DNA Replication Fork Concepts

Questions and Answers

What is the function of helicase?

Opens the DNA for replication (correct)

Reads the DNA template strand

Joins Okazaki fragments

Synthesizes the new DNA strand

What does DNA Polymerase III do?

Reads the DNA template strand 3'-5' and synthesizes the new strand 5'-3'

What characterizes the leading strand in DNA replication?

Strand of freshly copied DNA which is continuously made

What is the lagging strand?

The strand in replication that is copied 3' to 5' as Okazaki fragments Signup and view all the answers

What does topoisomerase do?

Relieves tension ahead of helicase for smooth strand separation Signup and view all the answers

What role does Single-Stranded Binding Protein play in DNA replication?

Prevents DNA from rebinding with itself so replication can occur Signup and view all the answers

What is the function of RNA primase?

Primes the lagging strand for replication with an RNA primer Signup and view all the answers

What is an Okazaki fragment?

Piece of lagging strand before it is joined with rest of lagging strand Signup and view all the answers

What does DNA Polymerase I do?

Replaces RNA primers with DNA Signup and view all the answers

What is ligase and its role in DNA replication?

An enzyme that connects two fragments of DNA to make a single fragment Signup and view all the answers

What is a parent strand in DNA replication?

DNA strand(s) being copied Signup and view all the answers

What is an RNA primer?

Sequence of RNA nucleotides bound to a region of single-stranded DNA to initiate DNA replication Signup and view all the answers

Study Notes

DNA Replication Fork Components

Helicase: Enzyme responsible for unwinding the double helix structure of DNA, enabling replication.
DNA Polymerase 3: Enzyme that reads the template strand in the 3' to 5' direction and synthesizes the new DNA strand in the 5' to 3' direction.

DNA Strands

Leading Strand: Continuously synthesized strand of DNA that is formed in the same direction as the replication fork opens.
Lagging Strand: Synthesized in short segments (Okazaki fragments) in the opposite direction of the replication fork, from 3' to 5'.

Enzymatic Functions

Topoisomerase: Relieves molecular tension ahead of the replication fork, facilitating easier strand separation.
Single-Stranded Binding Protein: Binds to single-stranded regions of DNA to prevent strands from re-annealing, allowing for successful replication.
RNA Primase: Synthesizes a short RNA primer on the lagging strand to initiate DNA synthesis.

Fragmentation in Lagging Strand

Okazaki Fragment: Short sequences of DNA synthesized on the lagging strand between RNA primers, eventually joined to form a continuous strand.

RNA and DNA Replacement

DNA Polymerase 1: Enzyme that replaces RNA primers with DNA after synthesis, ensuring that the final product is entirely DNA.
Ligase: Enzyme that seals the gaps between Okazaki fragments, joining them into a continuous DNA strand.

Key Terminology

Parent Strand: Original DNA strands that serve as templates for replication.
RNA Primer: Short sequence of RNA nucleotides that provides a starting point for DNA synthesis.

Description

Explore the key terms and definitions related to DNA replication, including the roles of helicase, DNA polymerase, leading strands, and lagging strands. This quiz is designed to enhance your understanding of molecular biology and the mechanisms of DNA replication.