6.3 DNA Replication Flashcards
1
Q
Replication complex (replisome)
A
- a set of specialized proteins that assist the DNA polymerases
2
Q
Helicase
A
the enzyme responsible for unwinding the DNA, generating two single-stranded template strands ahead of the polymerase
3
Q
DNA topoisomerases
A
- introduce negative supercoils.
They do so by working ahead of helicase, nicking one or both strands, allowing relaxation of the torsional pressure, and then resealing the cut strands - alleviate this torsional stress and reduce the risk of strand breakage
4
Q
Semiconservative
A
- one parental strand is retained in each of the two resulting identical double stranded DNA molecules
5
Q
How does DNA polyermase read the template strand?
A
- read the template strand in a 3′ to 5′ direction while synthesizing the complementary strand in the 5′ to 3′ direction.
6
Q
Which processes occur 5’ to 3’?
A
- DNA synthesis
- DNA repair
- RNA transcription
- RNA translation (reading of codons)
7
Q
Leading strand
A
- stand copied in continuous fashion
8
Q
Lagging Strand
A
- strand that is copied in a direction opposite the
direction of the replication fork.
9
Q
Primase
A
- synthesizes a short primer (roughly 10 nucleotides) in the 5′ to 3′ direction to start replication on each strand
- These short RNA sequences are constantly being added to the lagging strand because each Okazaki fragment
must start with a new primer
10
Q
DNA polymerase III
A
-Synthesizes daughter strands for prokaryotes
11
Q
DNA polymerases α, δ, and ε
A
-Synthesizes daughter strands for eukaryotes
- incoming nucleotides are 5′ deoxyribonucleotide
triphosphates: dATP, dCTP, dGTP, and dTTP
12
Q
DNA polymerase I
A
- prokaryotes
- removes RNA
- adds DNA nucleotides where the RNA primer had been.
13
Q
RNase H
A
- eukaryotes
-removes RNA - adds DNA nucleotides where the RNA primer had been.
14
Q
DNA polymerase δ (Delta)
A
- fills in the gaps left behind when RNA primers are removed
15
Q
DNA polymerase γ (Gamma)
A
replicates mitochondrial DNA
