Module 6 DNA Replication: 3/31

Question 1

DNA Replication Step 1

Answer 1

At origin sites, DNA STRANDS SEPARATE, forming a replication “bubble” with replication forks at each end
* Replication proceeds in both directions

Question 2

DNA Replication Step 2

Answer 2

HELICASE UNWINDS DNA helix while single-strand binding proteins hold the strands apart

Question 3

Replication Step 3

Answer 3

DNA POLYMERASE CATALYZE the elongation of new DNA at a replication fork
* Needs available 3’-OH, which is synthesized by primase

Question 4

Step 4

Answer 4

DNA NUCLEOTIDES are then added to the primer, building new strand and base-pairing with the template in the 5’-3’ direction
* Different polymerase later replaces the primer
* Rate of elongation is about 500 nucleotides/sec in bacteria
and 50/sec in human cells

Question 5

IMPORTANT***

ON EXAM: DRAW PROCESS OF DNA REPLICATION FROM MODULE 6