Biology Unit 3- chapter 15

Question 1

who created the experiments about what genes are made of?

Answer 1

Alfred Hersey and Barbara Chase

Question 2

what was the hypothesis of the experiments regarding genes?

Answer 2

DNA is genetic material that contains the information to be replicated.

Question 3

what are the details of the Hershey- Chase experiment?

Answer 3

viral DNA and viral protein were labeled with radioactive material, then spun in a centrifuge, DNA is in the pellet (heavier and falls). Protein is in the solution (not heavy). Identified DNA as were genes are located.

Question 4

how are phosphodiester bonds made?

Answer 4

condensation reactions

Question 5

what is the 5’ end of a deoxyribonucleotide?

Answer 5

phosphate group

Question 6

what is on the 3’ end of a deoxyribonucleotide?

Answer 6

carboxyl group

Question 7

what are the three parts of a deoxyribonucleotide?

Answer 7

sugar, nitrogenous base (A,T,G,C), and phosphate group

Question 8

semiconservative replication:

Answer 8

base pairs attach to make complimentary strand, one old one new for each

Question 9

conservative replication:

Answer 9

make fully new DNA strand copied form new DNA strand, one old strand one new

Question 10

dispersive replication:

Answer 10

sections of old are pulled apart and attached together with the new strand

Question 11

what was the experiment to test DNA replication?

Answer 11

Meselson- Stahl experiment

Question 12

explain the Meselson- Stahl experiment

Answer 12

Dna is grown with different isotopes of Nitrogen to see where they grow

Question 13

prediction of the semiconservative replication

Answer 13

2 Hybrid
2 14N

Question 14

prediction of the conservative replication

Answer 14

1 15N
3 14N

Question 15

prediction of the dispersion replication

Answer 15

4 hybrid

Question 16

what is the correct model for DNA replication

Answer 16

semi-conservative replication model

Question 17

how does DNA replicate (direction and from where)

Answer 17

two directions from each origin of replication

Question 18

bacterial chromosome DNA replication:

Answer 18

single origin of replication, circle

Question 19

eukaryotic chromosome DNA replication:

Answer 19

multiple origins of replication, line

Question 20

replication occurs in which direction on which strand

Answer 20

5’ to 3’ on daughter strand

Question 21

DNA polymerase reads in which direction on which strand

Answer 21

3’ to 5’ on parental strand

Question 22

where are new nucleotides added?

Answer 22

3’ hydroxyl group on the last nucleotide on the strand

Question 23

helicase:

Answer 23

catalyzes the breaking of hydrogen bonds between base pairs to open the double helix

Question 24

single-strand DNA-binding proteins (SSBPs)

Answer 24

stabilizes single-stranded DNA

Question 25

Topoisomerase

Answer 25

Breaks and rejoins the DNA double helix to relieve twisting forces caused by the opening of the helix

Question 26

primase

Answer 26

catalyzes the synthesis of the RNA primer, creates short RNA primer to provide 3’ hydroxyl a place where new DNA can be added

Question 27

DNA polymerase III

Answer 27

extends the leading strand

Question 28

sliding clamp

Answer 28

holds DNA polymerase during strand extension

Question 29

which way is the leading strand synthesized?

Answer 29

5’ to 3’

Question 30

which way is the lagging strand synthesized?

Answer 30

3’ to 5’

Question 31

which strand is moving in the same direction as the DNA polymerase and helicase?

Answer 31

the leading strand

Question 32

DNA ligase

Answer 32

catalyzes the joining of Okazaki fragments into a continuous strand

Question 33

what is it called when all of the synthesis is happening simultaneously

Answer 33

replisome

Question 34

how many forks does each replication bubble have?

Answer 34

two

Question 35

telomerase:

Answer 35

fixes open end of DNA chromosome by adding RNA template

Question 36

telomeres:

Answer 36

end of the DNA strand with no DNA nucleotides

Question 37

proofreading:

Answer 37

DNA polymerase adds a mismatched nucleotide then sees mistake and fixes it

Question 38

nucleotide excision:

Answer 38

thymine dimer- cuts the damaged bases out and adds in new ones

Question 39

During DNA replication, DNA polymerase “reads” the template strand in the _______ direction.
A. 5’ to 3’.
B. It depends on whether the new strand that is being made off that template is the leading or lagging strand.
C. 5’ to 5’.
D. 3’ to 3’.
E. 3’ to 5’.

Answer 39

3’ to 5’

Question 40

Consider the replication bubble below. The red strands are the newly-made DNA, grey is the template. Where are the lagging strands being made?

A. The new strands in areas A and C are lagging strands.
B. The new strands in areas A and D are lagging strands.
C. The new strands in areas B and D are lagging strands.
D. The new strands in areas B and C a lagging strands.

Answer 40

A. The new strands in areas A and C are lagging strands.

Question 40

During DNA replication, DNA polymerase __________ while DNA helicase ___________.
A. Stabilizes single-stranded DNA; relieves twisting forces.
B. Creates new hydrogen bonds between nucleotides; breaks the hydrogen bonds between the template strands.
C. Makes the last phosphodiester bond between two new DNA segments; creates a primer.
D. Prevents separated strands from re-annealing; relieves twisting forces.

Answer 40

B. Creates new hydrogen bonds between nucleotides; breaks the hydrogen bonds between the template strands.

Question 41

Why is telomerase necessary?
A. Because DNA polymerase usually falls off the template before it reaches the end of a chromosome, and so leading strand synthesis is incomplete.
B. Because primase cannot bind at the very end of a DNA molecule, and so leading strand synthesis comes up a bit short.
C. Because DNA polymerase usually falls off the template before it reaches the end of a chromosome, and so lagging strand synthesis is incomplete.
D. Because primase cannot bind at the very end of a DNA molecule, and so lagging strand synthesis comes up a bit short.

Answer 41

D. Because primase cannot bind at the very end of a DNA molecule, and so lagging strand synthesis comes up a bit short.

Question 42

What does “proofreading” refer to in the context of DNA replication?
A. Telomerase binding to specific sequences of DNA.
B. Ligase stitching together different Okazaki fragments.
C. DNA polymerase III recognizing bends in the sugar phosphate backbone caused by mismatches and removing those bases.
D. DNA polymerase I removing RNA primers from Okazaki fragments.

Answer 42

C. DNA polymerase III recognizing bends in the sugar phosphate backbone caused by mismatches and removing those bases.

Question 43

Consider the four steps below for DNA replication of a lagging strand. Which one is second in chronological order?
1. DNA ligase closes gap in the sugar-phosphate backbone.
2. primase binds to the area newly opened and creates an RNA primer.
3. DNA polymerase III binds to the template strand and synthesizes DNA.
4. DNA polymerase I removes RNA primer and replaces it with DNA.

Answer 43

3. DNA polymerase III binds to the template strand and synthesizes DNA.

Question 44

which of the following is a RNA-dependent DNA polymerase?
1. DNA polymerase I
2. helicase
3. primase
4. telomerase

Answer 44

telomerase

Question 45

which of the following experimental results would have convinced Meselson and Stahl to support the dispersive model of DNA replication and eliminate the other possible models?
1. only one DNA band in the centrifuge tube for the first generation.
2. only one DNA band in the centrifuge tube for the second generation.
3. two distinct DNA band in the centrifuge tube for the first generation.
4. two distinct DNA band in the centrifuge tube for the second generation.

Answer 45

2. only one DNA band in the centrifuge tube for the second generation.