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:
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?
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What is the stringent response mediated by?
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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?
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The term diauxic growth is used to describe what situation?
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Why doesn't the arginine repressor ArgR bind DNA without its corepressor?
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Since genes are arranged in operons in prokaryotes, what does it allow for?
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If you're studying a DNA-binding protein that interacts with the DNA sugar-phosphate backbone, what do you expect?
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Does RNA polymerase need all 5 subunits (alpha, beta, beta prime, omega, sigma) to create RNA?
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In which direction does DNA polymerase synthesize a new strand of DNA?
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Can SARS-CoV-2 integrate into human cells (effectively undergo lysogeny)?
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The SARS-CoV-2 viron membrane is derived from ____, while the SARS-CoV-2 viron proteins are derived from ____.
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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?
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How might a transposon or insertion element get into a microbial genome?
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What might be a beneficial outcome of horizontal gene transfer for a microbe?
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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?
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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?
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Do all mutations result in visible phenotypes?
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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.
Studying That Suits You
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Description
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.