DNA replication - lecture 2

Question 1

What did Arthur Kornberg discover and when?

Answer 1

1959 - discovering the mechanism for biological synthesis of DNA

Question 2

What is the difference between eukaryote and prokaryote replication?

Answer 2

Eukaryote - multiple site of origin, speeds up replication slightly
Prokaryote - one site of replication

Question 3

Does DNA replicate uni or bi-directionally?

Answer 3

DNA synthesis can occur both uni- directionally and bi - directionally.
To replicate bi- directionally , a replication fork must occur .

Question 4

How does the leading strand replicate?

Answer 4

Continuously , in 5’ to 3’ direction

Question 5

How does the lagging strand replicate?

Answer 5

Discontinuously. Still 5’ to 3’ .

RNA primate adds an RNA primer to start synthesis.
Polymerase can add Okazaki fragments , after the RNA is added. DNA polymerase 3 lays down new DNA.
Finally DNA ligase joins the fragments together.

Question 6

What does dNTP stand for? what does it do?

Answer 6

deoxynucleotide triphosphate. This is the substrate used to extend the DNA sequence .

Question 7

What type of nucleic acid are the primers?

Answer 7

RNA primers

Question 8

What are the 6 common rules of DNA replication?

Answer 8

• Semi - conservatief
• Starts at ‘ori’
• Can be uni or bidirectional
• Semi - discontinuous
• synthesis 5’ to 3’
• RNA primers required

Question 9

Topoisomerases

Answer 9

prevents torsion by DNA breaks

Question 10

Singel strand binding proteins

Answer 10

prevent reannealing of single strands

Question 11

Tethering proteins

Answer 11

stabilises DNA polymerase

Question 12

Primase

Answer 12

RNA primer synthesis

Question 13

What are the different polymerase in replication

Answer 13

polymerase 3 - connects the Okazaki fragments

polymerase 1 - turns the RNA primers into DNA