DNA Replication

Question 1

What is the semiconservative model of DNA replication?

Answer 1

The daughter DNA molecule will have one new strand and one strand from the parent DNA.

Question 2

What distinguishes prokaryotic DNA replication from eukaryotic?

Answer 2

Prokaryotes have a single origin of replication, while eukaryotes have multiple origins of replication.

Question 3

What enzyme opens and stabilizes DNA during replication?

Answer 3

Helicase.

Question 4

What does primase do in DNA replication?

Answer 4

Lays down RNA primer.

Question 5

What is the role of DNA polymerase 3?

Answer 5

Makes new DNA (5’ →3’) and extends the primers.

Question 6

What are Okazaki fragments?

Answer 6

Segments of DNA created on the lagging strand during replication.

Question 7

What is the function of DNA ligase?

Answer 7

Connects the Okazaki fragments to make a continuous strand.

Question 8

What is the purpose of proofreading enzymes in DNA repair?

Answer 8

Perform mismatch repairs.

Question 9

If an Adenine is matched with Guanine, the proofreading enzymes change the Guanine to a _______.

Answer 9

Thymine

Question 10

What is nucleotide excision repair?

Answer 10

A process where a nuclease cuts out wrong sections, and DNA polymerase fixes them.

Question 11

What are telomeres?

Answer 11

Non-coding segments at the ends of chromosomes that shorten with each replication.

Question 12

How are telomerases related to germ-line cells?

Answer 12

Telomerases lengthen the telomeres in germ-line cells (sperm, egg).

Question 13

What causes cancer at the cellular level?

Answer 13

Mutations during DNA replication lead to loss of control of the cell cycle.

Question 14

Does the P53 protein initiates apoptosis?

Answer 14

Yes

Question 15

What are the three main reasons cells divide?

Answer 15

1. Reproduce - unicellular organisms
2. Grow - multicellular development
3. Repair - replace old, dead, or worn-out cells.

Question 16

How many chromosomes do human somatic cells have?

Answer 16

46

Question 17

What are histones?

Answer 17

The protein that DNA is wrapped around - used as an organizer

Question 18

What are the parts of a nucleosome

Answer 18

DNA wrapped around proteins called histones.

Question 19

What is interphase?

Answer 19

The phase in between divisions where the cell is in normal functioning and preparation.

Question 20

What occurs during the S-phase of the cell cycle?

Answer 20

DNA replication - each piece of DNA is copied

Question 21

What holds sister chromatids together?

Answer 21

The centromere

Question 22

What is cytokinesis?

Answer 22

The process where the cell divides into two daughter cells

Question 23

What is the role of growth factors in the cell cycle?

Answer 23

They signal the cell to divide.

Question 24

What are CDK and cyclin in cell cycle regulation?

Answer 24

CDK is a constant protein kinase, while cyclin levels fluctuate during the cell cycle.

Question 25

What is MPF?

Answer 25

Maturation (mitosis) promoting factor that causes the cell to leave G2 and enter mitosis.

Question 26

At which checkpoint does the cell assess if spindle fibers are attached?

Answer 26

The M checkpoint during metaphase.

Question 27

What happens if a cell does not receive a go-ahead signal?

Answer 27

It exits the cycle and switches to a non-dividing state called the G0 phase.

Question 28

What is apoptosis?

Answer 28

Programmed cell suicide to protect the body if a cell gets stuck at a checkpoint.

Question 29

What occurs during the G2 Phase during Interphase?

Answer 29

The growth phase, where everything else doubles (enzymes, organelle, etc).