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Foundations Part II > DNA Replication > Flashcards

Flashcards in DNA Replication Deck (22):
1

Where are the phosphate groups added in dexoxyribose

At the 3' end

2

When does ORC binds to the DNA origin

Late M/early G1 phase

3

What binds to ORC to start trasncription

cdt1 and cdc6

4

What do these factors recruit

MCM helicase units

5

Which factor licenses replication

cdc6

6

What does it do

brings along cdt1 and MCM helicase

7

How does the levels of cdc6, cdt1 and geminin vary

cdc6 rises at the end of G1 phase and stays high until M phase, cdt1 increase at the end of M phase (all the way through G1) and geminin levels are high all the time except when cdt1 levels are high

8

What happens after the MCM complex opens the DNA

DNA primase and DNA pol alpha comes in and the DNA polymerase (DNA epsilon and theta) comes in,.

Topoisomerase loosens up the DNA

9

What is RPA

Single strands of DNA are held by replication protein A (RPA) to prevent them from joining back

10

What is the second step in replication

CDK (prolly 4 and 6) p's MCM, activating it

11

What happens next

RPA and MCM are the prereplicative complex. ORC goes away

12

Next

DNA Primase makes about 10 nts, pol alpha adds about another 30 nts, so now DNA e and t can come in and kick out the RNA nts and add DNA nts and bind them together by phosphodiester bonds.

13

What does the pol e and t need for their activity

PCNA which is a clamp (proliferating cell nuclear agent)

14

What direction is the DNA read and what direction is the DNA made

Always made 5' to 3' direction, read in 3' to 5'

15

What kind of coils are introduced by the replciative fork

positive super coils, topo induces negative super coils

16

How are Okazaki fragments formed

DNA pol e and t comes in, kickout the RNA nts, add in the DNA nts, but once they hit the next primer, there are now RNA nts which are kicked out by DNA pol t and e but they are removed by flipponuclease. This leaves nicks in the DNA synthesis on lagging strand. DNA ligase joins these nicks

17

How are histones removed

By chaperons

18

What removes histones ahead of the replication fork

Also chaperons

19

How does replication terminate

When two forks meet, telomeres shorten

20

How does germ line cells maintain their multipotency

They have enzymes called telomerase which keeps the length of the DNA the same

21

What are telomerases

They are reverse transcriptase enxymes

22

What is the cell division limit called? What is it?

Hayflick's limit, 50