Chapter 25: Eukaryotic DNA Replication

Question 1

Activities of eukaryotic DNA polymerases?

Answer 1

DNA polymerases α, δ, and ε are involved in eukaryotic nuclear DNA replication.
All these DNA polymerases catalyze DNA synthesis in the 5’→3’ direction.

Pol δ, and ε lacks primase activity but exhibits 3’→5’ exonuclease activity.

DNA polymerase α tightly associates with primase but lacks exonuclease activity

Question 2

Processivites of eukaryotic DNA polymerases?

Answer 2

Pol δ, only high processivity when it is in complex with a PCNA protein.

Pol ε has has high processivity in the absence of PCNA

Pol α has low processivity, involved in initiation of replication.

Question 3

PCNA protein is structurally nearly identical to? What is its function?

Answer 3

PCNA protein is structurally nearly identical to the sliding clamp (β subunit) of the Pol III holoenzyme and increases the processivity of DNA polymerases.

Question 4

By which eukaryotic DNA polymerase is the leading strand likely to be synthesized?

Answer 4

DNA polymerase ε because of its high processivity without PCNA and essential for replication, whereas DNA polymerase α and δ cooperate to synthesize the lagging strand

Question 5

What is the template of reverse transcriptase?

Question 6

What kind of RNA can be destroyed by RNaseH?

Answer 6

RNase that recognize RNA in an RNA-DNA hybrid

Question 7

What is MCM function?
What is RPA?
What is RNase H1?
What is FEN1?

Answer 7

: heterohexameric helicase

replication protein A, a SSB protein

removes RNA primers

flap endonuclease-1, removing the last residue of RNA primer and few nts that is synthesized by Pol α, functioning as a proofreading endonuclease for Pol α

Question 8

Do Eukaryotic chromosome contains single or multiple replication origins?

Answer 8

multiple

Question 9

What is Origins of replication?

Answer 9

the specific sites at which DNA unwinding and initiation of replication occur.

Question 10

The definition of replicon.

Answer 10

all the DNA replicated from a particular origin. The single chromosome in E. coli has only one origin of replication, the entire chromosome is a single replicon. multiple origins exist in each eukaryotic chromosome and divide it into multiple replicons.

Question 11

What is the end replication problem during the replication of eukaryotic linear chromosome?