Biology Chapter on DNA and Genetics

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What substance was identified as the 'transforming agent' responsible for the inheritable change in bacteria?

Proteins

Carbohydrates

Lipids

DNA (correct)

What significant discovery was made by Frederick Griffith in 1928 regarding bacteria?

All bacteria can become pathogenic without interaction.

Dead pathogenic cells can transform non-pathogenic bacteria. (correct)

Proteins serve as the genetic material in bacteria.

Live cells are more dangerous than dead cells.

Who were the scientists credited with discovering the double helix structure of DNA in 1953?

Rosalind Franklin and Maurice Wilkins

Alfred Hershey and Martha Chase

Frederick Griffith and Oswald Avery

James Watson and Francis Crick (correct)

What was the main contribution of Hershey and Chase's experiment in 1952?

Showing that nucleic acids constitute the genetic material in viruses. Signup and view all the answers

What are nucleotides considered to be in the context of nucleic acids?

The building blocks of nucleic acids. Signup and view all the answers

What role does the enzyme topoisomerase play during DNA replication?

It unwinds the DNA strand. Signup and view all the answers

What happens to the chromatin fibre before mitosis or meiosis?

It is duplicated identically. Signup and view all the answers

Which process involves base pairing as a fundamental principle?

DNA transcription. Signup and view all the answers

How much of the human genome is coding DNA?

About 2%. Signup and view all the answers

What structure is formed when the chromatin fibre coils around histones?

Chromatin fibre. Signup and view all the answers

What is the primary function of RNA being single-stranded?

To allow for specific functional roles. Signup and view all the answers

What is the average gene length in terms of base pairs in the human genome?

3,000 base pairs. Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

S phase. Signup and view all the answers

How many total codons can be formed from the four nucleotide bases?

64 Signup and view all the answers

Which of the following codons serves as a start signal for protein synthesis?

AUG Signup and view all the answers

Which statement correctly describes the genetic code?

It is universal across all organisms. Signup and view all the answers

What is the role of tRNA in the process of translation?

To transport amino acids to the ribosome. Signup and view all the answers

What are the three codons that signal the end of protein synthesis?

UGA, UAA, UAG Signup and view all the answers

How many types of tRNA correspond to the codons available for amino acids?

61 Signup and view all the answers

What is the function of the anticodon in tRNA?

To match complementary codons on mRNA. Signup and view all the answers

What is a feature of the genetic code described as 'degenerative'?

Most amino acids have more than one corresponding codon. Signup and view all the answers

Which antibiotic is known for its use against tuberculosis and leprosy?

Rifampicin Signup and view all the answers

What is the primary mechanism of action for α-Amanitin in eukaryotic cells?

Inhibition of RNA polymerase II Signup and view all the answers

What is the function of the A-site in the ribosome?

It is where the first amino acid, methionine, binds to the tRNA. Signup and view all the answers

Which of the following antibiotics causes a conformational change in the ribosome of prokaryotes?

Streptomycin Signup and view all the answers

What happens when a stop codon appears during translation?

The growing amino acid chain is released from the ribosome. Signup and view all the answers

Which antibiotic primarily binds to prokaryotic ribosomes and causes peptide chain termination?

Puromycin Signup and view all the answers

Which of the following is true about aminoacyl tRNA synthetases?

They load tRNAs with the appropriate amino acid. Signup and view all the answers

Which antibiotic is classified as a broad-spectrum antibiotic?

Tetracycline Signup and view all the answers

What effect does streptomycin have on prokaryotic ribosomes?

Alteration of the ribosomal structure Signup and view all the answers

What role does GTP play in translation?

It is used for the migration of the ribosome along the mRNA. Signup and view all the answers

What is the consequence of an error during the binding of tRNA with an amino acid?

The incorrect amino acid will be incorporated into the growing chain. Signup and view all the answers

Which compound is derived from the green death cap mushroom and inhibits transcription?

α-Amanitin Signup and view all the answers

Which of the following antibiotics specifically targets the 50S ribosomal subunit in prokaryotic cells?

Puromycin Signup and view all the answers

Which antibiotic inhibits bacterial protein synthesis by binding to the 50S subunit of ribosomes?

Chloramphenicol Signup and view all the answers

What ultimately happens to mRNA after sufficient protein is synthesized?

It is broken down. Signup and view all the answers

What is the consequence of having no tRNA for a stop codon?

The amino acid chain is released, terminating translation. Signup and view all the answers

What happens to the genes for lactose breakdown when E.coli is placed in a medium containing lactose?

They are induced. Signup and view all the answers

What is the primary purpose of end-product repression in E.coli?

To conserve energy. Signup and view all the answers

How do anabolic metabolic reactions like tryptophan production get regulated?

The genes are repressed when enough of the product is formed. Signup and view all the answers

What is the significance of the timing it takes for E.coli to switch from glucose to lactose nutrition?

It shows the preference for glucose as the nutrient. Signup and view all the answers

How many different mRNA molecules are produced for lactose-degrading enzymes, and how many enzymes arise from this?

Multiple mRNAs and multiple enzymes. Signup and view all the answers

What type of genes are constitutive genes?

Genes that are always expressed. Signup and view all the answers

Where do RNA polymerase and the repressor bind on the lac operon?

At the operator and promoter regions. Signup and view all the answers

How is the repressor of the lac operon deactivated?

By binding of lactose or an analog. Signup and view all the answers

Study Notes

Molecular Biology Terminology

DNA strand: A single strand of DNA
Molecule: A group of atoms bonded together
Pathogenic, Pathogenous: Causing disease
Chemical substance: A material with a definite composition
Transform (transformed, transformed): To change the nature or form of something
Culture medium: A liquid or gel that supports the growth of cells or microorganisms (plural: media)
Protein synthesis: The process of creating proteins
Nucleic acid: A molecule, either DNA or RNA, that carries genetic info
Double helix: A twisted ladder shape of DNA
Nucleotide: A monomer of nucleic acids, made of a sugar, a phosphate, and a base
Base pairing: Specific pairing of nitrogen bases (A with T, G with C)
Pyrimidine: A nitrogen-containing base in DNA and RNA (Cytosine, Thymine, Uracil)
Purine: A nitrogen-containing base in DNA and RNA (Adenine, Guanine)
Adenine: A nitrogenous base, found in DNA and RNA
Guanine: A nitrogenous base, found in DNA and RNA
Cytosine: A nitrogenous base, found in DNA and RNA
Thymine: A nitrogenous base, found only in DNA
Uracil: A nitrogenous base, found only in RNA
Pentose: A 5-carbon sugar
Ribose: A 5-carbon sugar (in RNA)
Deoxyribose: A 5-carbon sugar (in DNA)
Phosphoric acid: A chemical compound containing phosphorus
Nucleoside: A nucleotide without the phosphate group
Adenosine triphosphate (ATP): A high-energy molecule
Deoxycytidine: A nucleoside found in DNA
Coenzyme: A non-protein compound necessary for the function of some enzymes
Phosphodiester bond: A chemical bond
3'-end / 5'-end (“3′ / 5′ prime end"): The end of a strand of nucleic acid
Genetic information: Information passed from one generation to the next
RNA: Ribonucleic Acid

Other Molecular Biology Terms

Gel electrophoresis: A technique to separate charged molecules in an electric field
Single-stranded: Having only one strand, unlike double-stranded DNA
Replication fork: The point where DNA strands separate during replication
Helicase: An enzyme that unzips the DNA double helix
Single strand binding proteins: Prevent DNA strands from re-annealing
DNA polymerase (I, III): Enzymes that synthesize DNA strands during replication
Ligase: An enzyme that joins DNA fragments together
Leading strand: The strand synthesized continuously during DNA replication
Lagging strand: The strand synthesized discontinuously during DNA replication
Okazaki fragments: Short segments of DNA synthesized discontinuously on the lagging strand
Primer: A short, single-stranded DNA or RNA molecule essential for initiating DNA replication
Primase: Enzyme that builds primers
Telomeres: Protective caps at the ends of chromosomes
Gen, genes: A gene is a segment of DNA that codes for a protein or a functional RNA. Genes contain the instructions for making proteins (and some functional RNA).
Molecular life / biological clock: Molecular mechanisms controlling cell cycles and potentially life spans
Germ-line cells: Cells that give rise to gametes (eggs or sperm)
Telomerase: Enzyme that maintains telomere length
Amino acid: Building blocks of proteins
Protein chain: A chain of amino acids
Mutation: A permanent change in the DNA sequence
Proofreading: The process of removing errors in DNA replication
Polymerase chain reaction (PCR): Technique for amplifying DNA
Amplification: Increasing the number of copies of a DNA sequence
Denaturation: The process in which the DNA is separated into two strands
Annealing, hybridisation: Binding of DNA segments with complementary sequences
Polymerization / elongation/ extending: Adding new bases to a growing DNA chain
Enzyme:Biological catalyst
Metabolism: The chemical processes of maintaining life
Messenger RNA (mRNA): RNA that carries the message from the DNA to the cytoplasm
Transfer RNA (tRNA): Small RNA molecules that transport amino acids during protein synthesis
Ribosomal RNA (rRNA): RNA that is part of the structure of ribosomes
small nuclear RNA (snRNA):involved in RNA processing
small interfering RNA (siRNA):involved in silencing gene expression
Copy: Replicating genetic material
Ribosome:The site for protein synthesis in cells. Composed of RNA and proteins
Amino acid chain: A chain of amino acids built in a specific order to make up proteins
Clover-leaf: A simplified diagram of tRNA shape
Spliceosome: RNA-protein complex that splices RNA
RNA interference: Mechanism of gene silencing using short RNA molecules to target mRNA
To silence (silenced, silenced): To reduce or stop the activity of a genetic material
Promoter: A specific region in DNA that signals the start of transcription
Terminator: A specific region in DNA that signals the end of transcription
Initiation: Beginning of DNA replication/transcription/translation
Elongation: During replication, the addition of nucleotides to the growing DNA chain
Termination: End of replication/transcription/translation
Complementary strand: A strand of RNA or DNA that has a sequence that is complementary to that of another strand

Additional Terms

Genome mutation: Changes affecting whole sets of genes
Chromosome mutation: Changes in chromosome structure
Gene mutation: Changes in single genes
Point mutation: A change in only one nucleotide pair
Substitution: Replacing one nucleotide with another
Silent mutation: No change to the amino acid coded for by a mutated codon
Missense mutation: A change in a nucleotide that changes the amino acid that is coded for
Nonsense mutation: A change in a nucleotide that creates a premature stop codon
Frame-shift mutation: A change that shifts the reading frame, causing a significant change in the amino acid sequence from the change point onwards
DNA damages: Damage to the DNA
Lung cells: Cells in the lungs
UV light: Ultraviolet light
X-ray radiation: Electromagnetic radiation
Cigarette: Contains many toxins such as nicotine which can damage DNA
Skin cell: Cells in the skin
Repair enzymes: Enzymes that fix DNA damage
Yeast: Unicellular fungus
Dimers: Chemical bonds formed when two nucleotide bases are linked together
Spontaneous mutation: A mutation that arises without any known cause
Deamination: Chemical modification of a nucleotide
Mutagens: Agents that cause mutations
Cross-linking: Chemical bonds forming between different parts of the DNA
Stretching of the DNA: An actual physical twisting or stressing of the DNA chain
Intercalating substances: Molecules that intercalate into the DNA helix, causing problems during replication
Antibiotics: Drugs that kill bacteria
Cytostatics: Cancer drugs
Excision repair: A DNA repair process involving the removal and replacement of damaged DNA segments
Base analogues: Molecules that are structurally similar to DNA bases but have different base-pairing properties
Single strand breaks: Breaks in one strand of the DNA
Loss of end piece: Deletion of a section at the end of the chromosome
Deletion: Removing a segment of DNA
Insertion: Adding a segment of DNA
Shift in the reading frame: A change that alters the three-nucleotide groups read during translation
Reading-frame shift: see "shift in the reading frame"
Compartmentalisation: Segregation of cellular compartments
Gene expression: The process of converting genetic information into functional proteins
Destructive / catabolic processes: Break-down reactions
Constructive / anabolic processes: Build-up reactions
Operon: A group of genes that are regulated together
Substrate induction: When enzyme synthesis is triggered based on the presence of the substrate
End product repression: When enzyme synthesis is reduced or stopped based on the high concentration of product
Repressor: A protein that binds to the operator and prevents transcription
Binding site: Specific locations for binding of other molecules or proteins
Induction: The switch or process to turn a gene on or off
Structural genes: Genes that code for proteins
Constitutive genes: Genes that are expressed continuously
Lac operon: A group of genes involved in lactose metabolism
Tryptophan
Gene / genetic technology / genetic engineering: Molecular techniques involved in manipulation to improve or alter an organism/gene
Gene therapy: Correction of diseased genes using genetic techniques
Isolation: The separation of a particular molecule from a mixture

DNA Replication and Transcription

DNA replication: The process of replicating DNA
Template: The pattern for creating another strand of DNA or RNA
Topoisomerase: Enzymes that ease DNA strain during replication
Helicase: Enzyme that unwinds the DNA double helix
SSB proteins: SIngle-strand binding proteins, prevent DNA from reforming a double helix
DNA Polymerase III: Enzyme that synthesizes DNA
DNA Polymerase I: Enzyme that removes primers and fills gaps in the lagging strand during DNA replication
Primase: Make the RNA primers that begin the strand building at the start of each replicating segment
Okazaki fragments: Short segments of DNA synthesized discontinuously on the lagging strand during replication
RNA primers: Short RNA sequences required for DNA polymerase to initiate new strand synthesis
DNA ligase: Links the RNA primers and Okazaki fragments together
Transcription: Converting DNA instructions into mRNA which then codes for proteins
RNA polymerase: Enzyme that carries out transcription
Promoter: The starting point of gene transcription
Terminator: The ending point of transcription

Transcription in Prokaryotes and Eukaryotes

mRNA: Messenger RNA is RNA that codes for protein synthesis and is transcribed from DNA
Codogenic/template strand/matrix strand/antisense strand: The strand of DNA used as a template to synthesize mRNA, the complementary strand is non-coding and is also known as the antisense strand
Introns: Non-coding regions that are spliced out of mRNA
Exons: Coding regions that are part of the final mRNA
Splicing: The process of removing introns and joining exons during RNA processing
3' & 5' end: The ends of a transcribed sequence.
RNA polymerase: The enzyme that carries out transcription of DNA to produce mRNA

Gene Regulation

Operon: A group of genes that are regulated together
Substrate induction: When enzymatic synthesis is triggered based on the presence of the substrate
End product repression: When enzymatic synthesis is reduced or stopped based on the high concentration of product
Repressor: A protein that binds to the operator and prevents transcription from occurring
Binding site: The specific location of binding for a protein and a gene

General Terms

Genetic code: The set of rules by which information encoded in genetic material is translated into proteins
Universal: The same genetic code is used by all living organisms
Codons: Groups of three nucleotides in the mRNA that code for an amino acid
Degenerate: When multiple codons code for the same amino acid in the genetic code
Amino acids: Building blocks of proteins.
Translation: The synthesis of proteins from an mRNA template
Ribosomes: The organelle in cells where translation occurs.
tRNA: Transfer RNA delivers amino acids to the ribosome during translation
Anticodon: Part of the tRNA molecule that pairs with the mRNA codon
Antibiotics: Medications that kill or inhibit the growth of living microbes; bacteria, fungi, protists or viruses. These substances are not always universally effective across different species (or strains)

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on DNA, genetics, and the significant discoveries that shaped our understanding of heredity. This quiz covers key experiments, structures, and processes related to nucleic acids and their functions. Perfect for students looking to review critical biology concepts.