9.3: The eukaryotic cell cycle is regulated by a molecular control system Flashcards

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1
Q

Why does the frequency of cell division differ from each cell

A

due to regulation at a molecular(within the cell)

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2
Q

What is the cell cycle driven by

A

The cell cycle is driven by specific signaling molecules present in the cytoplasm

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3
Q

Where is evidence of cytoplasmic signals drawn from

A

When 2 cells were fused together, Cytoplasmic signals from one of the fused cells could cause the nucleus from the second cell to enter the same stage of the cell cycle as the first cell

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4
Q

cell cycle control system

A

an operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle controls the cell cycle

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5
Q

checkpoints

A

the cell cycle is a control point where stop and go-ahead signals can regulate the cycle

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6
Q

cyclins

A

(1)proteins that regulate the cell at a molecular level by a set of regulatory proteins and protein complexes, you have different fluctuations of these

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7
Q

CDKS(Cyclin-dependent kinases)

A

(2)type of protein kinase that regulates the cell at a molecular level, are inactive until they bind with cyclins and then are called MPFs

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8
Q

What goes on in the G1 checkpoint

A

known as the restriction point, the G1 checkpoint seems to be the most important checkpoint, If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2, and M phases, monitored by cyclin-CDK complexes

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9
Q

G0 phase

A

if the go-ahead signal is not received in G1, the cell goes into this phase where it is in a nondividing state(like the muscle and nerve cells) but can be called back from this phase(liver cells)

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10
Q

MPF(maturation-promoting factor)

A

cyclin-Cdk complex(attached together) that triggers a cell’s passage past the G2 checkpoint and into the M phase

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11
Q

Explain the G2 checkpoint

A

critical MPF levels are required in order to go onto the M phase, this is incase error occurs in chromsomes

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12
Q

Explain the fluctuations in MPF, Cyclins, and CDKs through the cell cycle

A

The MPF and cyclins are low until right up until the M checkpoint, the CDKs are constant through the whole thing

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13
Q

Explain the degradation of cyclin

A

CDK is constant until a cyclin attaches around the G2 phase starting, then the cyclin degrades and breaks at the end of the M phase

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14
Q

M checkpoint, what happens?

A

A stop signal is received if any of the chromosomes are not attached to a microtubule.

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15
Q

Explain one example of internal signals

A

M phase checkpoint has an internal signal where the anaphase does not begin until the chromosomes are all attached to microtubules

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16
Q

Explain one example of external signals

A

growth factors tell certain cells to divide

17
Q

What is the significance of PDGF in terms of growth factors

A

PDGF is needed to secrete a growth factor or else the cells will not divide, they also let you pass the G1 phase

18
Q

what checkpoint do most cells not get past

A

G1 because most cells just go to G0

19
Q

density-dependent inhibition

A

where crowded cells stop dividing and if there is a vacancy of cells, cells divide until it is filled

20
Q

anchorage dependence

A

where the cells need to be attached to something in order to divide

21
Q

what makes cancer cells so rapid growth-wise

A

Cancer cells have neither density-dependent inhibition nor anchorage dependence, they do not respond to signals

22
Q

How do cancer cells divide?

A

They make their own growth factors or divide without the signal itself due to a faulty cell cycle control system

23
Q

transformation

A

where the normal cell becomes a cancerous cell

24
Q

how are tumors formed

A

when cancer cells are not eliminated by apoptosis, tumors are masses in otherwise healthy tissues

25
Q

Benign tumor

A

if abnormal cells remain only at the original sits, is the lump, not bad

26
Q

Malignant tumors

A

invade surrounding tissues and can metastasize, where the cells export more cancerous cells to other parts of the body where additional tumors form

27
Q

2 types of cancer therapy

A

High energy radiation damages DNA in cancer cells and even more DNA in normal cells and Chemotherapeutic drugs interfere with not only cancer cell division, but also normal cell division

28
Q

Why is cancer so hard to treat

A

cancer is unique to the person, cancer is very complex

29
Q

What are the 3 molecules that control the cell cycle

A

CDK, Cyclins, MPF

30
Q

Why does cyclin fluctuate

A

Cyclins are constantly degrading

31
Q

What molecule moves the cell cycle

A

MPF