that provided experimental proof for semiconservative DNA replication?

Matthew Meselson and Franklin Stahl Signup and view all the answers

DNA's double-stranded structure allows for a process of ________ to repair changes.

repair Signup and view all the answers

What allows DNA to resist changes over time?

The double-stranded structure and chemical modifications Signup and view all the answers

Match the following scientists with their contributions to DNA research:

Watson and Crick = Proposed the double helix structure for DNA Meselson and Stahl = Conducted experiments proving semiconservative replication Franklin = Produced the famous Photo 51 Griffith = Discovered the transformation principle in bacteria Signup and view all the answers

Each DNA molecule after replication will have two newly synthesized strands.

False Signup and view all the answers

What biochemical issue did RNA face that led to the evolution of DNA?

RNA was reactive and unstable. Signup and view all the answers

What process describes the flow of genetic information in most organisms?

DNA to RNA to Protein Signup and view all the answers

The distance between two consecutive base pairs in DNA is approximately 0.34 nm.

True Signup and view all the answers

What is the name of the structure formed when DNA is packaged with histones in eukaryotic cells?

Nucleosome Signup and view all the answers

In some viruses, the flow of information is from RNA to __________.

DNA Signup and view all the answers

Match the following structures with their descriptions:

Nucleoid = Region in prokaryotes containing DNA Nucleosome = Complex of DNA and histone proteins Double helix = Structure of DNA molecule Base pair = Unit of nucleotides held together by hydrogen bonds Signup and view all the answers

How long is the DNA double helix in a typical mammalian cell?

Approximately 2.2 meters Signup and view all the answers

Histones are negatively charged proteins that assist in DNA packaging.

False Signup and view all the answers

Which two amino acids are histones rich in that contribute to their positive charge?

Lysine and Arginine Signup and view all the answers

What defines the 5' end of a transcription unit?

Promoter Signup and view all the answers

Eukaryotic genes are typically polycistronic.

False Signup and view all the answers

What term describes the sequences that do not appear in mature RNA?

Introns Signup and view all the answers

The DNA sequence coding for tRNA or rRNA also defines a ______.

gene Signup and view all the answers

Match the terms with their definitions:

Exons = Coding sequences that appear in mature RNA Introns = Non-coding sequences that are removed during RNA processing Promoter = Region that initiates transcription Terminator = Region that signals the end of transcription Signup and view all the answers

Which of the following statements is true regarding regulatory sequences?

They can affect the transcription process. Signup and view all the answers

A cistron is defined as a segment of DNA coding for a polypeptide.

True Signup and view all the answers

What are the functional units of inheritance located on DNA called?

Genes Signup and view all the answers

Which part of tRNA is responsible for binding to amino acids?

Amino acid acceptor end Signup and view all the answers

Initiator tRNA is specific only to start codons.

True Signup and view all the answers

What is the shape of the tRNA in its actual structure?

inverted L Signup and view all the answers

The process of linking amino acids by a peptide bond requires __________.

energy Signup and view all the answers

What is the role of ATP in the charging of tRNA?

It activates amino acids Signup and view all the answers

There are tRNAs for stop codons.

False Signup and view all the answers

What bond is formed between amino acids during translation?

peptide bond Signup and view all the answers

What type of DNA is primarily used as a probe in DNA fingerprinting?

Satellite DNA Signup and view all the answers

The technique of DNA fingerprinting can differentiate the DNA of monozygotic twins.

False Signup and view all the answers

Who developed the technique of DNA fingerprinting?

Alec Jeffreys Signup and view all the answers

The technique of DNA fingerprinting includes the use of __________ to detect hybridized DNA fragments.

autoradiography Signup and view all the answers

Which of the following steps is NOT part of the DNA fingerprinting process?

Transcription of DNA Signup and view all the answers

Match the following terms associated with DNA fingerprinting to their descriptions:

VNTR = Variable Number of Tandem Repeats PCR = Polymerase Chain Reaction Southern blot = Technique for transferring DNA to membranes Mini-satellite = A type of satellite DNA with shorter repeat units Signup and view all the answers

What is the size range of VNTR fragments?

0.1 to 20 kb Signup and view all the answers

The characteristic pattern of DNA is generated after hybridization using a __________ probe.

labelled VNTR Signup and view all the answers

What was the outcome when Griffith injected a mixture of heat-killed S strain and live R strain bacteria into mice?

The mice died and living S bacteria were recovered Signup and view all the answers

Proteins were determined to be the genetic material based on early experiments.

False Signup and view all the answers

What did Avery, MacLeod, and McCarty conclude was the hereditary material?

DNA Signup and view all the answers

The component that inhibits transformation when digested is __________.

DNAse Signup and view all the answers

Match the following scientists with their contributions:

Griffith = Discovered transformation in bacteria Avery, MacLeod, McCarty = Identified DNA as the hereditary material Hershey and Chase = Conducted experiments with bacteriophages to prove DNA is genetic material Chargaff = Formulated base pairing rules for DNA Signup and view all the answers

In Hershey and Chase's experiments, which radioactive element was used to label DNA?

Radioactive phosphorus Signup and view all the answers

Heat-killed S strain bacteria can cause pneumonia in infected mice.

False Signup and view all the answers

What is the primary role of the genetic material in cells?

To store and transmit genetic information Signup and view all the answers

What is the average rate of polymerization during DNA replication in E. coli?

2000 bp per second Signup and view all the answers

DNA-dependent DNA polymerases can initiate the process of replication on their own.

False Signup and view all the answers

What enzyme is responsible for joining the discontinuously synthesized fragments of DNA?

DNA ligase Signup and view all the answers

In E. coli, the region where replication originates is referred to as the __________.

origin of replication Signup and view all the answers

What occurs at the S-phase of the cell cycle?

DNA replication Signup and view all the answers

Replication in E. coli occurs continuously on both strands of DNA.

False Signup and view all the answers

The __________ is the small opening in the DNA helix where replication occurs.

replication fork Signup and view all the answers

What is the primary role of RNA in cellular functions?

Transfer and expression of genetic information Signup and view all the answers

DNA is chemically and structurally less stable than RNA.

False Signup and view all the answers

What is the primary function of the z gene in the lac operon?

Codes for beta-galactosidase Signup and view all the answers

What are the two bases that adenine pairs with in DNA?

Thymine Signup and view all the answers

During the process of ______________, exons are joined and introns are removed from the RNA transcript.

splicing Signup and view all the answers

The lac operon consists of only structural genes, with no regulatory gene present.

False Signup and view all the answers

Match the following types of RNA with their primary functions:

mRNA = Carries genetic information from DNA to ribosomes tRNA = Transfers amino acids during protein synthesis rRNA = Structural component of ribosomes snRNA = Involved in splicing of RNA Signup and view all the answers

What are the three structural genes found in the lac operon?

z, y, and a Signup and view all the answers

The operator region in prokaryotic DNA is typically regulated by the interaction of proteins with sequences termed __________.

operators Signup and view all the answers

What does the genetic code read on the principle of?

Complementarity Signup and view all the answers

Match the following lac operon components with their functions:

i gene = Codes for the repressor z gene = Codes for beta-galactosidase y gene = Codes for permease a gene = Codes for transacetylase Signup and view all the answers

In bacteria, multiple genes are regulated in units known as operons.

True Signup and view all the answers

What type of bond is responsible for the pairing between bases in the DNA double helix?

Hydrogen bonds Signup and view all the answers

Which of the following is true regarding the interaction of lactose with the lac operon?

Lactose is termed an inducer for the operon. Signup and view all the answers

The lac operator can interact with multiple types of repressor proteins.

False Signup and view all the answers

Who were the two scientists that first elucidated the lac operon?

Francois Jacob and Jacque Monod Signup and view all the answers

What initiates the translation process in mRNA?

Start codon (AUG) Signup and view all the answers

The untranslated regions (UTR) of mRNA are translated into polypeptides.

False Signup and view all the answers

What is the function of the release factor during translation?

To terminate translation and release the completed polypeptide from the ribosome. Signup and view all the answers

In eukaryotes, regulation of gene expression can occur at the __________ level.

transcriptional Signup and view all the answers

Match the following stages of protein synthesis with their descriptions:

Initiation = Ribosome binds to the start codon and begins translation Elongation = Amino acids are sequentially added to the growing polypeptide chain Termination = Release factor binds to the stop codon, ending translation Translation = Process of synthesizing proteins from mRNA Signup and view all the answers

Which of the following best describes the role of beta-galactosidase in E. coli?

It catalyzes the hydrolysis of lactose. Signup and view all the answers

The elongation phase of translation involves the ribosome moving from one codon to the next on the mRNA strand.

True Signup and view all the answers

Which RNA polymerase is responsible for the transcription of precursor mRNA?

RNA polymerase II Signup and view all the answers

Why is it necessary for cells to regulate gene expression?

To adapt to metabolic, physiological, or environmental conditions and perform specific cellular functions. Signup and view all the answers

Introns are retained in the final mRNA after the splicing process.

False Signup and view all the answers

What is added to the 5'-end of hnRNA during the capping process?

methyl guanosine triphosphate Signup and view all the answers

The fully processed hnRNA is known as __________.

mRNA Signup and view all the answers

Match the RNA polymerases with their functions:

RNA polymerase I = Transcribes rRNAs RNA polymerase II = Transcribes precursor mRNA (hnRNA) RNA polymerase III = Transcribes tRNA and other small RNAs RNA polymerase IV = N/A (not mentioned) Signup and view all the answers

What is the primary role of the genetic code?

Directs the sequence of amino acids in proteins Signup and view all the answers

The genetic code has a one-to-one correspondence between nucleotides and amino acids.

False Signup and view all the answers

Which feature of the genome does the presence of introns suggest?

ancient feature Signup and view all the answers

What type of DNA was produced after E. coli was transferred to a medium containing 14NH4Cl for one generation?

Hybrid DNA Signup and view all the answers

15N is a radioactive isotope of nitrogen.

False Signup and view all the answers

What is the main enzyme responsible for DNA synthesis in E. coli?

DNA-dependent DNA polymerase Signup and view all the answers

E. coli divides approximately every __________ minutes.

20 Signup and view all the answers

Match the following densities of DNA with the generation they represent:

Light DNA = III generation Hybrid DNA = I generation Heavy DNA = Initial culture Mixed Density DNA = II generation Signup and view all the answers

Which technique was used to separate DNA based on density in the experiments?

CsCl density gradient centrifugation Signup and view all the answers

The DNA replication process in cells is completely error-free.

False Signup and view all the answers

What experimental design proved that DNA in chromosomes replicates semiconservatively?

The use of radioactive thymidine by Taylor and colleagues in Vicia faba. Signup and view all the answers

In E. coli, replication occurs randomly at any place in the DNA.

False Signup and view all the answers

Name the enzyme that joins the discontinuously synthesized DNA fragments.

DNA ligase Signup and view all the answers

The process of DNA replication in prokaryotes occurs at the _____ phase of the cell cycle.

S-phase Signup and view all the answers

Match the following components with their functions in DNA replication:

DNA polymerases = Catalyze DNA strand synthesis Deoxyribonucleoside triphosphates = Provide energy for polymerization Replication fork = Site where DNA unwinding occurs Origin of replication = Starting point for replication Signup and view all the answers

Why is DNA replication considered an energetically expensive process?

Both B and C are correct. Signup and view all the answers

In eukaryotes, replication occurs continuously without any interruptions.

False Signup and view all the answers

What term describes the chromosomal anomaly that can occur if cell division fails after DNA replication?

polyploidy Signup and view all the answers

What distinguishes RNA from DNA in terms of nitrogenous bases?

RNA contains uracil instead of thymine found in DNA. Signup and view all the answers

Both DNA and RNA have a phosphate group in their nucleotides.

True Signup and view all the answers

List the two types of purines found in nucleotides.

Adenine and Guanine Signup and view all the answers

The backbone of a polynucleotide chain is formed by __________ and phosphates.

sugars Signup and view all the answers

Match the following elements with their respective descriptions:

Adenine = Purine Cytosine = Pyrimidine Ribose = Sugar in RNA Deoxyribose = Sugar in DNA Signup and view all the answers

How are two nucleotides linked together in a polynucleotide chain?

Through 5'-3' phosphodiester linkage. Signup and view all the answers

Thymine is present in both DNA and RNA.

False Signup and view all the answers

What is the term used for the linkage between a nitrogenous base and a pentose sugar?

N-glycosidic linkage Signup and view all the answers

What is the primary role of the lac operon in prokaryotes?

Regulating gene expression Signup and view all the answers

The lac operon is an example of a monocistronic operon.

False Signup and view all the answers

What does the i gene in the lac operon code for?

Repressor protein Signup and view all the answers

In the lac operon, lactose acts as an __________ to enable the transcription of the operon.

inducer Signup and view all the answers

Match the gene with its function in the lac operon:

z gene = Codes for beta-galactosidase y gene = Codes for permease a gene = Codes for transacetylase i gene = Codes for repressor protein Signup and view all the answers

Which of the following statements accurately describes the function of the lac repressor?

It prevents transcription when lactose is absent. Signup and view all the answers

All operons in prokaryotes are composed of an operator and a single structural gene.

False Signup and view all the answers

Who were the two scientists that elucidated the lac operon?

Francois Jacob and Jacque Monod Signup and view all the answers

What is the primary use of DNA fingerprinting?

Comparing DNA sequences for identification Signup and view all the answers

DNA polymorphism can arise from mutations in both somatic and germ cells.

True Signup and view all the answers

What are satellite DNA sequences primarily used for in DNA fingerprinting?

They exhibit high degrees of polymorphism. Signup and view all the answers

Polymorphism refers to variation at the genetic level due to __________.

mutations Signup and view all the answers

Match the types of DNA with their characteristics:

Micro-satellites = Short repetitions of DNA Mini-satellites = Medium repetitions of DNA Satellite DNA = Large regions of repeated DNA Bulk genomic DNA = Major peak in density gradient centrifugation Signup and view all the answers

In what situations is DNA fingerprinting particularly useful?

Forensic identification and paternity testing Signup and view all the answers

Micro-satellites are generally larger than mini-satellites in terms of DNA repeats.

False Signup and view all the answers

What frequency must a variant allele occur to be considered a DNA polymorphism?

Greater than 0.01 Signup and view all the answers

What is the result of a point mutation in the gene for beta globin chain?

It causes a change in the amino acid sequence from glutamate to valine. Signup and view all the answers

Insertion or deletion of one or two bases does not affect the reading frame.

False Signup and view all the answers

What condition is caused by the mutation of the beta globin gene?

Sickle cell anemia Signup and view all the answers

The process of mutations that changes the reading frame of a gene due to insertion or deletion is called __________ mutations.

frameshift Signup and view all the answers

Match the following types of mutations with their descriptions:

Point Mutation = Change of a single base pair Frameshift Mutation = Insertion or deletion of bases Insertion Mutation = Adding one or more bases to DNA Deletion Mutation = Removing one or more bases from DNA Signup and view all the answers

Which of the following best describes the role of tRNA?

It acts as an adapter molecule that reads the genetic code and binds to specific amino acids. Signup and view all the answers

TRNA was first recognized as a necessary component for reading the genetic code.

True Signup and view all the answers

When multiple bases are inserted or deleted in a gene, the ______________ will remain unchanged from that point onwards.

reading frame Signup and view all the answers

What was the result when Griffith injected a mixture of heat-killed S strain and live R strain bacteria into mice?

The mice died and living S strain bacteria were recovered. Signup and view all the answers

DNA is the hereditary material according to Griffith's experiments.

False Signup and view all the answers

What two enzymes did Avery, MacLeod, and McCarty find that did not affect the transformation of R strain bacteria?

Proteases and RNases Signup and view all the answers

The unequivocal proof that DNA is the genetic material came from the experiments of __________ and Martha Chase.

Alfred Hershey Signup and view all the answers

Match the following scientists with their contributions in proving DNA as the genetic material:

Griffith = Discovered the transformation principle Avery, MacLeod, McCarty = Identified DNA as the transforming agent Hershey and Chase = Provided conclusive evidence of DNA as genetic material Signup and view all the answers

What did DNase digestion indicate in Avery's experiments?

Transformation required the presence of DNA. Signup and view all the answers

The bacteriophage is a type of virus that infects plants.

False Signup and view all the answers

What was the biochemical compound thought to be the genetic material before Avery and his colleagues' experiments?

Protein Signup and view all the answers

What structure is formed when DNA is wrapped around histone proteins?

Nucleosome Signup and view all the answers

Euchromatin is transcriptionally inactive.

False Signup and view all the answers

How many base pairs of DNA does a typical nucleosome contain?

200 Signup and view all the answers

The __________ principle refers to the genetic material that can transform bacteria.

Transforming Signup and view all the answers

Match the following types of chromatin with their characteristics:

Euchromatin = Transcriptionally active Heterochromatin = Transcriptionally inactive Histone Octamer = Composed of eight histone molecules Non-histone Chromosomal proteins = Assist in chromatin packaging Signup and view all the answers

Who conducted experiments that led to the discovery of the transforming principle?

Frederick Griffith Signup and view all the answers

Nucleosomes are visualized under an electron microscope as a 'beads-on-string' structure.

True Signup and view all the answers

What is the bacterium that Frederick Griffith used in his experiments?

Streptococcus pneumoniae Signup and view all the answers

What type of vectors are commonly used for cloning DNA fragments in sequencing?

BAC and YAC Signup and view all the answers

The majority of discovered genes in the human genome have well-known functions.

False Signup and view all the answers

What was the last human chromosome to be sequenced, completed in May 2006?

chromosome 1 Signup and view all the answers

The total estimated number of genes in the human genome is __________.

30,000 Signup and view all the answers

Which feature of the human genome indicates that almost all nucleotide bases are the same across individuals?

Homogeneity Signup and view all the answers

Less than 2% of the human genome codes for proteins.

True Signup and view all the answers

Who developed the method for DNA sequencing that is commonly used today?

Frederick Sanger Signup and view all the answers

What is the main role of tRNA in protein synthesis?

To carry amino acids to the ribosome Signup and view all the answers

Translation begins with the binding of a charged tRNA to the ribosome.

True Signup and view all the answers

What type of bond is formed between amino acids during translation?

peptide bond Signup and view all the answers

During the charging of tRNA, amino acids are linked to their cognate tRNA in the presence of __________.

ATP Signup and view all the answers

Match the following components involved in translation with their respective functions:

tRNA = Brings amino acids to the ribosome Ribosome = Site of protein synthesis Amino acids = Building blocks of proteins Peptide bond = Links amino acids together Signup and view all the answers

Which statement about tRNA is true?

tRNA has a structure resembling a cloverleaf. Signup and view all the answers

Charged tRNAs need to be close enough to each other for peptide bond formation to occur.

True Signup and view all the answers

What is the function of the ribosome in protein synthesis?

To form peptide bonds between amino acids Signup and view all the answers

The untranslated regions (UTRs) of mRNA are only present at the 5' end.

False Signup and view all the answers

What signals the start of translation in an mRNA sequence?

Start codon (AUG) Signup and view all the answers

The enzyme beta-galactosidase is synthesized by E.coli to catalyze the hydrolysis of __________.

lactose Signup and view all the answers

Match the following levels of gene expression regulation with their descriptions:

Transcriptional = Regulation of primary transcript formation Processing = Regulation of splicing of RNA Transport = Movement of mRNA from nucleus to cytoplasm Translational = Regulation of protein synthesis Signup and view all the answers

What happens at the stop codon during translation?

Termination of protein synthesis Signup and view all the answers

The elongation phase of protein synthesis involves adding amino acids based on the codon sequence.

True Signup and view all the answers

What are the two types of codons found in mRNA?

Start codons and stop codons Signup and view all the answers

Which chromosome has the most genes in the human genome?

Chromosome 1 Signup and view all the answers

Repetitive sequences in the human genome are believed to have direct coding functions.

False Signup and view all the answers

What are single nucleotide polymorphisms commonly referred to as?

SNPs Signup and view all the answers

DNA fingerprinting is a quick way to compare the DNA sequences of different __________.

individuals Signup and view all the answers

Match the following to their descriptions:

Repetitive sequences = Do not have direct coding functions SNPs = Single-base DNA differences Chromosome 1 = Contains the most genes Chromosome Y = Contains the fewest genes Signup and view all the answers

What is one significant benefit of whole-genome sequencing?

Revolutionizing disease-associated sequence research Signup and view all the answers

The estimated number of base pairs in the human genome is __________.

3 billion Signup and view all the answers

Approximately 99.9% of base sequences among humans are identical.

True Signup and view all the answers

What is the primary reason both DNA strands are not copied during transcription?

To prevent the formation of double stranded RNA Signup and view all the answers

The template strand in a transcription unit has a 5' to 3' polarity.

False Signup and view all the answers

Which of the following components is NOT part of a nucleotide?

Amino acid Signup and view all the answers

What are the three primary regions that define a transcription unit in DNA?

Promoter, Structural gene, Terminator Signup and view all the answers

Which RNA polymerase is responsible for transcribing precursor mRNA?

RNA polymerase II Signup and view all the answers

The process of splicing involves the joining of introns and removal of exons.

False Signup and view all the answers

In transcription, adenosine complements __________ instead of thymine.

uracil Signup and view all the answers

Thymine is present in RNA in place of Uracil.

False Signup and view all the answers

What is added to the 5'-end of hnRNA during capping?

methyl guanosine triphosphate Signup and view all the answers

What is the backbone of a polynucleotide chain primarily made up of?

Sugar and phosphates Signup and view all the answers

Match the components of a transcription unit with their definitions:

Promoter = Region where transcription begins Structural gene = Region that is transcribed into RNA Terminator = Sequence that signals the end of transcription Template strand = Strand that acts as a guide for RNA synthesis Signup and view all the answers

The nitrogenous bases in nucleotides include purines and __________.

pyrimidines Signup and view all the answers

Which strand is referred to as the coding strand during transcription?

The strand with similar sequence to the RNA produced Signup and view all the answers

RNA polymerase III is responsible for transcribing __________.

tRNA Signup and view all the answers

Transcription results in the duplication of the entire DNA molecule.

False Signup and view all the answers

Match the following nitrogenous bases with their classification:

Adenine = Purine Guanine = Purine Cytosine = Pyrimidine Uracil = Pyrimidine Thymine = Pyrimidine Signup and view all the answers

Match the following RNA types with their functions:

rRNA = Forms the core of ribosome structure tRNA = Transports amino acids during translation mRNA = Carries the genetic information from DNA snRNA = Involved in splicing Signup and view all the answers

Which is true about the ends of a polynucleotide chain?

5' end has a free phosphate moiety Signup and view all the answers

What is the direction of RNA synthesis during transcription?

5' to 3' Signup and view all the answers

Which of the following processes occurs after hnRNA is transcribed?

Splicing Signup and view all the answers

The genetic code consists of codons that correspond directly to nucleotides.

False Signup and view all the answers

Phosphodiester linkages connect the 5' phosphate of one nucleotide to the 3' hydroxyl of another.

True Signup and view all the answers

Who first identified DNA and called it 'Nuclein'?

Friedrich Meischer Signup and view all the answers

What is the primary function of mRNA in eukaryotic cells?

To carry genetic information from the nucleus to the ribosome for protein synthesis. Signup and view all the answers

There are specific tRNAs for stop codons.

False Signup and view all the answers

What type of bond is formed between amino acids during protein synthesis?

peptide bond Signup and view all the answers

The process of linking amino acids to their corresponding tRNA is known as __________.

aminoacylation Signup and view all the answers

Match the following components with their roles in translation:

tRNA = Brings amino acids to the ribosome mRNA = Carries the genetic code from DNA ribosome = Facilitates peptide bond formation ATP = Provides energy for aminoacylation Signup and view all the answers

What configuration does tRNA assume in its actual structure?

Inverted L Signup and view all the answers

Translation begins with the binding of the large ribosomal subunit to mRNA.

False Signup and view all the answers

The ribosome consists of structural RNAs and about _____ different proteins.

80 Signup and view all the answers

What is the primary function of untranslated regions (UTR) in mRNA?

They ensure efficient translation. Signup and view all the answers

The ribosome only functions during the initiation phase of protein synthesis.

False Signup and view all the answers

What signal does the initiator tRNA recognize in the mRNA?

start codon (AUG) Signup and view all the answers

The enzyme __________ is synthesized by E.coli to catalyse the hydrolysis of lactose.

beta-galactosidase Signup and view all the answers

Match the following steps of translation with their descriptions:

Initiation = Ribosome binds to the start codon. Elongation = Amino acids are added sequentially to the growing polypeptide. Termination = Release factor binds to the stop codon and polypeptide is released. Signup and view all the answers

During which phase of protein synthesis does the ribosome move along the mRNA?

Elongation Signup and view all the answers

Gene expression can only be regulated at the transcriptional level in eukaryotes.

False Signup and view all the answers

What binds to the stop codon to terminate translation?

release factor Signup and view all the answers

What is the largest known human gene?

Dystrophin Signup and view all the answers

The total number of genes in the human genome is estimated to be around 50,000.

False Signup and view all the answers

What technology is commonly used to sequence DNA fragments?

Automated DNA sequencers Signup and view all the answers

Less than _____ percent of the human genome codes for proteins.

2 Signup and view all the answers

Match the following vector types to their corresponding organisms:

BAC = Yeast YAC = Bacteria Signup and view all the answers

Which of the following is a method developed by Frederick Sanger?

DNA sequencing Signup and view all the answers

Over 50% of the discovered genes have known functions.

False Signup and view all the answers

When was the sequencing of chromosome 1 completed?

May 2006 Signup and view all the answers

What type of replication process was proposed by Watson and Crick for DNA?

Semiconservative replication Signup and view all the answers

RNA is more stable than DNA due to its single-stranded structure.

False Signup and view all the answers

What does RNA act as besides serving as genetic material?

A catalyst Signup and view all the answers

DNA replication is described as __________ because the two strands separate and serve as templates.

semiconservative Signup and view all the answers

Which of the following statements about DNA structure is correct?

DNA consists of two complementary strands. Signup and view all the answers

What was the year when Meselson and Stahl conducted their experiment on DNA replication?

1958 Signup and view all the answers

DNA's double stranded structure makes it more reactive than RNA.

False Signup and view all the answers

DNA polymerases can initiate the replication process on their own.

False Signup and view all the answers

What enzymes are responsible for joining discontinuously synthesized fragments during DNA replication?

DNA ligase Signup and view all the answers

The two strands of DNA cannot be separated in their entire length due to high energy requirement, leading to the formation of a __________.

replication fork Signup and view all the answers

Match the following processes or components with their descriptions:

DNA polymerases = Catalyze polymerization of DNA Deoxyribonucleoside triphosphates = Provide energy for DNA synthesis Origin of replication = Definite region where replication starts DNA ligase = Joins Okazaki fragments Signup and view all the answers

During DNA replication, which strand is synthesized continuously?

Leading strand Signup and view all the answers

The S-phase of the cell cycle is when DNA replication occurs in eukaryotes.

True Signup and view all the answers

Why do deoxyribonucleoside triphosphates serve a dual purpose during DNA replication?

They act as substrates for polymerization and provide energy for the reaction. Signup and view all the answers

What is the role of the ribosome during translation?

To catalyze the formation of peptide bonds Signup and view all the answers

The untranslated regions (UTR) are only present at the 5' end of mRNA.

False Signup and view all the answers

What codon serves as the start signal for translation?

AUG Signup and view all the answers

The __________ factor binds to the stop codon to terminate translation.

release Signup and view all the answers

Match the following processes with their respective levels of gene expression regulation:

Transcriptional level = Formation of primary transcript Processing level = Regulation of splicing Transport = Movement of mRNA from nucleus to cytoplasm Translational level = Regulation during protein synthesis Signup and view all the answers

Which event occurs after the ribosome binds to the start codon?

Elongation phase begins Signup and view all the answers

Gene expression can only be regulated at the transcriptional level.

False Signup and view all the answers

How does the presence or absence of lactose affect the synthesis of beta-galactosidase in E.coli?

If lactose is present, E.coli synthesizes beta-galactosidase; if not, synthesis stops. Signup and view all the answers

The technique of DNA fingerprinting relies on the consistent size of VNTR across individuals.

False Signup and view all the answers

Name one application of DNA fingerprinting other than forensic science.

Paternity testing, genetic studies, or population genetics. Signup and view all the answers

The five steps in DNA fingerprinting include isolation of DNA, digestion by restriction endonucleases, __________, blotting of separated DNA fragments, and hybridization using labelled VNTR probe.

separation of DNA fragments by electrophoresis Signup and view all the answers

Match the following steps of the DNA fingerprinting process with their descriptions:

Isolation of DNA = Extracting DNA from cells Digestion by restriction endonucleases = Cutting DNA into smaller fragments Separation by electrophoresis = Sorting DNA fragments by size Hybridization using VNTR probe = Attaching a labeled probe to DNA fragments Signup and view all the answers

What type of DNA sequence does VNTR belong to?

Mini-satellite Signup and view all the answers

Identical twins have different VNTR patterns.

False Signup and view all the answers

What enhances the sensitivity of DNA fingerprinting?

Polymerase chain reaction (PCR). Signup and view all the answers

Which molecule is primarily responsible for transferring genetic information from DNA to proteins?

RNA Signup and view all the answers

Introns are coding sequences that are joined together during RNA splicing.

False Signup and view all the answers

What is the process called that synthesizes RNA from a DNA template?

Transcription Signup and view all the answers

The _____ bonds between nitrogenous bases in DNA strands contribute to its double helical structure.

hydrogen Signup and view all the answers

Match the following processes with their descriptions:

Transcription = Synthesis of RNA from a DNA template Translation = Synthesis of proteins from mRNA Splicing = Removing introns and joining exons Replication = Copying of DNA strands Signup and view all the answers

The lac operator is present in all operons.

False Signup and view all the answers

What is the function of the tRNA during translation?

It carries amino acids to the ribosome Signup and view all the answers

What type of proteins regulate the activity of RNA polymerase at a promoter?

Regulatory proteins Signup and view all the answers

In eukaryotes, the mRNA is immediately functional after transcription.

False Signup and view all the answers

A segment of DNA that codes for RNA is referred to as a __________.

gene Signup and view all the answers

Lactose acts as an __________ for the lac operon.

inducer Signup and view all the answers

Match the following components of the lac operon with their roles:

i gene = Codes for the repressor z gene = Codes for beta-galactosidase y gene = Codes for permease a gene = Encodes transacetylase Signup and view all the answers

What type of arrangement is observed in an operon?

Polycistronic with a common promoter Signup and view all the answers

The repressor protein interacts specifically with operator sequences.

True Signup and view all the answers

Who were the first to elucidate the transcriptionally regulated system in the lac operon?

Francois Jacob and Jacque Monod Signup and view all the answers

Which phase of protein synthesis involves the ribosome moving along the mRNA and adding amino acids sequentially?

Elongation Signup and view all the answers

The untranslated regions (UTR) of mRNA are not required for the translation process.

False Signup and view all the answers

The ribosome is primarily made up of __________ and proteins.

rRNA Signup and view all the answers

Which of the following factors does NOT influence the regulation of gene expression?

Temperature only Signup and view all the answers

The release factor binds to the start codon to initiate translation.

False Signup and view all the answers

What enzyme is synthesized by E. coli to catalyze the hydrolysis of lactose?

beta-galactosidase Signup and view all the answers

Which molecule acts as a template for RNA synthesis during transcription?

DNA Signup and view all the answers

The genetic code is read in sets of four nucleotides to code for amino acids.

False Signup and view all the answers

What type of RNA molecule aids in the transfer of amino acids during protein synthesis?

tRNA Signup and view all the answers

In eukaryotes, non-coding sequences called __________ are removed during RNA processing.

introns Signup and view all the answers

Match the following components of transcription and their functions:

mRNA = Carries genetic information from DNA RNA polymerase = Enzyme that synthesizes RNA Promoter = Sequence that signals the start of transcription Exons = Coding sequences in genes Signup and view all the answers

Which of the following statements about the structure of DNA is true?

Adenine pairs with Thymine through two hydrogen bonds. Signup and view all the answers

Translation occurs in the nucleus of eukaryotic cells.

False Signup and view all the answers

What is the primary purpose of transcription in gene expression?

To synthesize RNA from a DNA template Signup and view all the answers

What replaces thymine in RNA during transcription?

Uracil Signup and view all the answers

Both strands of DNA are copied during transcription.

False Signup and view all the answers

What are the three main components of a transcription unit?

Promoter, Structural gene, Terminator Signup and view all the answers

During transcription, the strand of DNA that acts as the template is oriented in the ________ direction.

3' to 5' Signup and view all the answers

Match the following regions of a transcription unit with their functions:

Promoter = Initiates transcription Structural gene = Contains the coding sequence Terminator = Signals the end of transcription Signup and view all the answers

Why does the production of two complementary RNA molecules complicate genetic information transfer?

It may create two different proteins from the same segment of DNA. Signup and view all the answers

The coding strand of DNA has the same sequence as RNA, except for thymine.

True Signup and view all the answers

What is the primary role of the promoter in the transcription unit?

To initiate transcription Signup and view all the answers

What type of model did Watson and Crick propose for the structure of DNA?

Double helix model Signup and view all the answers

Adenine pairs with Guanine in the structure of DNA.

False Signup and view all the answers

What is the length of the pitch of the DNA helix?

3.4 nm Signup and view all the answers

The two strands of DNA run in __________ polarity.

anti-parallel Signup and view all the answers

What is the role of permease in bacteria when lactose is present?

It transports lactose into the cells. Signup and view all the answers

Match the base pairs with the correct number of hydrogen bonds:

Adenine and Thymine = Three hydrogen bonds Guanine and Cytosine = Two hydrogen bonds Signup and view all the answers

Which base pairing is correct based on the DNA structure?

Adenine pairs with Thymine Signup and view all the answers

Glucose can act as an inducer for the lac operon.

False Signup and view all the answers

What is the estimated total cost of the Human Genome Project at $3 per base pair?

$9 billion Signup and view all the answers

Watson and Crick’s model explained the mechanism of DNA replication.

True Signup and view all the answers

The human genome is estimated to have approximately __________ base pairs.

3 billion Signup and view all the answers

What observation by Erwin Chargaff contributed to the understanding of DNA structure?

The ratios between Adenine and Thymine, and Guanine and Cytosine are constant and equal to one. Signup and view all the answers

Match the following components of the lac operon with their functions:

Repressor = Prevents transcription in the absence of an inducer Inducer = Inactivates the repressor RNA polymerase = Transcribes the operon Operator = Binding site for the repressor Signup and view all the answers

Which of the following statements is true regarding the regulation of the lac operon?

It is regulated by both a repressor and transcription factors. Signup and view all the answers

The lac operon is expressed for a long duration when lactose is present in the medium.

True Signup and view all the answers

In what year was the Human Genome Project launched?

1990 Signup and view all the answers

Which chromosome has the most genes?

Chromosome 1 Signup and view all the answers

Single nucleotide polymorphisms (SNPs) represent differences in DNA sequences that can affect phenotypic traits.

True Signup and view all the answers

What is the estimated total size of the human genome in base pairs?

3 billion Signup and view all the answers

Repetitive sequences are thought to have no direct coding functions, but they provide insight into chromosome __________ and dynamics.

structure Signup and view all the answers

Match each term with its description:

SNPs = Single nucleotide variations DNA fingerprinting = Comparing DNA sequences for individual identification Chromosome 1 = Chromosome with the most genes Repetitive sequences = DNA sequences repeated multiple times Signup and view all the answers

What is a major benefit of the human genome sequence?

It revolutionizes the approach to biological research. Signup and view all the answers

Identical twins have different DNA sequences.

False Signup and view all the answers

What type of variations can SNPs cause in individuals?

Genetic differences Signup and view all the answers

What was used as the only nitrogen source for E. coli in the experiment?

15NH4Cl Signup and view all the answers

The DNA synthesized with 15N can be separated from normal DNA by differences in their radioactivity.

False Signup and view all the answers

What density of DNA is produced after E. coli undergoes one generation in the presence of 14NH4Cl?

Hybrid density Signup and view all the answers

The main enzyme involved in DNA replication is called DNA-dependent DNA __________.

polymerase Signup and view all the answers

Match the following descriptions with the corresponding terms:

15N = Heavy isotope of nitrogen used in the experiment 14N = Normal nitrogen isotope used after transfer CsCl = Substance used for density gradient centrifugation E. coli = Bacterium used in the DNA replication study Signup and view all the answers

After how many minutes of growth in 14NH4Cl does E. coli produce equal amounts of hybrid and light DNA?

40 minutes Signup and view all the answers

The experiments conducted by Taylor and his colleagues confirmed that DNA replicates in a conservative manner.

False Signup and view all the answers

What is the role of DNA-dependent DNA polymerase in living cells?

Catalyzes the polymerization of deoxynucleotides Signup and view all the answers

How many codons code for amino acids in the genetic code?

61 Signup and view all the answers

The codon AUG serves only one purpose as a start codon.

False Signup and view all the answers

What technique was used by Har Gobind Khorana to synthesize RNA molecules?

Chemical method for synthesizing RNA with defined combinations of bases. Signup and view all the answers

Three codons UAA, UAG, and UGA function as __________ codons.

stop Signup and view all the answers

Match the codons with their corresponding amino acids:

AUG = Methionine UUU = Phenylalanine UAA = Stop UAG = Stop Signup and view all the answers

What characteristic of the genetic code indicates that some amino acids may be represented by more than one codon?

Degeneracy of the code Signup and view all the answers

The genetic code is universally conserved across all species without any exceptions.

False Signup and view all the answers

What are the two primary properties of the genetic code learned from the provided content?

The codon is a triplet and the code is degenerate. Signup and view all the answers

What are the two commonly used hosts for cloning DNA fragments?

Bacteria and yeast Signup and view all the answers

The sequence of chromosome 1 was completed in December 2005.

False Signup and view all the answers

Name the largest known human gene.

dystrophin Signup and view all the answers

The human genome contains approximately __________ million base pairs.

3164.7 Signup and view all the answers

What percentage of the human genome is estimated to code for proteins?

2% Signup and view all the answers

Almost all nucleotide bases in humans are identical, differing by only 0.1%.

True Signup and view all the answers

How many genes are estimated to exist in the human genome?

30,000 Signup and view all the answers

Which chromosome has the most number of genes in humans?

Chromosome 1 Signup and view all the answers

Repetitive sequences in the human genome are thought to have direct coding functions.

False Signup and view all the answers

What is the estimated total number of base pairs in the human genome?

3 billion Signup and view all the answers

DNA fingerprinting is a technique that quickly compares the DNA sequences of ______ individuals.

two Signup and view all the answers

How many single nucleotide differences (SNPs) are estimated to exist in the human genome?

1.4 million Signup and view all the answers

The majority of the human genome consists of unique sequences.

False Signup and view all the answers

What is one of the main applications of sequencing the human genome?

Finding chromosomal locations for disease-associated sequences Signup and view all the answers

DNA replication in E.coli occurs in both directions simultaneously.

False Signup and view all the answers

The correct direction of DNA polymerisation is from _ to _ (indicate the polarity).

5', 3' Signup and view all the answers

Match the following components with their roles in DNA replication:

DNA polymerase = Catalyses the polymerisation of DNA Replication fork = Site where DNA strands separate Origin of replication = Specific site where replication begins Deoxyribonucleoside triphosphate = Substrate and energy source for polymerisation Signup and view all the answers

What is the role of deoxyribonucleoside triphosphates in DNA replication?

As both substrates and energy sources Signup and view all the answers

Replication in Eukaryotes occurs during the G-phase of the cell cycle.

False Signup and view all the answers

What is a consequence of a failure in cell division after DNA replication?

Polyploidy Signup and view all the answers

What is the primary role of the repressor in the lac operon?

To prevent RNA polymerase from transcribing the operon Signup and view all the answers

What is the total estimated cost of sequencing the human genome based on the initial estimate of $3 per base pair?

9 billion US dollars Signup and view all the answers

The initial year when the Human Genome Project was launched is __________.

1990 Signup and view all the answers

Which of the following is NOT considered an inducer for the lac operon?

Glucose Signup and view all the answers

The repressor of the lac operon is synthesized only in response to lactose.

False Signup and view all the answers

What is the estimated number of base pairs in the human genome?

Approximately 3 billion Signup and view all the answers

What does the Central dogma of molecular biology describe?

DNA to RNA to Protein Signup and view all the answers

What is the name of the process where genetic information flows from RNA to DNA in some viruses?

Reverse transcription Signup and view all the answers

In prokaryotes like E. coli, DNA is organized in a region termed the __________.

nucleoid Signup and view all the answers

Match the following components with their descriptions:

Histones = Basic proteins that package DNA in eukaryotes Nucleoid = Region where prokaryotic DNA is located DNA = Molecule that carries genetic information RNA = Transcribes genetic data for protein synthesis Signup and view all the answers

Which amino acids are histones rich in?

Lysine and Arginine Signup and view all the answers

In eukaryotic cells, the packaging of DNA is less complex than in prokaryotic cells.

False Signup and view all the answers

What structure is formed by the wrapping of negatively charged DNA around positively charged histone octamers?

Nucleosome Signup and view all the answers

Euchromatin is transcriptionally inactive chromatin.

False Signup and view all the answers

What genetic material did Frederick Griffith study in his experiments?

Streptococcus pneumoniae Signup and view all the answers

The repeating unit of chromatin is called a __________.

nucleosome Signup and view all the answers

Match the types of chromatin to their characteristics:

Euchromatin = Transcriptionally active Heterochromatin = Transcriptionally inactive Signup and view all the answers

How many base pairs of DNA are typically contained in a nucleosome?

200 bp Signup and view all the answers

What forms the backbone of the DNA structure?

Sugar-phosphate Signup and view all the answers

NHC proteins are primarily associated with the formation of nucleosomes.

False Signup and view all the answers

Who is credited with the discovery of nuclein?

Friedrich Meischer Signup and view all the answers

Adenine pairs with Cytosine in the DNA structure.

False Signup and view all the answers

What is the distance between each base pair in the DNA double helix?

0.34 nm Signup and view all the answers

The two strands of DNA are __________ to each other.

anti-parallel Signup and view all the answers

Match the DNA base pairs with their corresponding hydrogen bonds:

Adenine - Thymine = Two hydrogen bonds Guanine - Cytosine = Three hydrogen bonds Thymine - Adenine = Two hydrogen bonds Cytosine - Guanine = Three hydrogen bonds Signup and view all the answers

What is the pitch of the DNA helix?

3.4 nm Signup and view all the answers

The Double Helix model was proposed before the year 1950.

False Signup and view all the answers

Who provided the X-ray diffraction data that helped in proposing the Double Helix model?

Maurice Wilkins and Rosalind Franklin Signup and view all the answers

What is the primary role of the lac operon?

Metabolism of lactose Signup and view all the answers

The z gene in the lac operon codes for a repressor protein.

False Signup and view all the answers

What does the term 'inducer' refer to in the context of the lac operon?

Lactose Signup and view all the answers

The i gene in the lac operon encodes a __________.

repressor Signup and view all the answers

Match the following genes in the lac operon with their functions:

i gene = Codes for the repressor z gene = Codes for beta-galactosidase y gene = Codes for permease a gene = Codes for transacetylase Signup and view all the answers

Regulatory proteins can act in which two ways?

As activators and repressors Signup and view all the answers

Operators are found only in eukaryotic gene regulation.

False Signup and view all the answers

The lac operator specifically binds the __________ protein.

lac repressor Signup and view all the answers

The genetic code is read in a discontinuous fashion.

False Signup and view all the answers

What is the function of the codon AUG in the genetic code?

It codes for Methionine and acts as the initiator codon. Signup and view all the answers

There are _____ stop codons in the genetic code.

3 Signup and view all the answers

What was the conclusion drawn by Griffith regarding the R strain bacteria after experimenting with heat-killed S strain bacteria?

The R strain bacteria became virulent. Signup and view all the answers

Who developed the enzymatic synthesis method for RNA with defined sequences?

Severo Ochoa Signup and view all the answers

Avery and his colleagues determined that DNA is the hereditary material through their experiments.

True Signup and view all the answers

What does it mean for the genetic code to be degenerate?

It means that some amino acids are coded by more than one codon. Signup and view all the answers

What did Hershey and Chase use to label the genetic material of bacteriophages in their experiment?

Radioactive phosphorus and radioactive sulfur Signup and view all the answers

The heat-killed S strain bacteria were unable to __________ the mice when injected alone.

kill Signup and view all the answers

The genetic code is universal across all forms of life.

False Signup and view all the answers

Match the following researchers with their contributions to the understanding of genetic material:

Griffith = Discovered transformation in bacteria Avery = Identified DNA as the transforming principle Hershey and Chase = Confirmed DNA as genetic material using bacteriophages Herschel = Developed the first cloning technique Signup and view all the answers

Which of the following enzymes inhibited transformation, suggesting the role of DNA?

DNase Signup and view all the answers

The transforming principle identified by Avery and his team was shown to be a protein.

False Signup and view all the answers

What is one reason some biologists were initially skeptical about DNA being the genetic material?

They believed proteins were more complex and a better candidate for genetic material. Signup and view all the answers

What is the primary function of histones in eukaryotic cells?

To package DNA into a compact structure Signup and view all the answers

What is the name of the region in prokaryotic cells where DNA is organized?

Nucleoid Signup and view all the answers

In some viruses, the genetic information flows from RNA to __________.

DNA Signup and view all the answers

Match the following molecules with their roles:

Histones = Packaging DNA DNA = Genetic information storage RNA = Protein synthesis template Proteins = Catalysts for biochemical reactions Signup and view all the answers

What is the approximate length of DNA in a typical mammalian cell?

2.2 meters Signup and view all the answers

E. coli DNA is not organized within a defined nucleus.

True Signup and view all the answers

What basic amino acids are histones rich in?

Lysine and Arginine Signup and view all the answers

In the Hershey-Chase experiment, which component of the virus was determined to be the genetic material?

Radioactive DNA Signup and view all the answers

RNA serves as the genetic material in most organisms.

False Signup and view all the answers

What are the two chemical differences between DNA and RNA?

DNA contains deoxyribose sugar and thymine, while RNA contains ribose sugar and uracil. Signup and view all the answers

A molecule that can act as genetic material must fulfill criteria for replication, stability, mutation, and expression of __________ characters.

Mendelian Signup and view all the answers

Which of the following correctly states the role of DNA in organisms?

DNA serves as the genetic blueprint for inheritance Signup and view all the answers

Proteins are considered essential genetic material in all living organisms.

False Signup and view all the answers

What did the results of the Hershey-Chase experiment conclude about the transfer of genetic material?

The experiment concluded that DNA is the genetic material passed from viruses to bacteria. Signup and view all the answers

What process was proposed by Watson and Crick for DNA replication?

Semiconservative replication Signup and view all the answers

RNA serves both as genetic material and a catalyst.

True Signup and view all the answers

What is the primary reason DNA is more stable than RNA?

DNA's double-stranded structure Signup and view all the answers

During DNA replication, each new DNA molecule contains one _______ strand and one newly synthesized strand.

parental Signup and view all the answers

What type of method was used by Meselson and Stahl to prove semiconservative replication?

Density gradient centrifugation Signup and view all the answers

What characteristic of DNA helps it resist changes?

Repair mechanisms Signup and view all the answers

DNA replication creates two identical double-stranded DNA molecules each containing both original strands.

False Signup and view all the answers

What is the start codon in mRNA that signals the beginning of translation?

AUG Signup and view all the answers

Untranslated regions (UTR) are present only at the 5' end of mRNA.

False Signup and view all the answers

What role does the release factor play in translation?

Terminates translation and releases the complete polypeptide from the ribosome. Signup and view all the answers

The sequence of mRNA that codes for a polypeptide is flanked by the start codon (AUG) and the __________.

stop codon Signup and view all the answers

What is a function of the ribosome during protein synthesis?

It catalyzes peptide bond formation Signup and view all the answers

In eukaryotes, gene expression can only be regulated at the transcriptional level.

False Signup and view all the answers

The enzyme that catalyzes the hydrolysis of lactose into galactose and glucose is called __________.

beta-galactosidase Signup and view all the answers

Which RNA polymerase is responsible for transcribing mRNA?

RNA polymerase II Signup and view all the answers

Splicing is the process by which exons are removed from the primary transcript.

False Signup and view all the answers

What unusual nucleotide is added during the capping of hnRNA?

methyl guanosine triphosphate Signup and view all the answers

A fully processed hnRNA that is transported out of the nucleus is called __________.

mRNA Signup and view all the answers

What is the primary process that allows for the removal of introns from the primary transcript?

Splicing Signup and view all the answers

The genetic code has a direct complementarity between nucleotides and amino acids.

False Signup and view all the answers

What is the significance of the presence of introns in the genetic arrangement?

It suggests an ancient feature of the genome. Signup and view all the answers

What is found in the human genome that contributes to genetic variability?

Single nucleotide polymorphisms (SNPs) Signup and view all the answers

The total estimated cost of the Human Genome Project was approximately _____ billion US dollars.

9 Signup and view all the answers

What methods enabled the Human Genome Project to become a possibility?

Development of genetic engineering techniques Signup and view all the answers

Which nucleic acid is preferred for the storage of genetic information due to its stability?

DNA Signup and view all the answers

RNA is chemically less reactive than DNA.

False Signup and view all the answers

What was the first genetic material according to the discussed theories?

RNA Signup and view all the answers

DNA and RNA both have the ability to __________.

mutate Signup and view all the answers

Match the following properties with the correct nucleic acids:

DNA = Less reactive and structurally more stable RNA = Mutates at a faster rate Both DNA and RNA = Can function as genetic material Signup and view all the answers

What chemical group contributes to the lability of RNA?

2'-OH group Signup and view all the answers

Thymine in DNA does not improve its stability compared to uracil in RNA.

True Signup and view all the answers

What role does RNA play in the synthesis of proteins?

Directly codes for proteins Signup and view all the answers

What did the Hershey-Chase experiment confirm as the genetic material?

DNA Signup and view all the answers

Proteins can serve as the genetic material in viruses.

False Signup and view all the answers

A genetic material must fulfill the criteria of being able to generate its __________.

replica Signup and view all the answers

Match the following criteria for genetic material with their descriptions:

Replication = Ability to make copies of itself Chemical stability = Resilience against chemical degradation Mutation = Capability for gradual changes over time Mendelian characters = Expression of traits in offspring Signup and view all the answers

Which type of genetic material is found in some viruses?

RNA Signup and view all the answers

Only DNA has the ability to direct its duplication.

True Signup and view all the answers

The material that passed from the virus to the bacteria was radioactive __________.

DNA Signup and view all the answers

What process describes how DNA serves as a template to create new strands?

Semiconservative replication Signup and view all the answers

RNA is more stable than DNA in terms of genetic information storage.

False Signup and view all the answers

What year did Meselson and Stahl perform their key experiment on DNA replication?

1958 Signup and view all the answers

DNA evolved from RNA due to its __________ nature.

unstable Signup and view all the answers

Match the scientists with their contributions to the understanding of DNA.

Watson and Crick = Proposed the double helical structure of DNA Meselson and Stahl = Demonstrated semiconservative DNA replication Franklin = Provided X-ray diffraction images of DNA Avery = Identified DNA as the genetic material Signup and view all the answers

Which feature of DNA contributes to its ability to repair itself?

Complementary strands Signup and view all the answers

DNA replication is proven to occur in higher organisms such as plants and humans.

True Signup and view all the answers

In semiconservative DNA replication, each new molecule contains one __________ and one newly synthesized strand.

parental strand Signup and view all the answers

What is the primary role of DNA in most organisms?

Serving as genetic material Signup and view all the answers

What is the primary use of BAC and YAC vectors in sequencing?

To clone and amplify DNA fragments Signup and view all the answers

RNA is primarily responsible for storing genetic information in most organisms.

False Signup and view all the answers

The human genome consists of over 30,000 genes, with 99.9 percent of nucleotide bases being the same in all people.

True Signup and view all the answers

What are the two types of nucleic acids found in living systems?

DNA and RNA Signup and view all the answers

What significant process was developed by Frederick Sanger?

DNA sequencing Signup and view all the answers

The complete nucleotide sequence of the human ______ has set in a new era of genomics.

genome Signup and view all the answers

Match the following roles with their corresponding nucleic acids:

DNA = Genetic material in most organisms RNA = Messenger and additional roles mRNA = Template for protein synthesis tRNA = Brings amino acids to the ribosome Signup and view all the answers

The largest known human gene is __________, which contains 2.4 million bases.

dystrophin Signup and view all the answers

Match the following types of DNA hosts with their respective vectors:

Bacteria = BAC Yeast = YAC Signup and view all the answers

Which of the following describes the structure of DNA?

A double helix of deoxyribonucleotides Signup and view all the answers

Which of the following statements accurately describes the human genome?

More than half of the discovered genes have unknown functions. Signup and view all the answers

Transcription is the process of synthesizing RNA from DNA.

True Signup and view all the answers

Human chromosome 1 was the first chromosome to be sequenced.

False Signup and view all the answers

Nucleotides are linked together to form a long polymer known as ______.

nucleic acid Signup and view all the answers

What technological advancement was required to align the sequences from DNA fragments?

Specialized computer programs Signup and view all the answers

What is the primary function of the ribosome in the process of translation?

To form peptide bonds between amino acids Signup and view all the answers

UTRs are translated into proteins during protein synthesis.

False Signup and view all the answers

What initiates the binding of the ribosome to the mRNA during the translation process?

Start codon (AUG) Signup and view all the answers

The enzyme beta-galactosidase in E.coli is synthesized to catalyze the hydrolysis of __________.

lactose Signup and view all the answers

Which of the following is NOT a level of gene expression regulation in eukaryotes?

Cell division level Signup and view all the answers

Release factors bind to stop codons to initiate the translation process.

False Signup and view all the answers

Why is the regulation of gene expression important during embryonic development?

To coordinate the expression of sets of genes for proper development Signup and view all the answers

What is the average rate of polymerization during E. coli DNA replication?

2000 bp per second Signup and view all the answers

DNA ligase is responsible for initiating the process of DNA replication.

False Signup and view all the answers

What process occurs at the origin of replication in DNA?

DNA replication Signup and view all the answers

The two terminal phosphates in a deoxynucleoside triphosphate are __________ phosphates.

high-energy Signup and view all the answers

Match the following enzymes with their functions in DNA replication:

DNA polymerase = Synthesizes new DNA strands DNA ligase = Joins Okazaki fragments Helicase = Unwinds the DNA double helix Primase = Creates RNA primers Signup and view all the answers

Replication in the E. coli DNA occurs randomly at any location along the DNA.

False Signup and view all the answers

What chromosome anomaly occurs if cell division fails after DNA replication?

polyploidy Signup and view all the answers

What technique is used to find variations in individuals at the DNA level?

DNA Fingerprinting Signup and view all the answers

The Human Genome Project aimed to sequence every base in the chicken genome.

False Signup and view all the answers

What is the main function of the lac operon in bacteria?

To regulate the metabolism of lactose Signup and view all the answers

The sequence of the complementary DNA strand to 5' -ATGCATGC-3' is __________.

3' -TACGTACG-5' Signup and view all the answers

Why does the lac operon shut down after some time following the addition of lactose?

The lactose is consumed Signup and view all the answers

What was one significant outcome of the Human Genome Project?

Identification of genetic diseases Signup and view all the answers

During translation, ribosomes play an essential role in __________.

protein synthesis Signup and view all the answers

What material served as genetic material in the Hershey-Chase experiment?

DNA Signup and view all the answers

Radioactive proteins entered the bacteria in the Hershey-Chase experiment.

False Signup and view all the answers

A molecule that can serve as genetic material must be able to undergo __________.

Replication Signup and view all the answers

Match the following viral types with their genetic material:

Tobacco Mosaic Virus = RNA QB Bacteriophage = RNA Bacteriophage Lambda = DNA Adenovirus = DNA Signup and view all the answers

Which of the following characteristics is NOT required for a genetic material?

Ability to perform enzymatic functions Signup and view all the answers

DNA is the only genetic material found in all organisms.

False Signup and view all the answers

In the Hershey-Chase experiment, the viral coats were removed from the bacteria using a __________.

blender Signup and view all the answers

What is the range of sizes for Variable Number of Tandem Repeats (VNTR)?

0.1 to 20 kb Signup and view all the answers

DNA fingerprinting can produce different patterns for identical twins.

False Signup and view all the answers

The technique of DNA fingerprinting relies heavily on ________ as a probe that indicates high polymorphism.

VNTR Signup and view all the answers

Which of these steps is NOT a part of the DNA fingerprinting process?

Digestion by RNA polymerase Signup and view all the answers

A higher degree of polymorphism in DNA enhances the uniqueness of DNA fingerprints.

True Signup and view all the answers

What causes the repressor of the lac operon to be inactivated?

Lactose Signup and view all the answers

What system regulates the expression of the lac operon?

Negative regulation Signup and view all the answers

The estimated cost of the Human Genome Project was approximately _____ billion US dollars.

9 Signup and view all the answers

Match the following components involved in the lac operon with their functions:

Lactose = Inducer that inactivates the repressor Repressor = Binds to the operator to prevent transcription RNA polymerase = Enzyme that transcribes the operon Permease = Transport protein for lactose entry Signup and view all the answers

Glucose is an effective inducer for the lac operon.

False Signup and view all the answers

Approximately how many base pairs does the human genome contain?

3 x 10^9 Signup and view all the answers

What is the primary purpose of using cloning vectors like BAC and YAC in sequencing?

To amplify the cloned DNA fragments Signup and view all the answers

The average size of a human gene is approximately 1,500 bases.

False Signup and view all the answers

What does the term 'polymorphism' refer to in the context of the human genome?

Variations in DNA sequences among individuals. Signup and view all the answers

The last of the 24 human chromosomes to be sequenced was chromosome ______.

1 Signup and view all the answers

Which of the following statements about the human genome is correct?

Less than 1% of the genome is protein-coding. Signup and view all the answers

Who developed the method used for sequencing that the automated DNA sequencers utilize?

Frederick Sanger Signup and view all the answers

It is estimated that the human genome contains 40,000 to 70,000 genes.

False Signup and view all the answers

The DNA polymerases can initiate the process of replication on their own.

False Signup and view all the answers

What are the small openings in the DNA helix where replication occurs called?

replication fork Signup and view all the answers

Deoxyribonucleoside triphosphates serve dual purposes as substrates and provide __________ for polymerization reactions.

energy Signup and view all the answers

Match the following components involved in DNA replication with their functions:

DNA polymerase = Catalyzes the polymerization of nucleotides DNA ligase = Joins discontinuous DNA fragments Replication fork = Site of ongoing DNA replication Origin of replication = Region where replication starts Signup and view all the answers

What happens if there is a failure in cell division after DNA replication?

Polyploidy may result Signup and view all the answers

In E. coli, the replication process is discontinuous on both strands of DNA.

False Signup and view all the answers

What is the primary structure of tRNA described as?

Clover-leaf Signup and view all the answers

TRNA has specific anticodons for each amino acid.

True Signup and view all the answers

What is the process of attaching the correct amino acid to the tRNA called?

Charging or aminoacylation of tRNA Signup and view all the answers

The bond that links amino acids in a polypeptide is known as a __________.

peptide bond Signup and view all the answers

What molecule is required for the charging of tRNA?

ATP Signup and view all the answers

There are tRNAs specifically for stop codons.

False Signup and view all the answers

What type of bonding is favored energetically when charged tRNAs come close together?

Peptide bond formation Signup and view all the answers

What is the result of a classical example of point mutation in the beta globin chain?

Glutamate is replaced by Valine Signup and view all the answers

Frameshift mutations occur when the reading frame of DNA is altered due to the insertion or deletion of one or two bases.

True Signup and view all the answers

The insertion of three or more bases results in a mutation that does not alter the _________ from that point onward.

reading frame Signup and view all the answers

The Human Genome Project aimed to sequence every gene in the human genome.

False Signup and view all the answers

What happens when one or two bases are inserted or deleted from a gene?

The reading frame is shifted Signup and view all the answers

Francis Crick is credited with the discovery of tRNA as an adapter molecule needed to read the genetic code.

True Signup and view all the answers

What is the technique used to analyze variations in individuals of a population at the DNA level?

DNA Fingerprinting Signup and view all the answers

What is sickle cell anemia caused by?

A point mutation that changes a single base pair in the gene for the beta globin chain. Signup and view all the answers

The process by which complementary strands of DNA are formed during replication is known as __________.

semi-conservative replication Signup and view all the answers

Match the following nucleic acids with their functions:

mRNA = Transmits genetic information from DNA to ribosomes tRNA = Brings amino acids to ribosomes during translation rRNA = Forms the core of ribosome's structure DNA = Stores genetic information Signup and view all the answers

Why does the lac operon shut down some time after the addition of lactose?

Both A and C Signup and view all the answers

DNA fingerprinting is solely used in forensic science.

False Signup and view all the answers

What type of polymerase synthesizes RNA from a DNA template?

RNA polymerase Signup and view all the answers

Which of the following is a commonly used vector in cloning DNA fragments?

BAC Signup and view all the answers

The total number of genes in the human genome is estimated to be between 80,000 and 140,000.

False Signup and view all the answers

What principle did automated DNA sequencers primarily operate on?

The method developed by Frederick Sanger Signup and view all the answers

Match the following terms related to DNA cloning with their descriptions:

BAC = Bacterial artificial chromosome YAC = Yeast artificial chromosome polymorphism = Variation in the DNA sequence microsatellite = Repeated sequences of DNA Signup and view all the answers

The largest known human gene is dystrophin, which consists of 2.4 million bases.

True Signup and view all the answers

What is the significance of overlapping regions in DNA sequencing?

They allow for the alignment and assembly of fragmented sequences. Signup and view all the answers

What was one of the main goals of the Human Genome Project?

To address the ethical, legal, and social issues related to the project Signup and view all the answers

The Human Genome Project was completed in 2003.

True Signup and view all the answers

What is the significance of sequencing DNA variations among individuals?

It can lead to new ways to diagnose, treat, and prevent disorders. Signup and view all the answers

The Human Genome Project involved the sequencing of approximately _____ base pairs in human DNA.

3 billion Signup and view all the answers

Match the following organisms with their significance in DNA sequencing:

Bacteria = Model organism for understanding basic cell processes Caenorhabditis elegans = Model organism used in genetic studies Drosophila = Model for studying genetics and development Arabidopsis = Plant model for biological research Signup and view all the answers

Which major organization was NOT mentioned as a contributor to the Human Genome Project?

World Health Organization Signup and view all the answers

The methodologies of the Human Genome Project included only one major approach for sequencing.

False Signup and view all the answers

What are Expressed Sequence Tags (ESTs)?

They are sequences that identify all genes expressed as RNA. Signup and view all the answers

Study Notes

Molecular Basis of Inheritance

Inheritance patterns and their genetic basis were unclear in Mendel's time
DNA (deoxyribonucleic acid) is the genetic material for most organisms
Nucleic acids are polymers of nucleotides
DNA and RNA are two types of nucleic acids found in living systems
DNA is the genetic material in most organisms, while RNA has additional messenger, adapter, structural, and catalytic roles.
Nucleotides structure and linkage to form nucleic acid polymers were discussed in earlier classes.
The structure of DNA (its replication, RNA formation from DNA [transcription], the genetic code for proteins, protein synthesis [translation], and the fundamentals of regulation) is discussed in the chapter.
Determination of the complete human genome sequence in recent years has revolutionized genomics.
The structure of a polynucleotide chain is composed of a nitrogenous base, a pentose sugar (deoxyribose for DNA and ribose for RNA), and a phosphate group.
Nitrogenous bases are either purines (adenine and guanine) or pyrimidines (cytosine, uracil, and thymine).
The information flow from DNA, to RNA to protein synthesis is the basis of the central dogma.
RNA is identified as the first genetic material, evolving to DNA given its greater stability, though RNA can also act as a genetic material for some viruses.
The length of DNA is measured in base pairs (bp), which is about 3x10⁹ bp for the human genome.
The flow of information in some viruses can be reversed, from RNA to DNA.
The complete nucleotide sequence of the human genome has led to a new era of genomics.
The human genome contains 3164.7 million base pairs (bp).
The average gene has roughly 3000 bases.
The total number of genes estimated is around 30,000, though other estimates varied.
Nearly 99.9% of human nucleotides are identical.
More than 50% of genes have unknown functions.
Less than 2% of the genome codes for proteins.
The flow of genetic information in some viruses can be reversed, from RNA to DNA.
There are 3 billion chemical base pairs (bp) in the haploid human genome.
The estimated cost of the human genome project was 9 billion US dollars.
The human genome project took 13 years to complete.

Structure of Polynucleotide Chain

A nucleotide has three components: a nitrogenous base, a pentose sugar, and a phosphate group.
Purines: Adenine and Guanine
Pyrimidines: Cytosine, Uracil, and Thymine
A nucleoside is formed by linking a base to a sugar.
A nucleotide is formed by linking a phosphate group to a nucleoside.
Two nucleotides are joined through a phosphodiester linkage.
The backbone of a polynucleotide chain is composed of sugar and phosphate groups.
Bases are projected from the backbone.

DNA Structure

DNA is a long polymer of deoxyribonucleotides.
DNA has a double helix structure.
The two polynucleotide chains run antiparallel to each other (one strand runs 5' to 3', and the other 3' to 5').
The bases are paired through hydrogen bonding.
Adenine pairs with Thymine, and Guanine pairs with Cytosine.
The double helix has a constant distance between the two strands.
The distance between base pairs in a helix is approximately 0.34 nm.
There are roughly 10 base pairs in each turn.

The Genetic Material is DNA

Hershey and Chase's experiment unequivocally proved that DNA is the genetic material.
DNA was found to be radioactive in the bacteria but not proteins.
The genetic material is stable and can be replicated.
DNA is used more often for storage of genetic information due to its greater stability.

Properties of Genetic Material

DNA acts as genetic material because it has the ability to replicate faithfully and also undergo changes (mutations).
The genetic material must be stable chemically and structurally.
The genetic material should be capable of slow changes (mutations) required for evolution.
DNA is more stable than RNA.

Replication

The central dogma of molecular biology shows the flow of genetic information from DNA to RNA to protein.
DNA replicates semiconservatively (each new strand has one original strand and one newly synthesized strand).
The main enzyme is DNA-dependent DNA polymerase that uses a DNA template to catalyze the polymerization of deoxynucleotides.
Replication is initiated from a specific origin site.

Transcription

Transcription is the process of copying genetic information from one strand of DNA into RNA.
The template strand of DNA provides the information to synthesize RNA.
RNA is a complementary sequence of the template strand, with uracil instead of thymine.
RNA polymerase is the enzyme that catalyzes transcription.
Transcription takes place in the nucleus, where promoter, structural gene and terminator regions on the DNA define the transcription unit.
Transcription is controlled via the presence or absence of an inducer.

The Genetic Code

The genetic code specifies the sequence of amino acids in a polypeptide.
The code is triplet; three bases (a codon) specify a single amino acid.
The genetic code is nearly universal (it applies to most organisms).
Some amino acids are coded by more than one codon (the genetic code is degenerate).
AUG codon codes for methionine and also acts as the initiator codon.
There are stop codons (that do not code for amino acids, that signal termination of the protein synthesis).

Mutation

Mutations lead to changes in the reading frame of the gene sequence.
Mutations can result in various consequences, such as changes from the original amino acid sequence or loss of the amino acid
Frame-shift mutations result from insertions or deletions of one or two bases, altering the entire downstream sequence.

tRNA- The Adapter Molecule

tRNA molecules are required to bring amino acids to the site of translation.
tRNA has an anticodon loop that recognizes the specific codon on mRNA.
tRNA molecules carry the appropriate amino acid corresponding to a specific mRNA codon.

Translation

Translation is when mRNA sequence is used to synthesize proteins.
The ribosome is the organelle responsible for translation.
The process of translation occurs in initiation, elongation, and termination phases.
The sequence of amino acids is determined by the mRNA sequence of codons.

Regulation of Gene Expression

Gene expression is regulated at multiple levels to control the synthesis rate of proteins.
Bacteria use operons, which are groups of genes that are regulated together, to regulate transcription.
Eukaryotic regulation occurs at several levels, including transcription, RNA processing, and RNA stability.
Translation is also regulated in cells.
One example of a controlled gene expression mechanism is the lac operon.

The Lac Operon

The lac operon is a system in E. coli that controls the expression of genes needed to use lactose as an energy source.
The lac operon is inducible and contains three critical genes, allowing for the production of enzymes relevant to lactose utilization when present in the environment.
The operon is repressed when lactose is not available.
The lac operon is described more extensively in this chapter, including the mechanisms and regulation via the inducer.

Human Genome Project

The human genome project aimed to determine the DNA sequence of the human genome.
Key goals of HGP include identification of all human genes, determination of the base pair sequence of the entire human genome, and creation of databases.
The complete sequence of a human genome was finished in 2003.
The project led to revolutionary new insights into genetic diversity, gene function, disease associations, and evolutionary relationships.

DNA Fingerprinting

The main basis for DNA fingerprinting is the presence of repetitive DNA sequences, including Variable Number Tandem Repeats (VNTRs).
DNA fingerprinting is used for identification of individuals and in forensic science applications.
In DNA fingerprinting, the various differences in the repetitive sequences in the genes among individuals are used to differentiate between them.
Several techniques are used to perform DNA fingerprinting, including Southern blotting and PCR amplification.
The use of DNA fingerprinting has had an impact across numerous scientific and forensic disciplines.

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Test your knowledge on nucleotides, their structure, and the genetic code in this comprehensive quiz. Topics include the base pairs of bacteriophage lambda, types of nitrogenous bases, and the significance of codons in protein synthesis. Challenge yourself with questions about DNA and RNA, their components, and key historical figures in genetics.

NCERT - MOLECULAR BASIS OF INHERITANCE - 24-25

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Questions and Answers

What is the total number of base pairs in bacteriophage lambda?

Uracil is found in DNA.

Name the two types of nitrogenous bases found in nucleotides.

A nucleotide consists of a nitrogenous base, a pentose sugar, and a __________.

Match the nitrogenous bases with their categories:

Which of the following links nucleotides together to form a polynucleotide chain?

Friedrich Meischer was the first to isolate DNA in its native form.

What additional group is present in RNA that is not found in DNA nucleotides?

What was George Gamow's proposition about the genetic code?

The codon is read in RNA with punctuation marks.

Which three codons do not code for amino acids?

The amino acid coded for by the codon AUG is __________.

What does the genetic code being 'degenerate' imply?

The enzymes developed by Har Gobind Khorana were used in __________ synthesis of RNA.

What is the relationship between amino acids and mutations in genetic code studies?

Match the following codons to their corresponding amino acids:

What is the function of the anticodon loop in tRNA?

Initiator tRNA is specific only to start codons, which signals the beginning of translation.

What is the role of ATP in the process of tRNA charging?

The ribosome is composed of structural RNAs and approximately _____ different proteins.

Match the following components with their functions in translation:

What is the structural form of tRNA in its actual state?

There are specific tRNAs for stop codons during the translation process.

What is the purpose of the peptide bond?

What is the primary purpose of cloning DNA fragments in sequencing?

Sanger's method is solely used for determining DNA sequences.

What is the total estimated number of genes in the human genome?

The largest known human gene is __________, consisting of 2.4 million bases.

What percentage of base sequences among humans are the same?

Match the following terms with their descriptions:

Chromosome 1 has the fewest number of genes among human chromosomes.

Which of the following is NOT a feature of the human genome project?

What are single nucleotide polymorphisms (SNPs)?

DNA fingerprinting is a quick way to compare DNA sequences of ______ individuals.

Over 50% of discovered genes have unknown functions.

In what year was the sequencing of chromosome 1 completed?

Match the following chromosomes with the correct number of genes:

What role do repetitive sequences play in the human genome?

The human genome is estimated to consist of 3 billion base pairs.

What is one major application of DNA sequencing mentioned?

What does VNTR stand for in the context of DNA fingerprinting?

DNA fingerprinting was developed by Francis Crick.

What is the primary role of polymorphisms in evolution?

The technique of DNA fingerprinting includes __________ as a step that involves identifying the DNA fragments.

Match the following steps of DNA fingerprinting with their descriptions:

What is the maximum size of VNTR fragments that can be obtained?

Identical twins have the same VNTR patterns.

What technique enhances the sensitivity of DNA fingerprinting?

What is the sugar component of DNA nucleotides?

Cytosine is found in both DNA and RNA.

What type of linkage connects nucleotides in a polynucleotide chain?

A __________ is formed when a nitrogenous base is linked to a pentose sugar.

Match each nitrogenous base with its category:

What is the function of the 5' end of a polynucleotide chain?

Uracil replaces Thymine in RNA.

Who first identified DNA as 'Nuclein'?

What type of DNA replication was proposed by Watson and Crick?

RNA is more stable than DNA.

Who were the scientists that provided experimental proof for semiconservative DNA replication?

DNA's double-stranded structure allows for a process of ________ to repair changes.

What allows DNA to resist changes over time?

Match the following scientists with their contributions to DNA research:

Each DNA molecule after replication will have two newly synthesized strands.

What biochemical issue did RNA face that led to the evolution of DNA?

What process describes the flow of genetic information in most organisms?

The distance between two consecutive base pairs in DNA is approximately 0.34 nm.

What is the name of the structure formed when DNA is packaged with histones in eukaryotic cells?

In some viruses, the flow of information is from RNA to __________.

Match the following structures with their descriptions:

How long is the DNA double helix in a typical mammalian cell?

Histones are negatively charged proteins that assist in DNA packaging.

Which two amino acids are histones rich in that contribute to their positive charge?

What defines the 5' end of a transcription unit?

Eukaryotic genes are typically polycistronic.

What term describes the sequences that do not appear in mature RNA?

The DNA sequence coding for tRNA or rRNA also defines a ______.