DNA Structure

Question 1

How many hydrogen bonds does A - T have

Answer 1

2

Question 2

How many hydrogen bonds does G - C

Answer 2

3

Question 3

DNA Helicase

Answer 3

unwinds the DNA strands, producing a Y-shaped replication fork

Question 4

Topoisomerase

Answer 4

Cuts and rejoins DNA to prevent twisting in circular bacterial chromosomes

Question 5

What keeps the opened DNA strands from reforming?

Answer 5

Single Stranded Binding Proteins

Question 6

DNA replications happens in what direction? Meaning what direction are the parental helixes and what direction is DNA synthesized?

Answer 6

DNA replication happens: 5 to 3

The parental leading strand is 3 to 5 and the lagging is 5 to 3

Question 7

Semi Conservative Replication

Answer 7

Each new strand of DNA has an old strand of DNA

Question 8

What is at the end of each 3’?

Answer 8

Hydroxl Group

Question 9

Ligase

Answer 9

Restitches DNA after it had been cut by topoisomerase

Question 10

What does the Primase Enzyme do?

Answer 10

Lays down RNA primers

Question 11

What does primase need in order to synthesize the RNA primer?

Answer 11

Hydroxl group on the 3’ end

Question 12

In what direction does Primer lay down the RNA?

Answer 12

5’ to 3’

Question 13

Primase and Polymerase read the strand?

Answer 13

3 to 5

Question 14

What does Polymerase need to synthesize?

Answer 14

The hydroxl group on the 3’ end

Question 15

Leading strand

Answer 15

only needs one primer to go continuously

Question 16

Lagging strand

Answer 16

Has multiple Sequences of both Primer and DNA

Question 17

Okazaki Fragments

Answer 17

These are the multiple strands of DNA that are left after DNA polymerase type 1 gets rid of the primer

Question 18

What gets rid of the RNA primers?

Answer 18

DNA polymerase type 1

Question 19

DNA polymerase needs what in order to synthsize?

Answer 19

the OH group

Question 20

DNA Ligase

Answer 20

reattach the strands after DNA polymerase type 1 has synthesized the new DNA strands after getting rid of the primers.

Question 20

Difference between DNA polymerase Type 1 and 3

Answer 20

Type 1 takes off the primers and then synthesizes

Type 3 builds off of the primer RNA strand and synthesizes

Question 21

Conservative replication model

Answer 21

The old DNA strands are used as a template for the new DNA be made, however the old DNA rewind back together

Question 22

Dispersive replication model

Answer 22

each pair of DNA has pieces of the old and the new when it is replicated

Question 23

Sliding DNA clamp

Answer 23

attaches to the end of the DNA polymerase and increases rate of synthesis

Question 24

Place when DNA replication starts

Answer 24

Origin of Replication (ori)

Question 25

Ligase

Answer 25

After DNA Polymerase type 3 synthesizes along the Okazaki fragments, Ligase rejoins the strands

Question 26

Why does the chromosome shorten?

Answer 26

Because once the primer is removed, there is only a 5' left and without that OH group, it shortens with each replication

Question 27

Telomere

Answer 27

At the ends of each chromosome that have noncoding DNA

Question 28

Telomerase

Answer 28

Expresses complementary nucleotides at the end of the 5' that is on the Telomer Active only in rapidly dividing embryonic cells, in germ cells – and in cancerous somatic cells

Question 29

Proofreading mechanism

Answer 29

allows DNA polymerases to back up and remove mispaired nucleotides using 3′→5′ exonuclease activity to remove the newly added incorrect nucleotide

Question 30

Base-excision repair

Answer 30

removing the erroneous base and replacing it with the correct one based on complementary pairing rules

Question 31

Nucleotide-excision repair

Answer 31

removing an entire segment of DNA to repair bulky distortions