DNA Replication

Question 1

What is a replication bubble and replication fork?

Answer 1

bubble - a region of DNA where the double helix is unwound and separated to allow the replication process to occur
fork - is the Y-shaped structure that forms within a replication bubble as the DNA strands unwound

Question 1

What is an ORI Sequence?

Answer 1

origin of replication; euk. multiple, pro. - have one

Question 2

Explain how replication is bidirectional and discontinuous.

Answer 2

synthesis occurs simultaneously in both directions away from the origin
one of the strands (leading strand) synthesized continuously in the 5’ to 3’ direction, following the opening of the replication fork
lagging strand is synthesized in a series of short fragments (okazaki fragments), due to the antiparallel nature of DNA

Question 3

What does helicase do?

Answer 3

separates (unzip) the strands

Question 4

What does the protein SSB do?

Answer 4

keep the strand single

Question 5

What does topoisomerase do?

Answer 5

the reliever for the strain caused by unwinding

Question 6

what does the primase does and what does it set up?

Answer 6

makes RNA primers complementary to the DNA parent
sets up DNA poly III (bacteria) and does so by adding complementary bases to 3’ end; hence keeps the contingent of 5’ to 3’ direction

Question 7

What does the DNA ligase do?

Answer 7

works by joining new and old DNA from the fragments with phosphodiester bonds (the glue)

Question 8

What does DNA polymerase 1 do?

Answer 8

removes the RNA and replaces it with DNA nucleotides