DNA Replication

Question 1

Replication has to be

Answer 1

accurate and fast

Question 2

E. coli replication speed

Answer 2

1000 nucleotides/sec

Question 3

Conservative model of replication

Answer 3

Parent strands are retained whole

Question 4

Semi-conservative model of replication

Answer 4

Parent strands are paired with a complementary daughter strand

Question 5

Dispersive model of replicaton

Answer 5

Parent and daughter strands are inter-mixed

Question 6

How many bands of DNA would be expected after two rounds of conservative replication?

Answer 6

Two

Question 7

Replication origin

Answer 7

The place at which replication begins (one in prokaryotes, multiple in eukaryotes)

Question 8

Theta replication

Answer 8

circular DNA with single origin of replication that forms a replication fork and is bidirectional

Question 9

Rolling circle replication

Answer 9

single origin of replication - new DNA spools out of the original broken circle

Question 10

Eukaryotic replication

Answer 10

Linear replication with thousands of origins, replicons of 20,000-30,000 bp in length

Question 11

Leading strand

Answer 11

continuous replication

Question 12

Lagging strand

Answer 12

discontinuous replication - Okazaki fragments

Question 13

Direction of replication

Answer 13

5’ - 3’

Question 14

Initiator protein

Answer 14

Binds to origin and separates strands of DNA to initiate replication
Involved in: Initiation

Question 15

DNA helicase

Answer 15

Unwinds DNA at replication fork

Involved in: Unwinding

Question 16

Single strand binding proteins

Answer 16

Attach to single stranded DNA and prevents secondary structures from forming
Involved in: Unwinding

Question 17

DNA gyrase

Answer 17

Moves ahead of the replication fork, making and resealing breaks in the double helical DNA to release the torque that builds up as a result of unwinding at the replication fork
Involved in: Unwinding

Question 18

DNA primase

Answer 18

Synthesiszes a short RNA primer to provide a 3’ OH group for the attachment of DNA nucleotides
Involved in: Elongation

Question 19

DNA polymerase III

Answer 19

Elongates a nucleotide strand from the 3’ OH group for the attachment of DNA nucleotides
Involved in: Elongation

Question 20

DNA polymerase I

Answer 20

Removes RNA primers and replaces them with DNA

Involved in: Elongation

Question 21

DNA ligase

Answer 21

Joins Okazaki fragments by sealing nicks in the sugar phosphate backbone of newly synthesized DNA
Involved in: Termination

Question 22

Final error rate

Answer 22

1 in a billion

Question 23

Mistake rate of DNA 5’ to 3’ polymerase

Answer 23

1 in 10,000 - implies proofreading activities of other polymerases

Question 24

Autonomously replicating sequences

Answer 24

Similar to origins of replication in prokaryotes (only 100 nucleotides instead of 250)

Question 25

Replication Licensing Factor

Answer 25

Factor that switches on the replication fork after it has been created

Question 26

Telomere

Answer 26

End of the chromosome with a G-rich sequence

Question 27

Telomerase

Answer 27

Riboprotein complex that adds repeated sequences, creating the telomeric region