Basics for DNA Replication

Question 1

DNA helicase

Answer 1

separates DNA strands

powered by ATP hydrolysis

Question 2

single-strand DNA binding protein

Answer 2

prevents single stranded DNA from re-annealing

Question 3

topoisomerase

Answer 3

induces or relaxes supercoils by breaking 1 or both strands of DNA

Question 4

topoisomerase I

Answer 4

relaxes supercoils
breaks 1 DNA strand
does not require ATP

Question 5

topoisomerase II

Answer 5

relaxes or induces supercoils
breaks both DNA strands
does require ATP

Question 6

primer

Answer 6

a short stretch of RNA required for DNA synthesis

is made by primase

Question 7

replication fork

Answer 7

active site of DNA replication
moves in one direction
contains the leading and lagging strands

Question 8

leading strand

Answer 8

DNA strand of the replication fork that can be synthesized continuously

Question 9

lagging strand

Answer 9

DNA strand of the replication fork that is synthesized via Okazaki fragments

Question 10

DNA ligase

Answer 10

joins Okazaki fragments

requires ATP hydrolysis in eukaryotes; NAD+ hydrolysis in bacteria

Question 11

DNA polymerase III

Answer 11

synthesizes new DNA strands - the leading and lagging strand are made simultaneously
contains a core, sliding clamp, and clamp loader
is highly processive

Question 12

sliding clamp

Answer 12

binds DNA Pol III to bind, prevents it from dissociating

Question 13

clamp loader

Answer 13

loads the sliding clamp onto the DNA

involves ATP hydrolyzation

Question 14

telomere

Answer 14

the end of a chromosome

is longer in the leading strand

Question 15

telomerase

Answer 15

enzyme that extends the leading strand of the telomere
uses an RNA template to anneal to the leading strand
high activity could mean cancer activity