Session 5 extras

Question 1

What is the end replication problem?

Answer 1

Refers to how the final Okozaki fragment on the lagging strand isn’t complete

Question 2

Why does the end replication problem occur?

Answer 2

RNA primer added for final Okozaki fragment

but when it’s removed, DNA polymerase cannot fill in that gap since it can’t add nucleotides to the 5’ end

Question 3

What effect does the end replication problem have on the length of DNA produced?

Answer 3

Shortens with each round of replication

Question 4

How can the end replication problem be overcome?

Answer 4

Telomerase enzyme forms telomeres at ends of DNA

overcomes shortening

Question 5

What inheritance pattern does xeroderma pigmentosa show?

Answer 5

Autosomal recessive

Question 6

What is the cause of xeroderma pigmentosa?

Answer 6

Mutations in gene conding for enzyme

defective nucleotide excision repair enzyme

Question 7

What are patients with xeroderma pigmentosa most sensitive to? Why?

Answer 7

Sunlight
because it contains UV light
which causes DNA damage that’s usually repaired by nucleotide excision repair