Cell division and cell cycle

Question 1

Describe interphase

Answer 1

Duplication of decondensed chromosomes

Question 2

Describe prophase

Answer 2

Two centrosomes appear

Chromosomes condense to 2 sister chromatids

Kinetochores form

Mitotic spindles form

Question 3

Describe prometaphase

Answer 3

Chromosomes move in active motion

Fragments of nuclear envelope are present

Kinetochore microtubules are formed

Question 4

Describe metaphase

Answer 4

2 spindle poles are present

Chromosomes line up in a mid-line plane between the 2 poles

Question 5

Describe anaphase

Answer 5

Kinetochore shortens

spindle poles move outward

daughter chromosomes separate between the 2 poles

Question 6

Describe telophase

Answer 6

Daughter chromosomes are present at spindle poles

contractile ring forms in center

Nuclear envelope reassembles around each daughter chromosome bundle

Question 7

How long does telophase take?

Answer 7

~5 hours

Question 8

Describe cytokinesis

Answer 8

Completed nuclear envelope surrounds deconsensing chromosomes

Contractile ring creates deep cleavage furrow

Reformation of interphase microtubules and centosome

Question 9

What are permanent cells?

Answer 9

Cells that exit the cell cycle and cannot come back.

Non-renewable

Question 10

What are stable cells?

Answer 10

Cells that exit the cell cycle but may come back if necessary

Question 11

Where would stable cells enter the cell cycle?

Answer 11

G0

Question 12

What is G1 of the cell cycle?

Answer 12

Growing phase (Interphase)

Question 13

What is S of the cell cycle?

Answer 13

DNA synthesis phase (Interphase)

Question 14

What is G2 of the cell cycle?

Answer 14

Growing phase (Interphase)

Question 15

What is M of the cell cycle?

Answer 15

Nuclear and cellular division (Mitosis)

Question 16

What is an example of a permanenet cell? Stable cell?

Answer 16

Hair cells in ear
Nerve cells

Parenchymal cells in liver
Smooth muscle cells

Question 17

Cells that continuously divide are called what kind of cells?

Answer 17

Labile cells

Question 18

Name 2 examples of labile cells

Answer 18

Epithelium, hematopoietic cells

Question 19

What is the big problem with the proliferative potential of stem cells?

Answer 19

Getting stem cells to differentiate the right amount in the right place (and not cause cancer)

Question 20

How do epithelium cells of the GI tract differentiate?

Answer 20

Epithelial cells differentiate from stem cells and migrate to the top of the villi

The are shed from the villi in ~5 days

Question 21

Inhibition of what arachidonic acid derivative will induce loss of gut integrity?

Answer 21

COX-1

Question 22

Is it common for cells to need more than one growth signal to initiate growth?

Answer 22

Yes

Question 23

Can hormones act as growth factors? If yes, name 3 of them

Answer 23

Yes

Estrogen
Testosterone
Norepinephrine (exercise)

Question 24

What are the check points of the cell cycle?

Answer 24

G1/S check point
G2/M check point
M check point

Question 25

What is does the G1/S check point ensure?

Answer 25

Appropriate growth signal Cell size Environment DNA

Question 26

If there was no G1/S check point and a reduction in nutrition, what would happen to cell division?

Answer 26

Cells shrunken from malnutrition would divide

Question 27

What does the G2/M check point ensure?

Answer 27

DNA duplication after S phase is okay | Cell size

Question 28

What does the M check point ensure?

Answer 28

Chromosomes are correctly distributed

Question 29

Describe the check points necessary for Cyclin-dependent-kinase activity

Answer 29

Has specific phosphate been removed? Has specific phosphate been added? Is cyclin present? If yes, then output

Question 30

Describe the Cyclin D G1/S check point pathway

Answer 30

pRB holds transcription factors inactive Growth signals cause transcriptions of cyclins* A,B,D Cyclin-dependent kinase forms complex with cyclin D* CDK-cD complex phosphorylates pRB Phosphorylation of pRB releases transcription factors Transcription factors induce transcription of proteins necessary for chromosome duplication (S phase)

Question 31

What is pRB? What cancer is it associated with?

Answer 31

retinoblastoma protein Eye tumors

Question 32

When are concentrations of cyclin and CDK-cyclin complex at their highest?

Answer 32

During mitosis

Question 33

Describe the pathway that blocks cyclin D at the G1/S check point

Answer 33

Cell senses injury Cell transcribes p53 p53 inhibits cell cycles and instead induces transcription of repair enzymes

Question 34

How does p53 inhibit cell cycle?

Answer 34

p53 inhibits the growth signals that activate the cyclin D-cyclin-dependent-kinase complex

Question 35

Is p53 inhibition of the cell cycle permanent?

Answer 35

No, only until the cell is repaired