CMB211 Unit 2 Flashcards
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Questions and Answers

How many plasmids are likely to be found in a single bacterial cell?

0-100

How many chromosomes are likely to be found in a single bacterial cell?

1

SRNAs can regulate gene expression by:

  • Increasing mRNA degradation, inhibiting translation (correct)
  • Promoting mRNA translation directly (correct)
  • Inhibiting mRNA translation directly (correct)
  • Inhibiting mRNA degradation, promoting translation (correct)
  • In a two-component regulatory system, what would happen if the phosphatase is modified so it can no longer remove phosphate from the response regulator?

    <p>Cells will behave as if there is always an external signal</p> Signup and view all the answers

    What is the stringent response mediated by?

    <p>All of the above</p> Signup and view all the answers

    What would best describe transcription of the lac operon if the LacI protein has been mutated so it can't bind the lac operator sequences?

    <p>Always at least a small amount of lac operon expression</p> Signup and view all the answers

    The term diauxic growth is used to describe what situation?

    <p>Bacteria have access to two carbon sources but always use their preferred carbon source first before using the second carbon source.</p> Signup and view all the answers

    Why doesn't the arginine repressor ArgR bind DNA without its corepressor?

    <p>ArgR undergoes a conformational change that allows it to bind DNA only after it interacts with its corepressor.</p> Signup and view all the answers

    Since genes are arranged in operons in prokaryotes, what does it allow for?

    <p>Regulation of multiple genes at the same time to achieve a coordinated response</p> Signup and view all the answers

    If you're studying a DNA-binding protein that interacts with the DNA sugar-phosphate backbone, what do you expect?

    <p>To DNA non-specifically</p> Signup and view all the answers

    Does RNA polymerase need all 5 subunits (alpha, beta, beta prime, omega, sigma) to create RNA?

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

    In which direction does DNA polymerase synthesize a new strand of DNA?

    <p>5' -&gt; 3'</p> Signup and view all the answers

    Can SARS-CoV-2 integrate into human cells (effectively undergo lysogeny)?

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

    The SARS-CoV-2 viron membrane is derived from ____, while the SARS-CoV-2 viron proteins are derived from ____.

    <p>Host cell membrane / viral proteins</p> Signup and view all the answers

    Will a bacterium with a CRISPR system, whose ancestor was exposed to a particular virus, be able to survive another infection attempt by the same virus?

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

    How might a transposon or insertion element get into a microbial genome?

    <p>All of the above</p> Signup and view all the answers

    What might be a beneficial outcome of horizontal gene transfer for a microbe?

    <p>All of the above</p> Signup and view all the answers

    Where is a likely spot recombination might occur if a bacterium has taken up DNA from a bacterium that isn't very closely related to it?

    <p>At ribosomal RNA genes</p> Signup and view all the answers

    What kind of mutation would occur if your gene has the following codons: AGG GTC TAT TCC ATA and before the last codon, these two base pairs are inserted: TG?

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

    Do all mutations result in visible phenotypes?

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

    Study Notes

    Plasmids and Chromosomes

    • A single bacterial cell can contain between 0 to 100 plasmids.
    • Typically, bacterial cells possess one chromosome.

    Gene Regulation by sRNAs

    • Small RNAs (sRNAs) regulate gene expression through various mechanisms, including:
      • Direct inhibition or promotion of mRNA translation.
      • Modulation of mRNA degradation and stability.

    Two-Component Regulatory Systems

    • If the phosphatase in a two-component system cannot remove phosphate from the response regulator, cells act as if an external signal is perpetually present.

    Stringent Response

    • Triggered by nutrient limitation, results in synthesis of ppGpp and pppGpp.
    • Varies in its outcomes based on the organism experiencing stress.

    Lac Operon Regulation

    • A mutation preventing LacI protein from binding the lac operator leads to consistent low-level expression of the lac operon.

    Diauxic Growth

    • Describes bacterial growth in the presence of two carbon sources, where the preferred source is utilized first, followed by the secondary source.

    Arginine Repressor Function

    • ArgR only binds DNA with corepressor arginine due to a conformational change required for DNA interaction.

    Operons in Prokaryotes

    • Gene arrangement in operons allows simultaneous regulation of multiple genes for a coordinated response to stimuli.

    DNA-binding Protein Interaction

    • A protein interacting with the DNA sugar-phosphate backbone indicates non-specific binding to DNA.

    RNA Polymerase

    • RNA synthesis does not require all five subunits of RNA polymerase; it can function with fewer.

    DNA Polymerase Synthesis Direction

    • Synthesizes new DNA strands in the 5' to 3' direction.

    SARS-CoV-2 Integration

    • SARS-CoV-2 does not integrate into human cells or undergo lysogeny.

    SARS-CoV-2 Viron Structure

    • The viron membrane is derived from the host cell, while proteins are produced from viral sources.

    CRISPR System and Viral Resistance

    • Bacteria with a CRISPR system can withstand future infections from viruses previously encountered by ancestors.

    Horizontal Gene Transfer Benefits

    • Offers microbe advantages like new carbon source utilization, antibiotic resistance, and ecological niche survival.

    Recombination in Genetic Exchange

    • Recombination is likely to occur at ribosomal RNA genes when distant bacteria exchange DNA.

    Mutation Types

    • The insertion of base pairs can lead to a nonsense mutation in a gene's coding sequence.

    Mutations and Phenotypes

    • Not all mutations lead to observable changes in phenotypes.

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    Test your knowledge on plasmids, chromosomes, and sRNAs with these flashcards from CMB211 Unit 2. Each card provides a key concept relevant to bacterial cell structure and gene regulation. Perfect for students looking to reinforce their understanding of molecular biology.

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