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Flashcards in Cell Cycle Deck (130)
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1

What 2 things must cells be able to do

Multiple and differentiate

2

What did Virchow say

When

“Omnis cellula e cellular”

1858

3

What is used to mark when observing DNA

Histones

4

Cancer is a disease of hyperplasia
True or false

True

Therefore many treatments inhibit cell division

5

Other than cancer, what diseases affect the cell cycle

Some Viruses cause hyperplasia and even cancer

Cylcomodulins allow pathogenic bacteria to control the host cell cycle

Rare genetic diseases eg microcephaly can be caused by cell cycle mutations

6

What are the phases of the cell cycle

M -> G1 -> S -> G2
⬆️ ⬇️ ⬆️⬅️⬅️⬅️⬅️⬅️⬅️

7

What is S phase

Synthesis phase (DNA replication)

Making a perfect copy of the genome

8

What is M phase

Mitosis and cytokenesis

Nuclear division - splitting DNA between 2 daughter cells

9

What is cytokinesis

Cytoplasmic division

10

What happens in the gap phases

Critics for maintaining cell size

Cell growth

Also where cell responds to cues

11

What is G0 phase

When is it

Prolonged exit from cell cycle


Early G1 phase

12

Which cycle phase must cancers overcome to induce hyperplasia

G0

13

When do cells only go through half the cycle

Never - it is an all or nothing process

14

What keeps the cell cycle as an all or nothing process

Check points - you can proceed unless the previous phase is complete

15

What are the cell cycle checkpoints

Spindle assembly checkpoint (SAC)
START (G1/S checkpoint) - commit to entire cycle
G2/M checkpoint - is replication complete

16

How do you build a molecular switch

Enzyme is only active when bound to a cofactor which then inhibits the inhibitor of the enzyme creating a bistable switch

17

What is the graph of Cofactors concentration vs enzyme activity if the enzyme requires the cofactors to be active

Hyperbolic relationship - increases until enzyme is saturated then plateau

18

What is the graph of a bistable switch

Cofactors concentration vs enzyme activity

Shallow positive gradient (off), then v steep gradient, then shallow (on)

19

Explain bistable switch phases

Off- when inhibitor concentration is high and cofactor concentration is low - inhibitor is winning so enzyme is “off”

Steep- after a critical point when enough enzyme is activated to inhibit the inhibitor - positive feedback loop - rapid enzyme activation

On- all enzymes are on

20

What do bistable switches ensure

You can only go one way and the phase is completed in full

21

What is the master regulator in the cell cycle

Cyclin Dependent Kinase (CDK)

22

What do kinases do

Transfer phosphates usually from ATP to a substrate

23

How does CDK act on its own

It doesn’t it is inactive by itself

It must be activated by binding to different cyclins in different phases of the cell cycle

24

Which cyclin is present in G1

What does it activate

Cyclin E

CDK2

25

Describe how the cyclins change in concentration throughout the cell cycle

Cyclin E is high in G1
Cyclin A begins to rise after the START checkpoint and remains high throughout S and G2. Cyclin A then drops at G2/M checkpoint, falling to 0 by the middle of M phase
Cyclin B begins to rise at the end of S phase, rises throughout G2 and plateaus in the first half of M phase and drops to 0 after the SAC checkpoint

26

What does cyclin A activate

CDK2

27

What does cyclin B activate

CDK1

28

When do cyclin D levels rise

What does it activate

G1

CDK4/6

29

Which cyclin and CDK is necessary for replication of genome (S phase)

Cyclin A
CDK2

30

Which cyclin and CDK is necessary for mitosis

Cyclin B
CDK 1