Dna Flashcards
What is the function of helicase in DNA replication?
Unwinds parental double helix at replication forks
Helicase is essential for separating the two strands of DNA to allow replication.
What role does single-strand binding protein play during DNA replication?
Binds to and stabilizes single-stranded DNA until it is used as a template
This prevents the single strands from re-annealing or forming secondary structures.
What is the function of topoisomerase (DNA Gyrase) in DNA replication?
Relieves overwinding strain ahead of replication forks by breaking, swiveling, and rejoining DNA strands
This is crucial for preventing torsional strain that could hinder replication.
What is the role of primase in DNA replication?
Synthesizes an RNA primer at 5’ end of leading strand and at 5’ end of each Okazaki fragment of lagging strand
Primase is necessary for providing a starting point for DNA polymerase.
What does DNA polymerase III do during DNA replication?
Using parental DNA as a template, synthesizes new DNA strand by adding nucleotides to an RNA primer or a pre-existing DNA strand
DNA polymerase III is the primary enzyme involved in DNA synthesis.
Fill in the blank: The structure formed by the separation of the two complementary strands of DNA during replication is known as the _______.
replication fork
The replication fork is a Y-shaped structure that is critical for the replication process.
What happens to the RNA primers during DNA replication?
RNA nucleotides of primer are removed from 5’ end and replaced with DNA nucleotides added to 3’ end of adjacent fragment
This ensures that the final DNA strand is made entirely of DNA nucleotides.
What is the function of DNA ligase in DNA replication?
Joins Okazaki fragments of lagging strand and joins 3’ end of DNA that replaces primer to rest of leading strand DNA
DNA ligase is essential for sealing nicks in the sugar-phosphate backbone.
True or False: DNA polymerase can synthesize DNA in both the 5’ to 3’ and 3’ to 5’ directions.
False
DNA polymerase only synthesizes DNA in the 5’ to 3’ direction.
What are Okazaki fragments?
Short segments of DNA synthesized on the lagging strand during DNA replication
These fragments are later joined together by DNA ligase.
What is the direction of DNA synthesis by DNA polymerase?
5’ to 3’
This directionality is crucial for the mechanism of DNA replication.
Fill in the blank: RNA primase enzymes begin the replication process by building a small complementary RNA segment called _______.
RNA primers
RNA primers are typically 10-60 ribonucleotides long.
What is the significance of the leading and lagging strands during DNA replication?
The leading strand is synthesized continuously, while the lagging strand is synthesized in short segments (Okazaki fragments)
This difference is due to the antiparallel nature of DNA strands.
