chapter 12

Question 1

Imagine that a doctor is culturing cells from a malignant melanoma and from a normal skin sample. How would you expect these two cell populations to differ?

Answer 1

Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres.

Question 2

What is the function of the enzyme DNA polymerase?

Answer 2

to synthesize a strand of DNA using DNA as a template

Question 3

Which of the following statements is not true regarding chromosome replication?

Answer 3

• During chromosome replication, multiple origins of replication form for all DNA in a cell.
• Replication bubbles remain distinct, isolated structures during chromosome replication and never fuse with one another.
• In humans, it takes several days to replicate an entire chromosome.
• During chromosome replication, only linear DNA within eukaryotic cells is copied.

Question 4

Mitochondria contain their own DNA and replicate on their own. Why don’t they suffer the same consequences as our cells in terms of limited division?

Answer 4

Mitochondrial DNA is circular, so it doesn’t shorten when it replicates.

Question 5

What is the name of the class of enzymes that recognizes a specific sequence of DNA and cuts it?

Answer 5

restriction enzymes

Question 6

_______ requires both a template and an appropriately placed DNA 3’ end to synthesize a nucleic acid.

Answer 6

DNA polymerase

Question 7

Which of the following reasons explains why bacteria can continually divide?

Answer 7

because their DNA is circular so the DNA never shortens after replication

Question 8

_______ moves outward from the origin of replication and breaks hydrogen bonds between DNA nucleotides.

Answer 8

Helicase

Question 9

What is the benefit of using Taq polymerase in PCR?

Answer 9

Because it is taken from bacteria that lives in high temperatures, it does not denature and more DNA polymerase does not have to be added after every cycle.

Question 10

________ is the first enzyme to synthesize a nucleic acid at a replication fork.

Answer 10

RNA primase

Question 11

Which of the following statements are true regarding telomeres?

Answer 11

Telomeres can contain repeated base sequences

Question 12

Which of the following statements about the strands of a newly replicated DNA molecule is correct?

Answer 12

One strand is new and the other is from the original molecule

Question 13

DNA sequencing using the Sanger method relies on

Answer 13

the termination of DNA synthesis at specific bases

Question 14

Why are single-stranded binding proteins necessary for DNA replication?

Answer 14

They prevent the two parental strands from coming together again.

Question 15

Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come?

Answer 15

the incoming nucleotide

Question 16

A Southern blot is a technique that relies on

Answer 16

hybridization of DNA sequences to complementary DNA sequences

Question 17

During PCR, where does the energy come from that adds the nucleotide to the growing DNA strand?

Answer 17

the incoming nucleotides

Question 18

The first step of PCR is called annealing

Answer 18

false (denaturation)

Question 19

During DNA replication, the leading strand contains Okazaki fragments.

Answer 19

false : lagging strand contains okazaki

Question 20

RNA is involved in which of the following cellular processes?

Answer 20

DNA replication, transcription, and translation

Question 21

What procedure is typically used after PCR is complete to make sure the amplification process worked properly

Answer 21

gel electrophoresis

Question 22

The following enzymes play important roles in DNA replication:

DNA polymerase
Primase
Ligase
Helicase

In what order do they work during replication?

Answer 22

Helicase, primase, DNA polymerase, ligase

Question 23

_________ relieves the tension on the double helix during DNA replication.

Answer 23

Topoisomerase