Eukaryote Replication (Gelinas)

Question 1

DNA polymerases involved in eukaryotic DNA replication:

Answer 1

1. pol-alpha
2. pol-delta
3. pol-epsilon

Question 2

Eukaryotic DNA replication is similar to prokaryotes with the excpetion of (4):

Answer 2

1. more DNA to replicate
2. multiple points of replication
3. different polymerases and proteins involved
4. DNA is associated with histones
5. telomeres

Question 3

What eukaryotic DNA polymerase is responsible for primer synthesis?

Answer 3

• pol-alpha
• initiates primer synthesis on leading and lagging strands
• no exonuclease activity

Question 4

What eukaryotic DNA polymerase is responsible for replication the lagging strand?

Answer 4

pol-delta in association with PCNA

(has exonuclease activity)

Question 5

What eukaryotic DNA polymerase is responsible for replication the leading strand?

Answer 5

pol-epsilon in association with PCNA

(has nuclease acitivity)

Question 6

Processivity factor PCNA:

Answer 6

• associates with pol-delta and p-epsilon during DNA replication

Question 7

Okazaki fragments are displaced by:

Answer 7

pol-delta on the 5’ end

Question 8

Okazaki fragments are degraded by:

Answer 8

• “flap exonuclease” FEN1
• other nucleases

Question 9

Telomeres:

Answer 9

• the ends of linear chromosomes in eukaryotes
• short non-coding G-rich repetitive DNA sequences (TTAGGG)

Question 10

Three main functions of telomeres:

Answer 10

1. protect chromosome ends from fusion
2. protect chromosome ends from being degraded
3. prevent the loss of terminal sequences during replication

Question 11

Telomerase:

Answer 11

• ribonucleoprotein complex (RNA + protein)
• reverse transcriptase activity (hTERT): it synthesizes DNA using its RNA subunit as the template
• adds short DNA repeats to the 3ʼ-ends of linear chromosomes

Question 12

Telomerase adds short DNA repeats to what ends of linear chromosomes?

Answer 12

• 3’ end of the parent strand
• DNA polymerase then comes in and finishes the synthesis of the lagging strand.