Cell Cycle and Mitosis

Question 1

G1 Phase

Answer 1

Gap 1: Cell growth and normal metabolism

Question 2

S Phase

Answer 2

Synthesis: Replication of chromosome, 12 hours

Question 3

G2 Phase

Answer 3

Gap 2: Growth and Preparation for cell division

Question 4

M Phase

Answer 4

Mitotic Phase: Mitosis and Cytokinesis

Question 5

G0 Phase

Answer 5

Resting phase - Not doing nothing, just not dividing

Question 6

Total Time for the Cell Cycle

Answer 6

15-24 hours total for eukaryotes, 20-30 minutes for bacteria

Question 7

Mitosis produces:

Answer 7

Identical daughter cells

Question 8

G2 of Interphase

2

Answer 8

1. Chromosomes have duplicated

2. Two centrosomes formed in preparation for making the mitotic spindle

Question 9

Prophase

2

Answer 9

1. Chromosomes have condensed

2. The mitotic spindle forms

Question 10

Spindle

2

Answer 10

1. Spindle is a combo of centrosomes and the microtubules growing out of them
2. Move chromosomes around and elongate the cell

Question 11

Prometaphase

2

Answer 11

1. Fragmentation (ripping apart) of the nuclear envelope

2. Microtubules attach to the newly formed kinetochore

Question 12

Kinetochore

Answer 12

Binding site on chromosome pair

Protein attachment points on chromosomes for mictrotubules

Question 13

Metaphase

3

Answer 13

1. Chromosomes align at metaphase plate
2. Centrosomes at opposite end of the cell
3. Each pole wants chromsome, so it jostles them until they end up at the metaphase plate

Question 14

Anaphase

3

Answer 14

1. Separation of sister chromatids
2. Cell elongates
3. Cohesin degrades

Question 15

Cohesin

Answer 15

Protein which binds sister chromatids together

Question 16

Telophase

2

Answer 16

1. Nuclear envelope on daughter nuclei reforms

2. Cytokinesis soon follows

Question 17

Kinetochore mictrotubules

Answer 17

Chromatids move along these to the opposite end of the cell

Question 18

Non-kinetochore mictrotubules

Answer 18

These overlap and allow motor proteins to walk along the opposite microtubule, ELONGATING the cell (region of overlap is reduced)

Question 19

Cytokinesis

4

Answer 19

1. Dividing up the cell contents
2. Contractile ring forms at metaphase plate
3. Ring contracts
4. Cleavage furrow forms

Question 20

What is the contractile ring made up of?

Answer 20

Microfilaments (actin) and the motor protein myosin

Question 21

What causes the contractile ring to contract?

Answer 21

Myosin walks along the microfilaments

Question 22

What does the G1 checkpoint check for?

3

Answer 22

Cell big enough?
Enough nutrients?
DNA damage?

Question 23

What does the G2 checkpoint check for?

3

Answer 23

DNA replication completed?
DNA damage?
Cell large enough?

Question 24

M checkpoint known as?

Answer 24

Spindle checkpoint

Question 25

What does the cell do if the cell does not pass the checkpoint

Answer 25

1. Arrest cell division
2. Allow time to repair problem
   Fixed? Resume! Not fixed? Apoptosis

Question 26

What regulates the cell cycle?

Answer 26

Cyclins and CDKs

Question 27

CDKs:
Present when?
Concentration?
Activated by WHAT?

Answer 27

Present throughout the whole cell cycle
Concentration doesn’t change throughout, BUT activity/purpose does
Activity depends on cyclins
Activated by the binding of a cyclin

Question 28

Cyclin

Answer 28

Regulatory protein that binds CDK

Cyclin concentrations change depending on the stage of the cell cycle

Question 29

MPF

Answer 29

Mitosis promoting factor
Active CDK binding with cyclin
M checkpoint-MPF activity

Question 30

P53
What?
Does what?
Example

Answer 30

A transcription factor - AKA: Tumor Suppressor
Works under damaged cell conditions: becomes activated and shuts down the cell cycle OR promotes apoptosis
Ex: DBL stranded DNA break bc of x-ray/ gamma ray

Question 31

P53 inhibits passage from ____ to ____ following DNA damage

WHY/HOW

Answer 31

G1 to S

P53 transcribes a protein (P21) that blocks cyclin accumulation