1. DNA REPLICATION

Question 1

Can proteins recognize the base sequence of DNA without unwinding it?

Answer 1

Yes ex. restriction enzyme

Question 2

What is DNA replication

Answer 2

Process of duplication of the entire genome prior to replication

Question 3

What phase of the cell cycle does replication occur

Answer 3

S phase

Question 4

What are the steps involved in DNA replication

Answer 4

Initiation, Elongation and Termination

Question 5

Basic rules of replication

Answer 5

Semi-conservative
starts at the 'origin' 
can be uni or bi directional 
semi-discontinuous 
Synthesis always in the 5-3' direction 
RNA primers required

Question 6

What bases are broken during origin of DNA replication

Answer 6

A-T base pairs because it is easier to break 2 H-bonds than 3

Question 7

Another name for leading strand template

Answer 7

left hand fork

Question 8

Another name for lagging strand template

Answer 8

right hand fork

Question 9

what enzyme does the bidirectional synthesis of the DNA double helix

Answer 9

DNA Polymerase

Question 10

what enzyme corrects mistaken base pairings and proof reads?

Answer 10

DNA polymerase

Question 11

what happens if a base mismatch occurs?

Answer 11

DNA polymerase has 3’➡️5’ exonuclease activity in order to forrest errors

Question 12

Where does energy for addition of nucleotide come from

Answer 12

From cleavage of high energy phosphate of incoming triphosphate

Question 13

Why does Dna replication have to occur in the 5’ to 3’ direction

Answer 13

reaction doen not proceed, as no high energy bond will be cleaved

Question 14

Topoisomerase

Answer 14

Prevents torsion by DNA breaks

Question 15

Helicases

Answer 15

separates 2 strands (open double helix and held it unwind)

Question 16

Primase

Answer 16

RNA primer synthesis

Question 17

Single strand binding proteins

Answer 17

prevent reannealing of single strands (keeps strands separated)

Question 18

DNA polymerase

Answer 18

synthesis of new strand

Question 19

Tethering protein

Answer 19

stabilises polymerase

Question 20

DNA ligase

Answer 20

seals nick via phoshodiester linkage

Question 21

Okazaki fragments

Answer 21

small fragment of new DNA

Question 22

Nuclease

Answer 22

removes the RNA primer nucleotide by nucleotide

Question 23

Repair polymerase

Answer 23

replaces RNA with DNA

Question 24

DNA ligase

Answer 24

seals the sugar-phophate backbone by creating phophodiester bond (requires Mg2+ and ATP)

Question 25

what is the sequence in which the proteins function during DNA replication

Answer 25

1- Topoisomerase 
2-DNA helicase 
3-RNA primase 
4-DNA polymerase 
5-Tethering proteins 
6-DNA ligase