Replication of DNA and Chromosomes

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DNA polymerase a has associated primase activity and is thought to be the polymerase that synthesizes the lagging strand.

Slide 13

DNA Synthesis at the Origin

Additional factors:

PCNA (proliferating cell nuclear antigen)

DNA helicase

Replication factor C

OTHERS

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Replication of Nucleosomes

Eukaryotic DNA is packaged with histones in structures called nucleosomes.

What happens to the nucleosome when the replication fork and the replication machinery pass by and open up the DNA double strand?

Nucleosomes are found properly spaced on both postreplicative DNA strands immediately after passage of replication fork.

Slide 15

Slide 16

A model for nucleosome replication

Slide 17

The lagging strand of telomeres cannot be replicated by the usual mechanism

Slide 18

Telomere and Telomerase

Solution:

special telomere sequence: tandem repeats of TTAGGG (human)

telomerase, a specific enzyme with integrated RNA template.

Slide 19

Telomere replication