W3 DNA replication

Question 1

where do chromosomes replicate from

Answer 1

origin of replication

Question 2

what makes a region an origin of replication

Answer 2

high amounts of A and T

Question 3

which direction does the replication fork go

Answer 3

5’ to 3’

Question 4

which strand is in the 5’ to 3’ direction

Answer 4

leading strand

Question 5

what are lagging strand fragments called

Answer 5

okazaki strands

Question 6

how is supercoiling undone

Answer 6

by topoisomerase

Question 7

why must RNA primers be removed off okazaki fragments

Answer 7

so there are no RNA left

Question 8

when a flap is made on the okazaki fragment how is it removed

Answer 8

by FEN1

Question 9

how is the RNA primer degraded

Answer 9

ribonuclease H

Question 10

how does circular chromosome replicate

Answer 10

• initiator proteins start at origin of replication
• helix is opened and then helicase binds
• loading proteins detach

Question 11

why cant we fully replicate lagging strand

Answer 11

no upstream RNA primer

Question 12

what is the telomere and its function

Answer 12

repeating nucleotides which can loop to prevent unwanted DNA repair

Question 13

whats the role of the PCNA complex

Answer 13

improve speed of DNA replication

Question 14

what chemical process activates DNA replication in the S phase

Answer 14

phosphorylation

Question 15

what happens to histones during replication

Answer 15

recycled in the s phase

Question 16

Name the 5 proteins at the replication fork

Answer 16

helicase
SSBPs
DNA polymerase
RNA primers
ligase

Question 17

why do cells need a replication limit

Answer 17

• less mutations
• no loss of DNA

Question 18

what can stain DNA

Answer 18

ethidium bromide and UV light

Question 19

how can PCR measure gene expression

Answer 19

measure the amount of cDNA reverse transcribed

Question 20

what are the main roles of Pol-α + Pol-δ + and Pol-ε

Answer 20

Pol-α synthesises primers
Pol-δ works on the lagging strand
Pol-ε synthesises the leading strand

Question 21

what are the steps for PCR

Answer 21

heat to 95 to remove H bonds
cool to 50 to anneal primers
heat to 72 for taq polymerase to extend

Question 22

why might active telomerase be harmful

Answer 22

Can lead to cancer

Question 23

what is needed for electrophoresis

Answer 23

TAE buffer
agarose gel

Question 24

how is recombinant DNA created

Answer 24

cut plasmids with restriction enzymes
ligate sticky ends

Question 25

What does qPCR measure

Answer 25

Gene expression levels based on UV