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Week 1 (20-24) > 21 - cell cycle > Flashcards

21 - cell cycle Flashcards

1
Q

What is the G1 phase?

A

-Synthesis of proteins, organelles -First growth phase -Time varies

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2
Q

What is a Mitogen and which phase does work with?

A

Mitogen stimulates growth by pushing cell division. -Mitogens function via cyclin dependent kinases (Cdks) Present in G1

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3
Q

What is the S phase?

A

-Synthesis of DNA -1 chromosome = 2 sister chromatids

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4
Q

What is the G2 phase?

A

-Growth in preparation for Mitosis

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5
Q

What is the G0 phase?

A

-May occur in absence of mitogen stimulation -It is not a dividing state, most cells are here

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6
Q

What cells are always in G0?

A

Neurons, Skeletal muscle

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7
Q

Which cells are often in G0?

A

Liver cells

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8
Q

Which cells go in and out of G0?

A

Fibroblast and Lymphocytes

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9
Q

What are Labile cells?

A

-Rapidly dividing -Never in G0

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10
Q

Example of Labile cells?

A

Bone marrow, GI epi cells, hair follicles

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11
Q

Why does chemotherapy effect Labile cells?

A

Because they are always dividing, never in G0

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12
Q

Phases of Mitosis?

A

-Prophase -Prometaphase -Metaphase -Anaphase Telophase

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13
Q

Prometaphase

A

-Chromosomes organize on mitotic spindle

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14
Q

Metaphase

A

Chromosomes line up on metaphase plate

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15
Q

Anaphase

A

Chromosomes seperate

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16
Q

Telophase

A

Spindle breaks down and the the cell divides (Cytokinesis)

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17
Q

Checkpoints curing the cell cycle?

A

G1-S (Prior to S phase entry)

G2-M (Prior to Mitosis)

M phase (Prior to anaphase/cytokinesis)

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18
Q

What do all check points depend on? and how do you activate them?

A

Cyclin dependent kinases (Cdks)

  • Cdks are always present but inactive, they are activated by cyclins
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19
Q

What happens if there is damage found in G1? and what is present??

A

Cell division is stopped

  • ATM pathway (activated by double strand breaks)
  • ATR pathway (single stranded break)

P53 is phosphorylated and induces p21. P21 protein binds to Cdks and the progression is stopped.

20
Q

Retinoblastoma

A
  • Rare childhood eye malignancy
  • Abnormal Rb resulting in free E2F = unregulated cell growth
21
Q

Li-Fraumeni Syndrome

A
  • Multiple malignancies at early age
  • mutation in P53 = no arrest if damage present
22
Q

What are the five stages of prophase I?

A

Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis,

23
Q

What is happening in Leptotene?

A

Sister chromosomes connect

24
Q

What is happening in Zygotene?

A

Form the synaptonemal complex (binds chromosomes together)

25
What is happening in the Pachytene phase?
The synaptonemal complex is complete
26
What is happening in the Diplotene?
The Synaptonemal complex begins to break down
27
What is happening in the Diakinesis?
The nucleus and the nuclear envelope disapear.
28
2 events in meiosis that increase genetic diversity?
Random assortment and crossing over
29
What is the role of telomerase?
Prevents the loss of DNA by putting a Guanine chain on the end.
30
3 major types of protein filament that form the cytoskeleton?
Actin, Intermediate, and microtubules
31
Function of the centrosome? and which end points out of the centrosome?
Organize microtubules and initiate microtubule formation. The positive is pointing out and the negative is in.
32
What are the microtubule motors?
Dynein, move in (-) retrograde direction Kinesin, move in (+) anterograde direction
33
Steady state
A state that doesnt change with time and that needs energy
34
Equilibrium
When everything stays the same with no energy change
35
Negative Feedback Loop
Just trying to return to equilibrium
36
Positive feedback
Amplification of an effect
37
Feed-Forward
Anticapation for a change in a variable before it happens
38
What are the set point deviations?
Circadian rhythm, environmental changes, protective response, ageing
39
G1 phase regulation?
Cyclin D, Cdk4/6 Rb p53
40
S phase regulation?
Cyclins E and A, Cdk2
41
G2 phase regulation?
Cyclin A, Cdk 1
42
M phase regulation?
Cyclin B, Cdk 1 APC
43
cdc25c?
cell division cycle 25C triggers G2 to M progression
44
45

Week 1 (20-24) (14 decks)

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