BIO 240 EXAM 2

Question 1

describe the 1st challenge of DNA replication

Answer 1

DNA poly III starts replication and it needs RNA primase to create complementary RNA strands to act as a landing zone on the template to initiate replication

Question 2

describe the 2nd challenge of DNA replication

Answer 2

DNA runs antiparallel, one strand moves continuously towards the replication fork creating the leading strand, while the other runs away from the replication fork which is the lagging strand. The lagging strand results in short segments that are called Okazaki fragments

Question 3

describe the 3rd challenge of DNA replication

Answer 3

helicase unwinds the double helix, which causes torsional tension which moves DNA towards the double helix. Topiomearase helps prevent this tensions which stops the DNA from tangling within itself

Question 4

what are the 5 challenges of DNA replication?

Answer 4

challenge 1: how does DNA polymerase get started
challenge 2: how are both strands replicated in the right direction
challenge 3: what keeps DNA from being tangled
challenge 4: how are linear ends replicated
challenge 5: How is the accuracy of replication ensured?

Question 5

describe the 4th challenge of DNA replication

Answer 5

RNA primer is used to start DNA replication
- gap is left at the end of the chromosome
- the single-stranded DNA at the end of the chromosome is degraded
- cell divides and loses more sequences

Question 6

describe the 5th challenge of DNA replication

Answer 6

Ensure the accuracy of DNA replication by using the DNA poly III, which has a quality control/proofreading activity that detects the wrong insertion of a base during replication ​