DNA Replication in Prokaryotes Lecture Quiz

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Questions and Answers

What is the function of DNA replication?

To provide genetic information required by the daughter cell from the parent cell (correct)

To produce genetic information for the parent cell

To create a completely new set of genetic information

To repair damaged DNA strands

Which direction does DNA polymerase synthesize the new strand?

5' to 3' (correct)

From the middle to the ends

In a random direction

3' to 5'

What is the role of DNA helicase in replication?

Unwinds the DNA double helix (correct)

Adds nucleotides to a free single stranded DNA template

Joins ends of two segments of DNA

Catalyzes the synthesis of DNA strands

Why do DNA polymerases require an RNA primer?

To facilitate the synthesis of the lagging strand Signup and view all the answers

What is the role of DNA ligase in replication?

Joins ends of two segments of DNA Signup and view all the answers

What is meant by semi-conservative replication?

Each daughter DNA molecule consists of one old strand and one new strand Signup and view all the answers

Which enzyme catalyzes the removal of supercoils formed during DNA unwinding?

DNA gyrase Signup and view all the answers

What is the function of DNA topoisomerase I in DNA replication?

Allows the intact strand to pass through a nick in the other strand Signup and view all the answers

Which enzyme is responsible for producing progressive unwinding of the DNA double helix at the replication fork?

Helicase Signup and view all the answers

What is the role of single-strand binding (SSB) proteins in DNA replication?

Stabilizing the single strands and protecting them from nucleases Signup and view all the answers

Which enzyme is responsible for forming RNA primers during DNA replication?

Primase Signup and view all the answers

What is the function of DNA polymerase III in DNA replication?

Synthesizes both strands of DNA Signup and view all the answers

Which characteristic property of DNA polymerase III allows it to synthesize both strands of DNA at a high rate?

High processivity up to 50,000 nucleotides in one cycle Signup and view all the answers

Which enzyme acts by making transient breaks in both DNA strands during DNA replication?

DNA topoisomerase II Signup and view all the answers

What is the role of dna A in DNA replication in prokaryotes?

It binds to ori C and produces local unwinding. Signup and view all the answers

What is the function of DNA gyrase in bacteria and plants?

It introduces negative supercoils to relaxed circular DNA using energy. Signup and view all the answers

Study Notes

DNA Replication Overview

DNA replication is essential for cell division, ensuring that each daughter cell receives an exact copy of the DNA.
It is a semi-conservative process, meaning each new double helix contains one original strand and one newly synthesized strand.

Direction of Synthesis

DNA polymerase synthesizes new strands in the 5' to 3' direction, adding nucleotides to the 3' end of the growing strand.

Role of DNA Helicase

DNA helicase unwinds the double helix, separating the two strands to allow for replication to occur.

Requirement for RNA Primer

DNA polymerases cannot initiate synthesis on a bare template strand; they require a short RNA primer to provide a starting point for DNA synthesis.

Function of DNA Ligase

DNA ligase seals gaps between Okazaki fragments on the lagging strand, ensuring the continuity of the DNA molecule.

Semi-conservative Replication

In semi-conservative replication, each parent strand serves as a template for a new complementary strand, resulting in two DNA molecules, each with one old and one new strand.

Enzyme for Supercoil Removal

DNA topoisomerase is responsible for relieving the supercoiling tension that occurs ahead of the replication fork during DNA unwinding.

Function of DNA Topoisomerase I

DNA topoisomerase I creates transient single-strand breaks in DNA to alleviate torsional strain generated during replication.

Enzyme for Progressive Unwinding

DNA helicase actively unwinds the DNA double helix at the replication fork, allowing access for other enzymes involved in replication.

Role of Single-Strand Binding (SSB) Proteins

SSB proteins stabilize unwound single strands of DNA, preventing them from re-annealing or forming secondary structures during replication.

RNA Primer Formation

The enzyme primase synthesizes short RNA primers necessary for initiating DNA replication.

Function of DNA Polymerase III

DNA polymerase III is the primary enzyme responsible for synthesizing new DNA strands during replication, working quickly and effectively on both leading and lagging strands.

Characteristics of DNA Polymerase III

The high processivity of DNA polymerase III allows it to synthesize DNA at a rapid rate, making it efficient for replication.

Enzyme for Transient Breaks

DNA topoisomerase II (or gyrase in bacteria) makes transient breaks in both strands of DNA, facilitating the untangling of DNA during replication.

Role of DnaA in Prokaryotes

DnaA is involved in the initiation of DNA replication in prokaryotes by binding to the origin of replication, facilitating the unwinding of DNA.

Function of DNA Gyrase

DNA gyrase is a type of topoisomerase that introduces negative supercoils into DNA, helping to relieve torsional strain in bacterial and plant DNA during replication.

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Description

Test your knowledge on DNA replication in prokaryotes with this quiz based on the lecture by Dr. George N. B. Morcos. Explore the proteins, enzymes, and synthesis of leading and lagging strands involved in DNA replication.