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Biology > Protein Control of Cell Division > Flashcards

Protein Control of Cell Division Flashcards

1
Q

What is the purpose of the cytoskeleton?

A

It gives mechanical support and shape to cells

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2
Q

What does the cytoskeleton consist of?

A

different protein structures including microtubules, which are found In all eukaryotic cells

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3
Q

What are microtubules?

A

hollow cylinders composed of the protein tubulin

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4
Q

Where do the microtubules radiate from?

A

The microtubule organising centre (MTOC) or centrosome

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5
Q

What do microtubules do?

A

control the movement of membrane-bound organelles and chromosomes

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6
Q

What do microtubules form that are active during cell division?

A

spindle fibres

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7
Q

What does the formation and breakdown of microtubules involve?

A

polymerisation and depolymerisation of tubulin

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8
Q

What does interphase involve?

A

growth and DNA synthesis

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9
Q

What phases does interphase include?

A

G1, S phase and G2

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10
Q

What is G1?

A

a growth phase

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11
Q

What happens during S phase?

A

The DNA is replicated

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12
Q

What is G2?

A

Further growth phase

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13
Q

In mitosis, what separates the chromosomal material?

A

The spindle microtubules

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14
Q

What is separation of the chromosomal material by spindle microtubules followed by?

A

cytokinesis

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15
Q

What is cytokinesis?

A

The process where the cytoplasm is separated into two daughter cells

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16
Q

What are checkpoints?

A

Mechanisms within the cell that assess the condition of the cell during the cell cycle

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17
Q

What do checkpoints do?

A

Halt progression to the next phase until certain requirements are met

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18
Q

When do cyclin proteins accumulate?

A

during cell growth

19
Q

What do cyclins do?

A

regulate the cell cycle

20
Q

What do cyclins combine with and activate?

A

cyclin-dependent kinases (CDKs)

21
Q

What do active cyclin-CDK complexes do?

A

phosphorylate proteins that regulate progression through the cycle

22
Q

At G1 checkpoint what does the retinoblastoma protein (Rb) act as?

A

A tumour suppressor; it inhibits the transcription of genes that code for proteins needed for DNA replication

23
Q

What does the phosphorylation by G1 cyclin-CDK do?

A

Inhibits the Rb

24
Q

What does the inhibition of Rb allow?

A

transcription of the genes that code for proteins needed for DNA replication

25
Q

What does inhibition of Rb enable?

A

the cells to progress from G1 to S phase

26
Q

What happens at G2 checkpoint?

A

the success of DNA replication and any damage to DNA is assessed

27
Q

What happens if any DNA damage is identified?

A

The activation of several proteins including p53 is triggered

28
Q

What does p53 do?

A

It can stimulate DNA repair, arrest the cell cycle or cause cell death

29
Q

What happens at the metaphase checkpoint?

A

progression is halted until the chromosomes are aligned correctly on the metaphase plate and attached to the spindle microtubules.

30
Q

What can uncontrolled increase /reduction in the rate of the cell cycle cause?

A

tumour formation i.e cancer and degenerative disease i.e alzheimers

31
Q

what do proto-oncogenes do?

A

usually involved in the control of cell growth or division

32
Q

Proto-oncogenes can mutate to form….

A

tumour-promoting oncogenes

33
Q

What can apoptosis be triggered by?

A

cell death signals that can be external or internal

34
Q

Example of external death signal?

A

The production of death signal molecules from lymphocytes

35
Q

Example of an internal death signals?

A

DNA damage

36
Q

What do external death signal molecules do?

A

Bind to a surface receptor protein and trigger a protein cascade within the cytoplasm

37
Q

What does an internal death signal do?

A

causes activation of p53

38
Q

What do both death signals activate?

A

caspases that cause the destruction of the cell

39
Q

When is apoptosis essential?

A

during development of an organism to remove cells no longer required as development progresses or during metamorphosis

40
Q

Why does apoptosis occur?

A

It removes cells no longer required as development progresses or during metamorphosis

41
Q

When may cells initiate apoptosis?

A

in the absence of growth factors

42
Q

What is apoptosis?

A

programmed cell death

43
Q

What are caspases?

A

a family of protein digesting enzymes

Biology (21 decks)

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