Biology Chapter: DNA and Genetics

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Questions and Answers

What is the role of DNA in transcription?

It is duplicated to form chromosomes.

It is coiled around histones.

It serves as a template for RNA synthesis. (correct)

It gets translated into proteins.

What happens to the chromatin fiber before mitosis?

It coils further around histones.

It is duplicated identically. (correct)

It becomes less condensed.

It undergoes transcription.

Which enzyme is responsible for unwinding the DNA strand during replication?

Helicase

DNA polymerase

Topoisomerase (correct)

Ligase

What did Frederick Griffith demonstrate about bacteria in 1928?

Harmless bacteria can become pathogenic. Signup and view all the answers

In the context of DNA structure, what is a metaphase chromosome characterized by?

Being maximally shortened and thickened. Signup and view all the answers

What is the approximate length of a human gene?

3,000 base pairs Signup and view all the answers

Which substance was identified as the 'transforming agent' by Oswald T. Avery in 1944?

DNA Signup and view all the answers

What did Hershey and Chase conclude in 1952 regarding genetic material?

Nucleic acids are the genetic material in viruses. Signup and view all the answers

What percentage of the human genome is coding?

2% Signup and view all the answers

How many genes are estimated to be present in the human genome?

30,000 to 35,000 Signup and view all the answers

What is a key structural feature of DNA that was discovered by Watson and Crick in 1953?

It consists of two strands forming a double helix. Signup and view all the answers

What structural component does DNA coil around to form chromatin?

Histones Signup and view all the answers

What are nucleotides considered in the context of nucleic acids?

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

Which of the following bases is found in RNA but not in DNA?

Uracil Signup and view all the answers

What sugar is present in RNA nucleotides?

Ribose Signup and view all the answers

What is the chemical structure of phosphoric acid?

H3PO4 Signup and view all the answers

Which type of nucleotide is ATP derived from?

Adenosine monophosphate Signup and view all the answers

Which of the following pairs correctly identifies a purine base?

Adenine and Guanine Signup and view all the answers

What is the role of phosphoric acid in nucleotide structure?

Links nucleotides through ester bonds Signup and view all the answers

At which carbon positions do phosphoric acid esterify with pentose in nucleotide chains?

C3' and C5' Signup and view all the answers

Which of the following statements about nucleotides is incorrect?

All bases are purines. Signup and view all the answers

What is the main consequence of damage to both strands of DNA?

Frameshifts leading to dysfunctional proteins Signup and view all the answers

What distinguishes the concept of a gene in prokaryotes from that in eukaryotes?

Eukaryotic genes contain introns interrupting the coding sequence. Signup and view all the answers

How does alternative splicing contribute to protein diversity in humans?

It generates several proteins from a single gene by varying exon inclusion. Signup and view all the answers

What happens to single strand breaks in DNA?

They can be repaired using the complementary strand as a template. Signup and view all the answers

What is the purpose of the control of gene activity in bacterial cells?

To express only the necessary genes at a given time. Signup and view all the answers

What is the outcome of frameshift mutations on protein function?

They generally result in non-functional proteins. Signup and view all the answers

What is exon shuffling capable of generating?

Diverse proteins from a few genes. Signup and view all the answers

Which statement about gene counting in humans is accurate?

Humans have approximately 30,000 genes that code for numerous proteins. Signup and view all the answers

What is the primary mechanism of action for Rifampicin?

Inhibits DNA-dependent RNA polymerase Signup and view all the answers

Which antibiotic causes conformational changes that lead to reading errors in prokaryotes?

Streptomycin Signup and view all the answers

What is the effect of Tetracycline on prokaryotic ribosomes?

Binds to the 30S ribosomal subunit Signup and view all the answers

Which of the following antibiotics is used experimentally and causes termination of peptide chains?

Puromycin Signup and view all the answers

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

Inhibits mRNA synthesis by binding to RNA polymerase II Signup and view all the answers

Which of the following statements about Streptomycin is accurate?

It causes errors in protein translation due to conformational changes. Signup and view all the answers

Which type of drug is α-Amanitin classified as?

Cytostatic agent Signup and view all the answers

What type of infections is Rifampicin primarily used to treat?

Bacterial infections such as tuberculosis and leprosy Signup and view all the answers

How are foreign genes introduced into bacteria?

Through natural transformation using plasmids. Signup and view all the answers

What methods are used to integrate foreign genes into plant and animal cells?

Gene guns and microinjection. Signup and view all the answers

Which of the following are examples of genetically modified organisms?

Bt corn, Golden rice, and Dolly the sheep. Signup and view all the answers

What are the current aims of gene therapy in humans?

To cure genetic disorders by correcting defective genes. Signup and view all the answers

What are foundational experiments that contributed to molecular biology?

Experiments by Griffith, Avery, Hershey & Chase, and the discovery by Watson & Crick. Signup and view all the answers

Which components are essential for understanding the structure of DNA?

Nucleotides, sugars, and phosphate groups. Signup and view all the answers

How do prokaryotes differ in their transcription process compared to eukaryotes?

Transcription occurs in the cytoplasm and does not require pre-mRNA processing. Signup and view all the answers

Which of the following describe the role of RNA in cells?

RNA serves as a template for protein synthesis and gene regulation. Signup and view all the answers

Study Notes

Molecular Biology Terminology

DNA strand: A single strand of DNA molecules
Molecule: A group of atoms bonded together.
Pathogenic, Pathogenous: Causing disease
Chemical substance: Matter with a specific chemical composition
Transform (transformed, transforming): To change or convert into another form
Culture medium (plural: media): A liquid or gel used to grow cells
Protein synthesis: The production of proteins from amino acids according to DNA instructions
Nucleic acid: A molecule that contains genetic instructions
Double helix: A twisted ladder structure of DNA
Nucleotide: The building block of nucleic acid, consisting of a sugar molecule, a phosphate molecule, and a nitrogenous base
Base pairing: The specific pairing of nitrogenous bases in DNA (A with T, and G with C)
Pyrimidine: A nitrogenous base (cytosine, thymine, or uracil)
Purine: A nitrogenous base (adenine or guanine)
Adenine: A purine nitrogenous base
Guanine: A purine nitrogenous base
Cytosine: A pyrimidine nitrogenous base
Thymine: A pyrimidine nitrogenous base
Uracil: A pyrimidine nitrogenous base

Molecules of Nucleic Acids

Pentose: A five-carbon sugar molecule
Ribose: A type of pentose sugar found in RNA
Deoxyribose: A type of pentose sugar found in DNA
Phosphoric acid: A molecule essential for forming the backbone of nucleic acids
Nucleoside: A molecule consisting of a nitrogenous base and a pentose sugar
Adenosine triphosphate (ATP): A molecule that provides energy for various cellular processes
Deoxycytidine: A nucleoside
Coenzyme: A non-protein organic molecule that facilitates enzyme function
Phosphodiester bond: A chemical bond used for linking nucleotides in a polynucleotide chain
3'-end/5'-end ("3/5 prime end"): The end points of a DNA or RNA strand
RNA, Ribonucleic acid: A nucleic acid that plays a role in protein synthesis and other functions
Deoxyribonucleic acid (DNA): A nucleic acid that contains the genetic instructions
Hydrogen bonds/bridges: Weak bonds that hold the two strands of DNA together
rope ladder: An analogy for DNA or RNA structure
coding = template /matrix / antisense strand A strand of DNA or RNA that acts as a template for RNA synthesis or protein synthesis
replication: The process by which DNA creates copies of itself
transcription: The process of copying genetic information from DNA to RNA

DNA Replication and Repair

Gel electrophoresis: A technique used to separate DNA fragments
Single-strand: A DNA or RNA molecule having only one strand
Replication fork: A site of replication where the DNA double helix is separated into two strands
Helicase: An enzyme that unwinds the DNA double helix
Single strand binding proteins: Proteins that prevent the two separated DNA strands from rejoining
DNA polymerase I/III: Enzymes involved in DNA replication
Ligase: Enzyme that joins DNA fragments
Leading strand: The strand replicated continuously during DNA replication
Lagging strand: The strand replicated discontinuously during DNA replication
Okazaki fragments: Short fragments of DNA produced during lagging strand replication
Primer: A short nucleic acid sequence that serves as a starting point for DNA synthesis
Primase: An enzyme that synthesises RNA primers
Telomeres: Repeated nucleotide sequences at the ends of chromosomes
Gen/Genes: A segment of DNA that codes for a protein
Molecular life/biological clock / germ-line cells: Concepts of life history
Telomerase: Enzyme that maintains telomere length in germline cells
Amino acid: The building block of proteins
Protein chain: A long chain of amino acids
Mutation: A change in the DNA sequence
Proofreading: A process that corrects errors during DNA replication
Polymerase chain reaction (PCR): A method used to amplify DNA sequences in vitro
Amplification: Increasing the amount of a substance in a test sample

Other Biological Concepts

Denaturation: The process of separating double-stranded DNA into single strands
Annealing, hybridisation: Binding of complementary strands of DNA or RNA
Polymerisation/elongation/extending: The process of adding components to a growing polymer
Enzyme: A biological catalyst
Metabolism: All chemical processes in a cell
Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes for protein synthesis
Transfer RNA (tRNA): Carries amino acids to the ribosomes
Ribosomal RNA (rRNA): Forms part of the ribosome structure
Small nuclear RNA (snRNA): A type of RNA involved in RNA splicing
Small interfering RNA (siRNA): A type of RNA involved in gene silencing
Copy/ribosome: Processing steps
Amino acid chain: The order of amino acids in a polypeptide or protein.
Clover leaf: A depiction of common tRNA structure.
Spliceosome: A complex that edits RNA
RNA interference: A process for regulating gene expression.
To silence (silenced, silenced): To stop or decrease the activity of a gene
Promoter: Segment of DNA at the start of a gene, crucial for transcription
Terminator: Segment of DNA at the end of a gene, crucial for transcription
Initiation: The start of a process, including the initiation of transcription and translation.
Elongation: The middle of a process, including elongation during transcription and translation
Termination: The end of a process, including the termination of transcription and translation
Complementary strand: A strand of DNA or RNA that precisely matches another strand in its base sequence but runs in the opposite direction.
Backbone: A structural element of DNA or RNA consisting of alternating sugar and phosphate molecules.

Genome Mutations and Damage

Genome mutation/chromosome mutation: alterations involving the overall genome or an individual chromosome
Gene mutation: alterations affecting a specific gene
Point mutation: alteration involving just one nucleotide pair
Substitution: replacement of one nucleotide with another
Silent mutation: change in a nucleotide that does not change the coded amino acid
Missense mutation: alteration in the DNA that produces a different amino acid in the resulting protein.
Nonsense mutation: alteration that creates a stop codon
Frame-shift mutation: causes the reading frame of the gene to shift, often resulting in an entirely different protein sequence
DNA damages: Chemical or structural changes in the DNA molecules.
Lung cells/UV light/X-ray radiation/cigarette/skin cell: Examples of where damage can occur
Repair enzymes/yeast/dimers: Examples of the mechanisms for fixing damage
Spontaneous mutation: A change in the DNA sequence created by errors during DNA replication or by exposure to DNA-damaging events.
Deamination: A chemical change in DNA bases that can lead to mutations
Mutagens: Substances that cause mutations
Cross-linking: A covalent link between two macromolecules or different parts of the same macromolecule

Intercalating Substances

Antibiotics Drugs that work against bacteria & infections
Cytostatics/excision repair/base analogues: Treatments for cancer/processes for fixing damaged DNA damage
Single strand breaks: Interrupted single strands of DNA

Gene Expression

Deletion: Loss of one or more segments of genetic material
Insertion: Addition of one or more segments of genetic material
Shift in the reading frame/reading-frame shift: Frameshift caused by insertions or deletions altering following amino acid sequence
Compartmentalization: organization of a cell or structure into separate and distinct compartments
Gene expression: Process of using a gene's information to create a protein.
Destructive/catabolic processes: Chemical reactions for breaking down molecules
Constructive/anabolic processes: Chemical reactions for building up molecules
Operon: group of genes that function together
Substrate induction: activation of an operon in response to an environmental stimulus
End product repression: shutting off the creation of a product if it reaches a certain concentration in the environment
Repressor: protein that can bind to a section of DNA to either block or activate an operon
Binding site: The place where a repressor will bind
Induction: Activation of the expression of a gene
Structural genes: genes coding for proteins
Constitutive genes: genes that are always expressed

Regulated Genes

Lactose (milk sugar): A sugar
Regulator gene: controls the expression of other genes
Tryptophan An essential amino acid
Gene/genetic technology/genetic engineering Alteration or study of genes
Gene therapy: treatment of diseases using gene alterations
Isolation: Separation of genetic material in an experiment
Recombination: rearrangement of genetic material
Gene transfer: Introduction of foreign genes into an organism
Selection: Choosing specific genetic changes/materials from a population
Cell reproduction/cell propagation: Multiplication of cells
Restriction enzymes: Enzymes recognizing and cleaving specific DNA sequences
Recognition sequence/site: Specific DNA sequences where a restriction enzyme cuts
Palindrome(/inverted repeat): DNA sequences that read the same backward and forward
Sticky ends/blunt ends: Specific ends of DNA fragments that result from restriction enzyme processing
Ori (= origin of replication): The starting point of DNA Replication
Recombinant plasmid/vector: Materials that can be used for gene transfer
Marker genes/GFP (= green fluorescent protein): Identifying characteristics in a experiment
Microinjection: A technique for introducing DNA into cells

Molecular Biology Historical Experiments & Concepts

Agrobacterium/calcium phosphate precipitation/lipid infection/electroporation/particle gun/genomic library/hybridisation probe/insulin Techniques in molecular biology experimental design
Genetic fingerprint/microsatellites(=Short Tandem Repeats)/transgenic/gene-modified/gene pharming/green gene technology/Bt maize (Bt = Bacillus thuringiensis)/Amflora potato/antisense foreign gene: Gene altering technology applications in genetic engineering

Nucleic Acid Structure

Phosphoric acid (Exact formula): Chemical formula for phosphoric acid
Difference between ribose and deoxyribose: Details on the chemical structure difference that distinguishes them
Purine, pyrimidine bases identification of base structures

Glossary of DNA and RNA Structures

DNase: An enzyme that degrades DNA
3'-end (5'-end): The end points of a DNA or RNA strand
Phosphodiester bond: A link between phosphate and sugar that forms the backbone of DNA/RNA chains

Linking Nucleotides

Phosphoric acid: Forms phosphodiester bonds, linking nucleotides.
3' and 5' carbons of the sugar: Involved in phosphodiester bonds.

DNA and RNA Differences

Pentose sugar: The different types of pentose sugars
Bases: The different types of bases in DNA and RNA
Number of strands: The number of strands (single or double) present in each molecule

Chromosomes

Gen-length/promoter-length/transcription duration/genome of human: Key information on chromosomal characteristics
During early interphase, each chromosome consists only of one chromatid.

DNA Replication

Topoisomerase/helicase/single-strand binding proteins/DNA polymerase III: Various enzymes involved in DNA replication
Leading strand/lagging strand/Okazaki fragments/primer/primase: Details about the replication processes
DNA replication speed(fruit fly): Rates - Replication is a quick process compared to other cellular operations

DNA Replication Inhibitors

Antibiotics/Gyrase inhibitors/Zytostatika: Examples of DNA inhibitors

Polymerase Chain Reaction

PCR (polymerase chain reaction)-in vitro DNA replication: How PCR functions to replicate DNA outside a cell

Function of Different RNA Types

mRNA/tRNA/rRNA/snRNA/siRNA: Roles, types, and functions of RNA molecules

Transcription in Prokaryotes

Coding/template strand/matrix strand/antisense strand/mRNA synthesis: Information flow processes in prokaryotic cells
mRNA length/start and stop sequence for RNA polymerase/non-coding regions in eukaryotic DNA/end of eukaryotic mRNA: Specific aspects of transcription in prokaryotes
Replikation/Transkription Comparison Table: Side-by-side comparison of the processes

Genetic Code

Base codons/Aminosäuren/Codons/genetic code: Details on the triplet code & the connection with amino acids

Translation

Template (mRNA)/interpreter (tRNA)/dictionary (genetic code)/place where the process takes place (ribosomes): Key actors in the translation process.

Transcription and Translation Inhibitors/Drugs

Chloramphenicol/Erythromycin/Fusidic Acid/Rifampicin: Details about the mechanism of action of the drugs against transcription/translation

Mutations

Changes to the DNA/DNA damage/repair enzymes: Overview of damaging events to the molecular structure of DNA.
Genome mutations/Chromosome Mutations: Types and causes of genome alterations
Spontaneous mutations/deamination/mutagens/cross-linking: Examples of mutation-inducing factors
Dimers/cross links: DNA damages and repair

Gene Concept

Gene definitions in prokaryotes and eukaryotes: How genes operate in each organism

Control of Gene Activity in Prokaryotes

Operon/lactose operon/trp operon/substrate induction/regulated genes/constitutive genes: Key concepts in prokaryotic gene regulation

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Test your knowledge on the role of DNA in transcription, its structure, and important discoveries about genetic material. This quiz covers key concepts and historical experiments that shaped our understanding of genetics and molecular biology.