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Nucleic Acids > Replication > Flashcards

Flashcards in Replication Deck (17):
1

Helicase role

unwinding the double helix

2

Primase role

synthesis of primers

3

Single-stranded binding protein (SSB) role

stabilising single-stranded regions

4

Topoisomerase role

release of topological stress

5

DNA polymerase role

DNA synthesis

6

5'-3' exonuclease role

primer removal

7

Ligase role

joining of okazaki fragments

8

Four steps of initiation

1. recognition of replication origin
2. partial unwinding of DNA helix
3. Helicase entry, strand separation
4. primer synthesis

9

E.coli replication origin (name, no. of bps, repetitive sequences)

-OriC
-240 bp
-9 mer x4 (DNAa binding site)
13 mer x3 (DNAb binding site)

10

3 things that make DNA synthesis in eukaryotes more complicated than in prokaryotes

1. Much bigger genome (e.g. E.coli: 4mil bp Human: 6bil bp)
2. More chromosomes (e.g. E. coli: 1 Humans: 23)
3. Linear chromosomes

11

Processicivity

capacity of an enzyme to stay bound to its substrate

12

DNApol I enzyme activities

1. polymerisation
2. 3' - 5' exonuclease activity
3. 5' - 3' exonuclease activity

13

DNApol II enzyme activities

1. polymerisation
2. 3' - 5' exonuclease activity

14

DNApol III enzyme activities

1. polymerisation
2. 3' - 5' exonuclease activity

15

E. coli polymerase III properties

1. >600 kD, 10 polymers
2. 750 nucleotides per sec

16

E. coli polymerase III functional components

1. core polymerase
2. sliding clamp
3. clamp loader
4. tau subunit

17

Polymerase switching

after the polα/primase complex synthesises a 10nt primer and extends it 15nt, Replication Factor C displaces it and loads PCNA onto the template allowing pol 𝛿 to continue extending the primer