Unit #6: Cell Division

Question 1

What form of cell division occurs in prokaryotes?

Answer 1

Binary fission

Question 2

Where in a eukaryotic cell does binary fission occur.

Answer 2

Mitochondria and chloroplast.

Question 3

Why do cells divide?

Answer 3

Reproduction, growth and repair.

Question 4

Which type of cells do not divide and are permanently in the G0 stage?

Answer 4

Neurons and muscle cells.

Question 5

Which cells do not normally divide can be induced to into the cell cycle?

Answer 5

Liver cells, if they get damaged they will repair.

Question 6

Which cells are constantly dividing?

Answer 6

Skin cells, intestinal cells.

Question 7

What is a cell with one complete set of chromosomes called?

Answer 7

Haploid (n)

Question 8

What is a cell with two complete sets of chromosomes called?

Answer 8

Diploid (2n)

Question 9

In humans, which gametes are haploid?

Answer 9

Gametes

Question 10

What phase is the most time spent in in the cell cycle?

Answer 10

Interphase

Question 11

What three phases make up Interphase?

Answer 11

G1, S, G2

Question 12

What is the purpose of the G1 phase?

Answer 12

Growth and preparation for division

Question 13

What is the purpose of the S phase?

Answer 13

For DNA replication.

Question 14

What is the purpose of the G2 phase?

Answer 14

More growth, and development of microtubules.

Question 15

What model of replication does DNA use?

Answer 15

Semiconservative

Question 16

What does Chargaff’s law state?

Answer 16

Complimentary based exist in equal proportion.

Question 17

How many hydrogen bonds hold guanine and cytosine together?

Answer 17

3

Question 18

How many H bonds hold thymine and adenine together?

Answer 18

2

Question 19

What enzyme comes in and unzips the DNA molecule?

Answer 19

Helicase, while topoisomerase relieves pressure.

Question 20

What helps prevent re-annealing?

Answer 20

Single stranded binding proteins.

Question 21

What does RNA Primase do?

Answer 21

Lay down RNA primers that allow for nucleotides do be added in the 3’ direction.

Question 22

What is the purpose of DNA Polymerase III?

Answer 22

To add nucleotides on the 3’ end.

Question 23

What is the purpose of DNA Polymerase I?

Answer 23

Replaces the RNA primers with DNA

Question 24

What is the purpose of Ligase?

Answer 24

To seal loose ends between Okazaki fragments.

Question 25

Order the enzymes used in DNA Replication by order of appearance.

Answer 25

1. Helicase 2. Topoisomerase 3. RNA Primase 4. DNA Polymerase III 5. DNA Polymerase I 6. Ligase

Question 26

What are telomeres?

Answer 26

Short non-coding caps at the end of DNA strands to protect the genetic material.

Question 27

What occurs in Prophase?

Answer 27

Chromosomes condense, centrosomes move to poles of cell, mitotic spindle develops.

Question 28

What occurs in Prometaphase?

Answer 28

Nuclear envelope breakdown, nucleoli disappear, spindle fibers extend.

Question 29

What occurs in Metaphase?

Answer 29

Chromosomes line up on the metaphasic plate, spindle fibers attach (2 per chromosome)

Question 30

What occurs in Anaphase?

Answer 30

Spindle fibers shorten, chromosomes split apart

Question 31

What occurs in Telophase?

Answer 31

Nuclear membrane and nucleoli form, chromosomes uncondense, and karyokinesis occurs.

Question 32

What is karyokinesis?

Answer 32

The splitting of nuclei, which always occurs in cell division.

Question 33

What is cytokinesis?

Answer 33

The splitting of the plasma membrane. In plants, this includes splitting of the cell wall.

Question 34

Where is the G1 checkpoint and what are the requirements to pass it?

Answer 34

At the end of the G1 phase, determines if the cell continues to the S phase. Makes sure that the cell is large enough, has sufficient nutrients and undamaged DNA.

Question 35

Where is the G2 checkpoint and what are the requirements to pass it?

Answer 35

At the end of the G2 phase, successful DNA replication and undamaged DNA are required, and MPF.

Question 36

What is MPF.

Answer 36

Maturation promoting factor, occurs when cyclin binds to CDK in G2 and reaches peak activity in metaphase.

Question 37

How does MPF activity change throughout the cell cycle?

Answer 37

Starts in G2, rapidly increases until peak is reached in M phase, then rapidly decreases when G2 is reached.

Question 38

How does cyclin concentration change throughout the cell cycle?

Answer 38

Gradually increases until peak is reached in M phase, and then rapidly decreases.

Question 39

Where is the metaphase checkpoint and what are the requirements to pass it?

Answer 39

At the end of metaphase, spindle fibers must be attached to chromosomes to proceed to anaphase.