Cell division and cell cycle Flashcards

1
Q

Describe interphase

A

Duplication of decondensed chromosomes

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2
Q

Describe prophase

A

Two centrosomes appear

Chromosomes condense to 2 sister chromatids

Kinetochores form

Mitotic spindles form

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3
Q

Describe prometaphase

A

Chromosomes move in active motion

Fragments of nuclear envelope are present

Kinetochore microtubules are formed

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4
Q

Describe metaphase

A

2 spindle poles are present

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

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5
Q

Describe anaphase

A

Kinetochore shortens

spindle poles move outward

daughter chromosomes separate between the 2 poles

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6
Q

Describe telophase

A

Daughter chromosomes are present at spindle poles

contractile ring forms in center

Nuclear envelope reassembles around each daughter chromosome bundle

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7
Q

How long does telophase take?

A

~5 hours

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8
Q

Describe cytokinesis

A

Completed nuclear envelope surrounds deconsensing chromosomes

Contractile ring creates deep cleavage furrow

Reformation of interphase microtubules and centosome

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9
Q

What are permanent cells?

A

Cells that exit the cell cycle and cannot come back.

Non-renewable

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10
Q

What are stable cells?

A

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

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11
Q

Where would stable cells enter the cell cycle?

A

G0

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12
Q

What is G1 of the cell cycle?

A

Growing phase (Interphase)

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13
Q

What is S of the cell cycle?

A

DNA synthesis phase (Interphase)

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14
Q

What is G2 of the cell cycle?

A

Growing phase (Interphase)

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15
Q

What is M of the cell cycle?

A

Nuclear and cellular division (Mitosis)

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16
Q

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

A

Hair cells in ear
Nerve cells

Parenchymal cells in liver
Smooth muscle cells

17
Q

Cells that continuously divide are called what kind of cells?

A

Labile cells

18
Q

Name 2 examples of labile cells

A

Epithelium, hematopoietic cells

19
Q

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

A

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

20
Q

How do epithelium cells of the GI tract differentiate?

A

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

The are shed from the villi in ~5 days

21
Q

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

A

COX-1

22
Q

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

A

Yes

23
Q

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

A

Yes

Estrogen
Testosterone
Norepinephrine (exercise)

24
Q

What are the check points of the cell cycle?

A

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

25
Q

What is does the G1/S check point ensure?

A

Appropriate growth signal
Cell size
Environment
DNA

26
Q

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

A

Cells shrunken from malnutrition would divide

27
Q

What does the G2/M check point ensure?

A

DNA duplication after S phase is okay

Cell size

28
Q

What does the M check point ensure?

A

Chromosomes are correctly distributed

29
Q

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

A

Has specific phosphate been removed?

Has specific phosphate been added?

Is cyclin present?

If yes, then output

30
Q

Describe the Cyclin D G1/S check point pathway

A

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)

31
Q

What is pRB? What cancer is it associated with?

A

retinoblastoma protein

Eye tumors

32
Q

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

A

During mitosis

33
Q

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

A

Cell senses injury

Cell transcribes p53

p53 inhibits cell cycles and instead induces transcription of repair enzymes

34
Q

How does p53 inhibit cell cycle?

A

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

35
Q

Is p53 inhibition of the cell cycle permanent?

A

No, only until the cell is repaired