DNA Replication Flashcards
What is the function of DNA Ligase?
Joins adjacent sections together
DNA Ligase plays a crucial role in sealing nicks in the sugar-phosphate backbone of DNA.
What enzyme binds to the origin of replication and separates DNA strands moving from 3’ to 5’?
Helicase
Helicase is essential for unwinding the DNA double helix during replication.
What is the role of Topoisomerase in DNA replication?
Binds ahead of helicase and uncoils the chromosome
Topoisomerase helps relieve the strain of unwinding the DNA.
What does Primase do in the DNA replication process?
Adds RNA primer at the origin of replication
The RNA primer provides a starting point for DNA synthesis.
What is the function of DNA Polymerase 3?
Binds at the origin of replication and adds DNA nucleotides
DNA Polymerase 3 is the main enzyme responsible for DNA synthesis.
What direction do nucleotides move during DNA replication?
3’ to 5’
This directionality is critical for the synthesis of the new DNA strand.
What are Okazaki fragments?
Short strands of DNA that make up the lagging strands during replication
Okazaki fragments are formed because DNA replication is discontinuous on the lagging strand.
What enzyme replaces RNA with DNA nucleotides in Okazaki fragments?
DNA Polymerase 1
DNA Polymerase 1 is responsible for removing RNA primers and filling in the gaps with DNA.
Fill in the blank: DNA _______ adds RNA nucleotides to the unpaired exposed strand in lagging strand synthesis.
Primase
Primase is essential for initiating the synthesis of Okazaki fragments.
True or False: The leading strand is synthesized continuously.
True
The leading strand is synthesized in a continuous manner towards the replication fork.
True or False: DNA Polymerase 3 can initiate synthesis without a primer.
False
DNA Polymerase 3 requires a primer to initiate DNA synthesis.
What are the pyrimidines?
Thymine, uracil, and cytosine.
Uracil is only found in RNA, while thymine is only found in DNA.
What are the purines?
Adenine and guanine.
How many nucleotides are there per cell?
12 billion nucleotides per cell.
What is the relationship between adenine and thymine?
of A = # of T.
What is the relationship between guanine and cytosine?
of G = # of C.
What are the complementary base pairs?
A-T and C-G.
What are the two jobs of DNA?
- Replication
- Codes for RNA.
When does DNA replication occur?
During the S stage of interphase.
What initiates DNA replication?
Starts at origins of replication (OR).
What is helicase?
An enzyme that separates the two DNA strands and moves 3’→ 5’.
What is the function of Topoisomerase?
Moves ahead of helicase and uncoils the chromosomes.
What does Primase do?
Adds RNA nucleotides to exposed DNA nucleotides at the origin of replication.
What is the role of DNA polymerase 3?
Adds DNA nucleotides to exposed DNA nucleotides in the 3’ to 5’ direction.
What is the function of DNA polymerase 1?
Replaces RNA nucleotides with DNA nucleotides.
What does DNA ligase do?
Joins adjacent sections of DNA.
