BIOL/MCBL 121 Lecture 4 Microbiology Genomes and Replication Quiz
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Questions and Answers

What is responsible for removing the RNA primers in DNA replication?

  • DNA polymerase III
  • DNA polymerase I (correct)
  • RNase H
  • DNA primase

What is the function of Topoisomerase IV in DNA replication termination?

  • It catalyzes the formation of Okazaki fragments
  • It removes the RNA primers
  • It synthesizes new DNA pieces following each RNA primer
  • It passes the chromosomes through one another (correct)

What is the main purpose of plasmids in bacterial cells?

  • To synthesize new DNA pieces following each RNA primer
  • To carry genes for antibiotic resistance (correct)
  • To remove RNA primers
  • To assist in DNA replication

What is the role of ParMRC system in plasmid segregation?

<p>It pushes plasmids to opposite ends of the dividing cell (A)</p> Signup and view all the answers

What do plasmids use to ensure their inheritance and maintenance?

<p>Toxin-antitoxin module (A)</p> Signup and view all the answers

What is the function of DNA ligase in DNA replication?

<p>Sealing the junctions in DNA (D)</p> Signup and view all the answers

What is the significance of plasmid segregation systems?

<p>To ensure random segregation to daughter cells (D)</p> Signup and view all the answers

What is the function of ParM in plasmid segregation?

<p>Forming filaments that push plasmids to opposite ends of the dividing cell (B)</p> Signup and view all the answers

What is a replicon in terms of plasmids?

<p>A circular extrachromosomal DNA with its own origin of replication (C)</p> Signup and view all the answers

What is the difference between stringent and relaxed plasmid origins?

<p>Stringent origins replicate only with chromosome (A)</p> Signup and view all the answers

What is the main purpose of a rolling circle replication in plasmids?

<p>To provide 3′-OH for synthesizing a new strand and release the old strand as template to synthesize a new strand (D)</p> Signup and view all the answers

What is the function of DNA helicase in bacterial DNA replication?

<p>Unwinds the two strands of DNA (A)</p> Signup and view all the answers

What is the role of single-stranded DNA binding proteins (SSBs) in bacterial DNA replication?

<p>Keep the single DNA strands apart during DNA synthesis (D)</p> Signup and view all the answers

Why are RNA primers required for DNA replication?

<p>To act as primers for DNA polymerase III (A)</p> Signup and view all the answers

Which enzyme synthesizes small RNA molecules that act as primers for DNA polymerase III?

<p>DNA primase (D)</p> Signup and view all the answers

What is the function of clamp loader and sliding clamps in bacterial DNA replication?

<p>Recruit DNA polymerase III and tether it to the DNA (D)</p> Signup and view all the answers

DNA polymerase III is responsible for:

<p>Synthesizing new DNA strands (A)</p> Signup and view all the answers

Which part of the replisome complex is involved in synthesizing new DNA strands?

<p>DNA polymerase III (C)</p> Signup and view all the answers

What is the function of DNA primase in bacterial DNA replication?

<p>Produces RNA primers (B)</p> Signup and view all the answers

During DNA replication, which enzyme is responsible for removing the RNA primers?

<p>RNase H (B)</p> Signup and view all the answers

What is the main function of Topoisomerase IV in DNA replication termination?

<p>Catalyzing a breaking and re-joining event (C)</p> Signup and view all the answers

In plasmids, what system ensures their inheritance and maintenance by segregating them to opposite ends of the dividing cell?

<p>ParMRC system (B)</p> Signup and view all the answers

What is the significance of plasmid addiction in bacterial cells?

<p>Creates pressure on cells to maintain plasmids (D)</p> Signup and view all the answers

What is a replicon in terms of plasmids?

<p>A segment of DNA that initiates replication (B)</p> Signup and view all the answers

What is the function of rolling circle replication in plasmids?

<p>Synthesizing new DNA strands unidirectionally (C)</p> Signup and view all the answers

Which enzyme synthesizes small RNA molecules that act as primers for DNA polymerase III?

<p>DNA Primase (B)</p> Signup and view all the answers

What is the function of ParM in plasmid segregation?

<p>Pushing plasmids to opposite ends of the dividing cell (A)</p> Signup and view all the answers

What is responsible for removing the RNA primers in DNA replication?

<p>RNase H (B)</p> Signup and view all the answers

How does rolling circle replication start?

<p>At a nick on a single DNA strand (A)</p> Signup and view all the answers

What is the main purpose of plasmids in bacterial cells?

<p>To adapt to changing environments (D)</p> Signup and view all the answers

Which enzyme is responsible for unwinding the two strands of DNA in bacterial DNA replication?

<p>DNA helicase (D)</p> Signup and view all the answers

What is the main role of single-stranded DNA binding proteins (SSBs) in bacterial DNA replication?

<p>Keeping the single DNA strands apart during DNA synthesis (D)</p> Signup and view all the answers

Which enzyme synthesizes small RNA molecules that act as primers for DNA polymerase III in bacterial DNA replication?

<p>DNA primase (A)</p> Signup and view all the answers

What is the function of clamp loader and sliding clamps in bacterial DNA replication?

<p>Recruiting DNA polymerase III and tethering it to the DNA (B)</p> Signup and view all the answers

In bacterial DNA replication, what is the significance of RNA primers?

<p>They provide the 3’-OH group for new DNA strand synthesis (A)</p> Signup and view all the answers

What is the evolutionary remnant related to RNA in bacterial DNA replication?

<p>RNA was the first genetic material (D)</p> Signup and view all the answers

What is replicated via replisome complexes in bacterial DNA replication?

<p>Nucleoid, beginning at the origin of replication (B)</p> Signup and view all the answers

What type of replication does cellular DNA undergo in most cases during bacterial DNA replication?

<p>Conservative replication (A)</p> Signup and view all the answers

What does each daughter cell receive during bacterial cellular DNA replication?

<p>(SSBs) single-stranded DNA binding proteins and parental strands (D)</p> Signup and view all the answers

What is required for DNA replication in bacteria?

<p>(DNA primase) RNA primers (D)</p> Signup and view all the answers

What is responsible for removing the RNA primers in bacterial DNA replication?

<p>DNA polymerase III (C)</p> Signup and view all the answers

What is the main purpose of rolling circle replication in plasmids?

<p>To synthesize new plasmid strands (C)</p> Signup and view all the answers

During plasmid replication, the bidirectional replication is similar to chromosomal replication in that it:

<p>terminates at defined termination (ter) sites located opposite to the origin (D)</p> Signup and view all the answers

What is the significance of the ParMRC system in plasmid segregation?

<p>It ensures high-copy-number plasmids segregate randomly to daughter cells (C)</p> Signup and view all the answers

In plasmids, what is the main role of the toxin-antitoxin module for self-maintenance?

<p>It ensures cells maintain the plasmid by providing a constant source of antitoxin against the plasmid-expressed toxin (C)</p> Signup and view all the answers

What does the topoisomerase IV do during DNA replication termination?

<p>Catalyzes a breaking and re-joining event at defined termination sites (B)</p> Signup and view all the answers

What is the function of rolling circle replication in plasmids?

<p>Starts at a nick on a single DNA strand and provides 3'-OH for synthesizing a new strand (A)</p> Signup and view all the answers

During bacterial DNA replication, which enzyme is responsible for keeping the single DNA strands apart?

<p>DNA helicase (D)</p> Signup and view all the answers

What is the main function of Topoisomerase IV in DNA replication termination?

<p>Ensuring plasmid inheritance and maintenance (C)</p> Signup and view all the answers

What is the main role of single-stranded DNA binding proteins (SSBs) in bacterial DNA replication?

<p>Keeping the single DNA strands apart (C)</p> Signup and view all the answers

What type of replication does cellular DNA undergo in most cases during bacterial DNA replication?

<p>Semiconservative replication (B)</p> Signup and view all the answers

What is required for DNA replication in bacteria?

<p>RNA primers (C)</p> Signup and view all the answers

What is the role of ParMRC system in plasmid segregation?

<p>Segregating plasmids to opposite ends of the dividing cell (A)</p> Signup and view all the answers

What is replicated via replisome complexes in bacterial DNA replication?

<p>Chromosomal DNA only (D)</p> Signup and view all the answers

What is the function of clamp loader and sliding clamps in bacterial DNA replication?

<p>Recruiting DNA polymerase III and tethering it to the DNA (D)</p> Signup and view all the answers

What is responsible for removing the RNA primers in bacterial DNA replication?

<p>DNA ligase (D)</p> Signup and view all the answers

What is the function of rolling circle replication in plasmids?

<p>Increasing plasmid copy number (D)</p> Signup and view all the answers

What does each daughter cell receive during bacterial cellular DNA replication?

<p>One parental and one newly synthesized strand (B)</p> Signup and view all the answers

What is the evolutionary remnant related to RNA in bacterial DNA replication?

<p>The use of RNA as the first genetic material (D)</p> Signup and view all the answers

Flashcards

RNA Primers

Short RNA molecules that provide a starting point for DNA polymerase to begin synthesis.

RNase H

An enzyme that removes RNA primers from the newly synthesized DNA strand.

Primase

An enzyme that synthesizes short RNA molecules that act as primers for DNA polymerase.

DNA Unwinding

The process of unzipping the double helix to separate the two DNA strands during replication.

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DNA Helicase

An enzyme that unwinds the DNA double helix during replication.

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Single-Stranded DNA Binding Proteins (SSBs)

Proteins that bind to single-stranded DNA and prevent it from re-annealing.

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Replisome Complex

A multi-protein structure that replicates DNA in a continuous and efficient manner.

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Rolling Circle Replication

A type of DNA replication where DNA is synthesized in one direction, and one strand is displaced, resulting in multiple copies of the plasmid.

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Bidirectional Replication

A type of replication where DNA synthesis starts at an origin of replication and proceeds bidirectionally.

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Decatenation

The process of removing the knots/intertwines that form during DNA replication.

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Topoisomerase IV

An enzyme that removes catenations between newly replicated DNA molecules during replication.

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Clamp Loader and Sliding Clamps

A complex of proteins, including a clamp loader and sliding clamps, that are responsible for loading DNA polymerase onto the template strand.

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DNA Ligase

An enzyme that joins the Okazaki fragments together, leading to a continuous strand of DNA.

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Plasmids

Small, circular DNA molecules found in bacteria, independent of the main chromosome.

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ParMRC System

A system used by plasmids to ensure they are equally distributed to daughter cells during bacterial division.

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Plasmid Segregation

The function of the ParMRC system is to ensure proper segregation of plasmids to daughter cells during division.

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Main Function of Plasmids

The main purpose of plasmids is to provide a means for genetic exchange and to carry antibiotic resistance genes.

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Okazaki Fragments

Fragments of DNA synthesized on the lagging strand during DNA replication.

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Lagging Strand

The strand of DNA that is synthesized discontinuously in the direction opposite to the replication fork.

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Leading Strand

The strand of DNA continuously synthesized in the same direction as the replication fork.

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Origin of Replication

The point where DNA replication begins.

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Repetitive DNA

Regions of DNA that are repeated in the genome.

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Origin Recognition Complex

A type of repetitive DNA that serves as a binding site for proteins involved in replication.

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Catenated DNA

DNA that has been replicated and is not yet separated.

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RNA Primers as Evolutionary Remnants

RNA primers are a remnant of an ancient era when RNA served as the primary genetic material.

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Non-Coding DNA

Short sequences of DNA that are not transcribed into proteins.

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Regulatory Elements

A type of non-coding DNA that can regulate gene expression by binding to proteins.

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Protein Synthesis

The process of using information encoded in DNA to produce functional protein molecules.

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Transcription

The process of copying the genetic information from DNA into RNA.

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Translation

The process of translating the genetic information encoded in RNA into a specific protein sequence.

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Polymerization

The process of building complex molecules like proteins from simpler subunits.

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Cell Division

The process of replicating DNA and dividing the chromosomes into two daughter cells.

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Study Notes

DNA Replication

  • RNA primers are removed by RNase H.
  • RNA primers are required for DNA replication because they provide a starting point for DNA synthesis.
  • Primase synthesizes small RNA molecules that act as primers for DNA polymerase III.

DNA Replication Termination

  • Topoisomerase IV is responsible for removing catenations between newly replicated DNA molecules.

Plasmids

  • Plasmids are small, self-replicating circular DNA molecules found in bacterial cells.
  • The main purpose of plasmids is to provide a means for genetic exchange and to carry antibiotic resistance genes.
  • Plasmids use the ParMRC system to ensure their inheritance and maintenance by segregating them to opposite ends of the dividing cell.
  • The ParMRC system ensures plasmid segregation by anchoring the plasmid to the cell membrane and then moving it to the opposite end of the cell.
  • Plasmid segregation systems are significant because they ensure the stable inheritance of plasmids.

Replication Methods

  • Rolling circle replication is a method of replication used by some plasmids, where one strand of DNA is continuously synthesized while the other strand is displaced.
  • The main purpose of rolling circle replication is to rapidly produce multiple copies of the plasmid.
  • Bidirectional replication is similar to chromosomal replication, where two replication forks move in opposite directions.

Enzymes and Proteins

  • DNA helicase unwinds the two strands of DNA during bacterial DNA replication.
  • Single-stranded DNA binding proteins (SSBs) keep the single DNA strands apart and prevent them from re-annealing.
  • Clamp loader and sliding clamps are responsible for loading the DNA polymerase onto the template strand.
  • DNA ligase is responsible for sealing the gaps between Okazaki fragments.
  • Topoisomerase IV is responsible for removing catenations between newly replicated DNA molecules.

Replisome Complex

  • The replisome complex is responsible for synthesizing new DNA strands.
  • Replisome complexes replicate the DNA molecule in a processive manner.

Evolutionary Remnants

  • RNA primers are an evolutionary remnant related to RNA in bacterial DNA replication.

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MCBL121 Lecture 4: Genomes and Replication PDF

Description

Test your knowledge about the process of chromosomal and plasmid replication in bacteria, as well as evolutionary strategies for plasmid maintenance. Explore the concepts related to bacterial DNA replication and the semiconservative nature of cellular DNA replication.

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