RNA Primers and DNA Replication
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Questions and Answers

Which process involves the separation of sister chromatids during cell division?

  • Mitosis (correct)
  • DNA replication
  • DNA repair
  • Cytokinesis

When does DNA synthesis occur during the cell cycle?

  • G1 phase
  • M phase
  • S phase (correct)
  • Interphase

Why is accurate DNA replication important for cells?

  • To distribute genetic material to daughter cells
  • To prevent genetic mutations (correct)
  • To repair damaged DNA
  • To ensure proper cell division

What are sister chromatids?

<p>Duplicated chromosomes attached to each other (B)</p> Signup and view all the answers

Which enzyme is responsible for unwinding the DNA strands during replication in E. coli?

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

Which protein complex binds the replication origin in eukaryotes?

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

What is the direction of DNA synthesis during replication?

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

What is the function of the prereplication complex in eukaryotes?

<p>License replication origins (C)</p> Signup and view all the answers

Which enzyme is responsible for joining the Okazaki fragments during DNA replication?

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

What is the direction of synthesis for the leading strand during DNA replication?

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

What is the role of RNA primers in DNA replication?

<p>To initiate DNA synthesis (D)</p> Signup and view all the answers

Which enzyme is responsible for proofreading during DNA replication?

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

Which enzyme is responsible for DNA synthesis in both bacteria and eukaryotes?

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

What is the main function of DNA polymerase I in bacteria?

<p>RNA primer removal and replacement (A)</p> Signup and view all the answers

Which protein is responsible for unwinding double-stranded DNA in both bacteria and eukaryotes?

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

Which enzyme is involved in joining adjacent DNA strands in both bacteria and eukaryotes?

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

Which enzyme is responsible for removing the RNA primer during DNA replication in E. coli?

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

Which protein is responsible for keeping the DNA unwound and accessible to the replication machinery?

<p>SSB (single-stranded DNA binding protein) (B)</p> Signup and view all the answers

What is the key enzyme for DNA replication in E. coli?

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

What is the protein complex called that includes the clamp loader, sliding clamp, and DNA polymerase linked together?

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

Which model of DNA replication suggests that the parent molecule is intact and a completely new copy is made?

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

What is the key suggestion of the Watson and Crick model of DNA replication?

<p>DNA replication is semiconservative (D)</p> Signup and view all the answers

How did Matthew Meselson and Franklin Stahl demonstrate that DNA replication is semiconservative?

<p>By using 14N and 15N to distinguish newly formed DNA strands from old strands (A)</p> Signup and view all the answers

In E. coli, how does DNA replication proceed?

<p>In a bidirectional manner (B)</p> Signup and view all the answers

Which of the following statements about the leading and lagging strands in DNA replication is correct?

<p>The sliding clamp and polymerase remain attached to the leading strand throughout replication. (C)</p> Signup and view all the answers

Which protein acts along with DNA polymerase in eukaryotes during DNA replication?

<p>Proliferating nuclear cell antigen (PCNA) (B)</p> Signup and view all the answers

What is the role of RNAse H in eukaryotic DNA replication?

<p>To nick the backbone of the RNA-DNA hybrid (D)</p> Signup and view all the answers

What is the function of FEN1 in eukaryotic DNA replication?

<p>To remove the RNA primer (B)</p> Signup and view all the answers

What are replication factories in DNA replication?

<p>Structures that coordinate multiple origins of replication (B)</p> Signup and view all the answers

How are chromatin fibers unfolded ahead of the replication fork during DNA replication?

<p>By chromatin remodeling proteins (C)</p> Signup and view all the answers

Flashcards

Mitosis

The process where duplicated chromosomes separate, resulting in two daughter cells, each with a full set of chromosomes.

S phase

The phase of the cell cycle where DNA replication occurs. It happens before the cell divides.

Why is accurate DNA replication important?

Accurate DNA replication is crucial for ensuring that genetic information is passed on correctly to daughter cells, preventing mutations in the genome.

Sister chromatids

Two identical copies of a chromosome, joined together at the centromere, formed during DNA replication.

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DnaB

An enzyme that unwinds the DNA double helix during replication in E. coli, separating the two strands to allow for copying.

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ORC (Origin Recognition Complex)

A protein complex in eukaryotes that recognizes and binds to the origin of replication on DNA, initiating the replication process.

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Direction of DNA synthesis

The directional synthesis of DNA always proceeds in this direction, adding new nucleotides to the 3' end of a growing strand.

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Prereplication complex

A process in eukaryotes that ensures that each origin of replication is only activated once per cell cycle, preventing over-replication.

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DNA ligase

An enzyme essential for DNA replication that joins the short DNA fragments (Okazaki fragments) synthesized on the lagging strand, creating a continuous strand.

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Leading strand

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

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RNA primers

Short RNA segments that provide a starting point for DNA polymerase to begin synthesizing a new DNA strand.

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DNA polymerase

An enzyme that adds nucleotides to a growing DNA chain, but also has a proofreading function to correct errors.

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DNA polymerase III

A primary enzyme that is also responsible for DNA synthesis in both bacteria and eukaryotic cells.

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DNA Polymerase I

This enzyme specifically removes the RNA primer from a newly synthesized DNA strand in bacteria and replaces it with DNA.

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DNA helicase

A protein that unwinds the double-stranded DNA helix in both bacteria and eukaryotes, separating the strands to allow for replication.

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DNA ligase

This enzyme joins adjacent DNA strands in both bacteria and eukaryotic cells, creating a continuous DNA molecule.

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DNA polymerase I

This enzyme removes the RNA primer in E. coli, replacing it with DNA using its 5' to 3' exonuclease activity.

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SSB (Single-stranded DNA Binding protein)

A protein that binds to single-stranded DNA during replication, preventing it from re-forming a double helix and keeping it accessible for replication.

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Gyrase

An enzyme responsible for relieving tension or strain ahead of the replication fork generated as DNA unwinds, preventing the DNA from becoming tangled.

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Holoenzyme

A complex of proteins including the clamp loader, sliding clamp, and DNA polymerase, which function together as a unit during DNA replication.

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Conservative replication

This model of DNA replication proposed that the original parent DNA molecule remained intact, and a completely new copy was made.

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Semiconservative replication

The model proposed by Watson and Crick describing DNA replication, where each new DNA molecule contains one strand from the original molecule and one newly synthesized strand.

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Meselson and Stahl experiment

Meselson and Stahl used heavy nitrogen isotopes to track the origins of DNA strands during replication, demonstrating that the new DNA had one strand from the original DNA and one newly synthesized strand.

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Bidirectional DNA replication

In E. coli, DNA replication proceeds in two directions simultaneously, starting at the origin of replication and moving in opposite directions.

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Difference between leading and lagging strand

The leading strand is continuously synthesized in the same direction as the replication fork movement, while the lagging strand is synthesized in short fragments called Okazaki fragments.

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PCNA (Proliferating cell nuclear antigen)

This protein in eukaryotes functions as a sliding clamp, keeping DNA polymerase attached to the DNA strand throughout replication.

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RNAse H

An enzyme in eukaryotes that removes the RNA primer from the newly synthesized DNA strand during replication.

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FEN1

A protein that removes the RNA primer during eukaryotic DNA replication, by nicking the DNA backbone, and releasing the primer.

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Replication factories

Structures in the nucleus where multiple origins of replication are coordinated, creating a factory-like environment for DNA replication.

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Chromatin remodeling proteins

To properly access DNA for replication, chromatin fibers must be unfolded by these proteins, making the DNA accessible to the replication machinery.

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