Topic 5

Question 1

DNA replication is…

Answer 1

semiconservative

Question 2

DNA polymerase

Answer 2

a group of multisubunit enzymes that catalyze synthesis of DNA

Question 3

most of our understanding of DNA replication comes from…

Answer 3

studies in prokaryotic cells

Question 4

properties of all DNA polymerases

Answer 4

1. synthesize DNA only in 5’ to 3’ direction (read in 3’ to 5’)
2. can add a new deoxyribonucleotide only to 3’ -OH

Question 5

replication fork

Answer 5

region of DNA synthesis where parental strands separate and two new daughter strands elongate; location of active DNA replication containing the replication macromolecular complex

Question 6

leading strand

Answer 6

synthesized in a continuous manner

Question 7

lagging strand

Answer 7

synthesized in a discontinuous manner in direction opposite of movement of replication fork

Question 8

Okazaki fragments

Answer 8

small pieces of newly synthesized DNA that are joined to form a new DNA strand in lagging strand

Question 9

primase

Answer 9

enzyme that synthesize Okazaki fragments (no 3’ OH required)

Question 10

exonuclease

Answer 10

enzyme activity that hydrolyzes (degrades) DNA or RNA from their ends

Question 11

RNAse H

Answer 11

exonuclease that degrades the RNA strand of RNA-DNA hybrids

Question 12

DNA ligase

Answer 12

enzyme that seals breaks in DNA strand

Question 13

There are _________ DNA polymerases with ___________.

Answer 13

different, similar functions

Question 14

clamp loading proteins

Answer 14

loads clamp proteins onto replication fork at primer

Question 15

sliding clamp proteins

Answer 15

load and hold polymerase onto template

Question 16

helicases

Answer 16

enzymes that catalyze the unwinding of parental DNA in ATP dependent manner

Question 17

single-stranded DNA-binding proteins

Answer 17

stabilize the unwound single-stranded template DNA

Question 18

topoisomerase

Answer 18

enzymes that catalyze the reversible breakage and rejoining of DNA strands to relieve torsion caused by unwinding of DNA

Question 19

The enzymes involved in DNA replication coordinate and synthesize both strands…..

Answer 19

simultaneously

Question 20

origins of replication (original)

Answer 20

serves as binding sites for the protein complex that initiates the replication process

Question 21

autonomously replicating sequence (ARS)

Answer 21

an origin of DNA replication in yeast

Question 22

origin recognition complex (ORC)

Answer 22

6 subunit complex that recruits other proteins (like helices) and recognizes core sequence and bind to it to initiate formation of replication bubble

Question 23

ori of eukaryotic chromosomes first studied in..

Answer 23

yeast

Question 24

telomerase

Answer 24

consists of (G-rich) repeats of simple-sequence DNA that is complementary to telomeric DNA (overhanging); also allows prokaryotic DNA to replicate as a linear molecule in yeast

Question 25

reverse transcriptase

Answer 25

a DNA polymerase that uses an RNA template

Question 26

Why is reverse transcriptase activity of telomerase necessary?

Answer 26

DNA polymerase cannot replicate the extreme 5' end

Question 27

As we age, telomeres....

Answer 27

become shorter

Question 28

The _______ of DNA replication is critical to cell reproduction. Usually....

Answer 28

accuracy, one in 10^9

Question 29

what is the rate of error frequency for simple hydrogen bonding of complementary base pairs during replication

Answer 29

1/100 to 1/1000 incorrect

Question 30

Active selection of correct base by polymerase based on conformation of the expected base accuracy

Answer 30

1/10^5 to 1/10^6 incorrect

Question 31

proofreading by polymerase accuracy

Answer 31

1/10^7 to 10^8 incorrect

Question 32

DNA repair mechanisms

Answer 32

increase fidelity and repair from damage like UV light and carcinogens

Question 33

proofreading

Answer 33

selective removal of mismatched bases by DNA polymerase

Question 34

primary function or telomeres

Answer 34

to protect chromosome ends from degradation

Question 35

telomerase activity can be detected from...

Answer 35

both lagging and leading strand