Eukaryote Replication (Gelinas) Flashcards
DNA polymerases involved in eukaryotic DNA replication:
- pol-alpha
- pol-delta
- pol-epsilon
Eukaryotic DNA replication is similar to prokaryotes with the excpetion of (4):
- more DNA to replicate
- multiple points of replication
- different polymerases and proteins involved
- DNA is associated with histones
- telomeres
What eukaryotic DNA polymerase is responsible for primer synthesis?
- pol-alpha
- initiates primer synthesis on leading and lagging strands
- no exonuclease activity
What eukaryotic DNA polymerase is responsible for replication the lagging strand?
pol-delta in association with PCNA
(has exonuclease activity)
What eukaryotic DNA polymerase is responsible for replication the leading strand?
pol-epsilon in association with PCNA
(has nuclease acitivity)
Processivity factor PCNA:
- associates with pol-delta and p-epsilon during DNA replication
Okazaki fragments are displaced by:
pol-delta on the 5’ end
Okazaki fragments are degraded by:
- “flap exonuclease” FEN1
- other nucleases
Telomeres:
- the ends of linear chromosomes in eukaryotes
- short non-coding G-rich repetitive DNA sequences (TTAGGG)
Three main functions of telomeres:
- protect chromosome ends from fusion
- protect chromosome ends from being degraded
- prevent the loss of terminal sequences during replication
Telomerase:
- 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
Telomerase adds short DNA repeats to what ends of linear chromosomes?
- 3’ end of the parent strand
- DNA polymerase then comes in and finishes the synthesis of the lagging strand.