Microbial Genetics Overview Quiz
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Questions and Answers

Which strand of DNA has the same sequence as the mRNA?

  • Both A and B
  • Coding strand (correct)
  • Template strand
  • No strand has the same sequence

    • What is the role of the A site in the ribosome during translation?

  • Selects the correct tRNA for the codon read (correct)
  • Ejects empty tRNA
  • Binds the mRNA transcript
  • Holds the growing polypeptide chain

    • What occurs when a stop codon is reached during translation?

  • Transcription is initiated
  • Polypeptide chain is released (correct)
  • A new mRNA strand is synthesized
  • Ribosome continues translating

    • Which type of gene is always transcribed?

    <p>Constitutive gene</p> Signup and view all the answers

    In the operon model, what is the function of the operator site?

    <p>Binding site for the repressor protein</p> Signup and view all the answers

    Which type of operon is activated in response to environmental changes?

    <p>Inducible operon</p> Signup and view all the answers

    What triggers transcription activation in the lac operon?

    <p>Absence of glucose</p> Signup and view all the answers

    How does the ribosome behave after releasing the polypeptide chain?

    <p>Shuffles to the next start codon</p> Signup and view all the answers

    What happens to the trp operon in the absence of tryptophan?

    <p>The RNA polymerase transcribes the operon.</p> Signup and view all the answers

    Which of the following best describes a repressible operon?

    <p>Only active when certain environmental conditions are absent.</p> Signup and view all the answers

    How do spontaneous mutations primarily occur?

    <p>As a result of replication errors.</p> Signup and view all the answers

    What was the outcome when HIV was subjected to increasing amounts of antiviral drugs in the laboratory?

    <p>A highly resistant strain with six mutations emerged.</p> Signup and view all the answers

    What is the typical frequency of replication errors that lead to spontaneous mutations?

    <p>One in a million replicated genes.</p> Signup and view all the answers

    Which of the following statements is true regarding HIV and antiviral drugs?

    <p>HIV can evolve quickly in response to treatment.</p> Signup and view all the answers

    What is the primary effect of mutations on pathogens?

    <p>Mutations can be beneficial, neutral, or deleterious.</p> Signup and view all the answers

    What causes chemical mutations in organisms?

    <p>Exposure to chemical mutagens.</p> Signup and view all the answers

    What is the role of the anticodon on tRNA?

    <p>To bind with the codon on mRNA</p> Signup and view all the answers

    Which component of the ribosome catalyzes the formation of peptide bonds?

    <p>Large ribosomal subunit</p> Signup and view all the answers

    What happens during the initiation stage of transcription?

    <p>DNA unwinds at the promoter region</p> Signup and view all the answers

    What is the reason for having 64 codon combinations for only 20 amino acids?

    <p>Degeneracy protects cells from minor errors</p> Signup and view all the answers

    Which of the following statements about eukaryotic ribosomes is true?

    <p>They consist of a small subunit of 40S</p> Signup and view all the answers

    During transcription, which direction does RNA polymerase read the DNA?

    <p>5’ to 3’ direction</p> Signup and view all the answers

    What initiates the termination of transcription?

    <p>Crossing of a termination sequence by RNA polymerase</p> Signup and view all the answers

    What distinguishes the coding strand from the template strand of DNA?

    <p>The coding strand has a complementary sequence to the mRNA</p> Signup and view all the answers

    What is the primary function of ribosomal RNA (rRNA) in protein synthesis?

    <p>To facilitate the interaction between tRNA and mRNA</p> Signup and view all the answers

    Which of the following correctly describes the Svedberg (S) values of prokaryotic ribosomes?

    <p>70S total, with 30S small and 50S large</p> Signup and view all the answers

    What does a nonsense mutation result in?

    <p>An incomplete protein due to RNA polymerase stopping</p> Signup and view all the answers

    What is the primary purpose of plasmids in bacteria?

    <p>To carry genes for antibiotic resistance or virulence factors</p> Signup and view all the answers

    How does transduction occur in bacteria?

    <p>Via bacteriophage integrating into the bacterial chromosome</p> Signup and view all the answers

    Which mutation type results in a different amino acid being incorporated?

    <p>Missense mutation</p> Signup and view all the answers

    What happens during the process of conjugation?

    <p>DNA is transferred between two bacterial cells through cell contact</p> Signup and view all the answers

    What is a common effect of a frameshift mutation?

    <p>It may alter the phenotype by creating incomplete proteins</p> Signup and view all the answers

    Which of the following describes transformation in bacteria?

    <p>Direct uptake of 'naked' DNA from the environment</p> Signup and view all the answers

    What might integrated viral genes (prophages) code for?

    <p>Virulence factors or antibiotic resistance</p> Signup and view all the answers

    What characterizes a silent mutation?

    <p>A mutation that produces no change in the amino acid</p> Signup and view all the answers

    Which of the following is true regarding bacterial recombination?

    <p>It can generate new genetic combinations in bacteria</p> Signup and view all the answers

    What is the role of DNA polymerase during DNA replication?

    <p>It adds new complementary nucleotides to the existing strand.</p> Signup and view all the answers

    Which of the following describes the lagging strand during DNA replication?

    <p>It is synthesized in short sections called Okazaki fragments.</p> Signup and view all the answers

    What is the purpose of transcription in microbial genetics?

    <p>To transfer genetic code from DNA to messenger RNA.</p> Signup and view all the answers

    What differentiates RNA from DNA?

    <p>RNA has uracil instead of thymine.</p> Signup and view all the answers

    What is referred to as the triplet code in messenger RNA?

    <p>The grouping of three nucleotides that specify an amino acid.</p> Signup and view all the answers

    In DNA replication, what is meant by semiconservative replication?

    <p>Each new double-helix consists of one original and one new strand.</p> Signup and view all the answers

    What role does RNA polymerase play in transcription?

    <p>It synthesizes RNA by reading the DNA template.</p> Signup and view all the answers

    Which of the following correctly describes a codon?

    <p>A set of three nucleotides on mRNA that codes for a specific amino acid.</p> Signup and view all the answers

    Which factors can affect gene regulation and expression?

    <p>Environmental signals and operon configurations.</p> Signup and view all the answers

    What is the function of ligase in DNA replication?

    <p>To join Okazaki fragments together.</p> Signup and view all the answers

    What is a key feature of the structure of DNA?

    <p>It has antiparallel strands oriented 5' to 3'.</p> Signup and view all the answers

    What type of genetic transfer occurs when DNA is taken up from the environment by a cell?

    <p>Transformation</p> Signup and view all the answers

    In terms of mutations, which of the following statements is TRUE?

    <p>Mutations can lead to genetic variation in organisms.</p> Signup and view all the answers

    What are inducer molecules in gene regulation?

    <p>Molecules that inhibit the action of repressors.</p> Signup and view all the answers

    What is the function of tRNA in the protein synthesis process?

    <p>To transfer amino acids to the ribosome.</p> Signup and view all the answers

    Study Notes

    Microbial Genetics Overview

    • Microbial genetics involves the study of genetic material in microorganisms, focusing on structure, function, gene replication, expression, and variation.
    • Key terms include genome, transcription, translation, mutation, and more.

    Structure and Function of Genetic Material

    • DNA is a double-stranded helix made of nucleotides (A, T, G, C) with a deoxyribose sugar backbone.
    • RNA consists of single-stranded nucleotides (A, U, G, C) with ribose sugar; it has distinct forms: mRNA, tRNA, and rRNA.

    Transcription and Translation

    • Transcription transfers genetic code from DNA to mRNA via RNA polymerase, creating mRNA as a complementary strand.
    • mRNA contains codons (triplets of nucleotides) specifying amino acids for protein synthesis, with a specific reading frame essential for proper translation.

    Translation Mechanism

    • Translation occurs at ribosomes with three sites: A (aminoacyl), P (peptidyl), and E (exit) for tRNA binding.
    • Stops codons in mRNA signal the end of polypeptide synthesis, leading to the release of the polypeptide chain.

    Gene Regulation and Operons

    • Genes can be constitutive (always transcribed), inducible (turned on by environmental factors), or repressible (turned off in certain conditions).
    • Operons, clusters of related genes, are regulated as a unit; examples include the lac operon (inducible) and trp operon (repressible).

    DNA Replication Process

    • DNA replication is semiconservative, combining one old strand with one new strand.
    • Leading strand grows towards the replication fork, while the lagging strand synthesizes short Okazaki fragments, later joined by DNA ligase.

    Mutations

    • Mutations are changes in nucleotide sequences, affecting phenotypes, and can arise from spontaneous errors, chemical mutagens, or radiation.
    • Types include base substitution (silent, missense, nonsense mutations) and frameshift mutations (caused by insertions or deletions).

    Genetic Transfer Mechanisms

    • Plasmids are small, circular DNA molecules apart from chromosomal DNA, often carrying antibiotic resistance genes.
    • Genetic recombination methods include conjugation (direct transfer via sex pilus), transformation (uptake of naked DNA), and transduction (transfer via bacteriophages).

    Importance of Genetic Variation

    • Bacterial genetic variation is crucial for adapting to environmental pressures, including antibiotic resistance, allowing populations to evolve rapidly under selective pressures.

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    Related Documents

    U.S. Army Medical Center of Excellence Interservice Physician Assistant Program Block 2-1 Microbial Genetics PDF

    Description

    Test your knowledge on microbial genetics, covering key concepts such as the structure and function of DNA and RNA, transcription, and translation processes. This quiz will assess your understanding of genetic material in microorganisms and the mechanisms of gene expression and replication.

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