ALL THE THINGS

Question 1

DNA replication is described by what model?

Answer 1

Semiconservative Model

Question 2

What do DNA polymerases do?

Answer 2

read DNA templates (parent strands) in the 3’-5’ direction

Synthesized a complementary DNA strand in the 5’-3’ direction

Question 3

The Replication Fork is made of what two strands?

Answer 3

Leading and Lagging strand

Question 4

What direction is the leading strand synthesized?

Answer 4

5’-3’ in the same direction as the rep fork

Question 5

What direction is the lagging strand synthesized?

Answer 5

5’-3’ in the opposite direction of the replication fork

Question 6

Can the lagging strand be synthesized continuously?

Answer 6

NO! synthesized as small fragments called Okazaki fragments which are later ligated

Question 7

DNA replication can only begin at what specific sequences?

Answer 7

Origins of replication

Question 8

How many replication forks begin from ever origin?

Answer 8

2 in opposite directions

Question 9

DNA polymerases require an existing what?

Answer 9

3’-OH to add nucleotides to

provided by a Primer; cant synthesize using a naked strand

Question 10

What is primase?

Answer 10

DNA-dependent RNA polymerase

Question 11

What does primase do?

Answer 11

synthesizes a short RNA primer complementary to the template strand; provide the necessary 3’OH; do not require primers

Question 12

What are the substrates for DNA chain elongation?

Answer 12

deoxynucleotidetriphosphates (dNTPs)

Question 13

What is the reaction mechanism for DNA chain elongation?

Answer 13

nucleophilic attack by 3’-OH of primer on first phosphate (alpha) of the incoming dNTP

Is a transesterification rxn

Question 14

What happens to the other 2 phosphates in DNA chain elongation?

Answer 14

released as inorganic phosphate (PPi)

Question 15

Is the DNA chain elongation reaction reversible?

Answer 15

NO! irreversible

Question 16

Most enzymes are what?

Answer 16

distributive; dissociate from substrate and product after catalyzing their reaction

Question 17

What is processivity?

Answer 17

ability of an ezyme to catalyze multiple reactions without releasing its substrate

Question 18

For DNA polymerases, processivity is what?

Answer 18

the number of nucleotides added before the polymerase dissociates

Question 19

DNA Poly III has what kind of processivity?

Answer 19

High

Question 20

DNA Poly I has what kind of processivity?

Answer 20

Low

Question 21

What do highly processive DNA polys use to remain associated with their templates?

Answer 21

sliding clamps loaded via ATP hydrolysis

Question 22

DNA Polys make a mistake every —

Answer 22

10,000 — 100,000

Question 23

What does proofreading do?

Answer 23

removes incorrect, mispaired nucleotides introduced by errors

Question 24

What kind of activity do proofreaders show?

Answer 24

3’-5’ exoneclease activty in most but not all DNA polys