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AH Biology > Unit 1: KA5 - Protein Control of Cell Division > Flashcards

Unit 1: KA5 - Protein Control of Cell Division Flashcards

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1
Q

What is the cytoskeleton?

A

The cytoskeleton is a network of protein fibres inside the cell. It’s function is to provide mechanical support and shape to cells.

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2
Q

What is the cytoskeleton made of?

A

Different protein structures including microtubules (in eukaryotes).

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3
Q

What are microtubules?

A

Hollow cylinders composed of protein tubulin.

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4
Q

What is the function of microtubules?

A

They control the movement of membrane bound organelles and chromosomes.

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5
Q

What does microtubules’ formation and breakdown involve?

A

polymerisation and depolymerisation

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6
Q

What does cell division require?

A

remodelling of the cytoskeleton

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7
Q

What are spindle fibres?

A

When the cytoskeleton is remodelled, the disassembled microtubules form the spindle fibres.

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8
Q

What function do spindle fibres perform?

A

The spindle fibres control the movement of chromosomes during mitosis.

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9
Q

What are the two phases of the cell cycle?

A
  • Interphase

- Mitotic phase

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10
Q

What are the stages within the mitotic phase?

A 
Prophase 
Meta phase
Anaphase
Telophase
Cytokinesis
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11
Q

Describe prophase.

A
  • DNA condenses into chromatid pairs
  • Nuclear membrane breaks down
  • Spindle microtubules extend from centrosome to attach to chromosomes
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12
Q

What is the centrosome?

A

Microtubules radiate from the microtubule organising centre (MTOC) or centrosome.

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13
Q

Describe metaphase.

A
  • Chromosomes line up at the metaphase plate (equator).
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14
Q

Describe Anaphase.

A
  • Spindle microtubules shorten by depolymerisation

- Sister chromatids are separated and the chromosomes are pulled to opposite poles.

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15
Q

At what point do spindle fibres attach to chromosomes?

A

The kinetochore

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16
Q

Describe Telophase

A
  • Nuclear membrane forms around chromosomes

- Chromosomes begin to uncoil (decondense).

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17
Q

Describe cytokinesis

A
  • Separation of the cytoplasm to form 2 identical daughter cells.
18
Q

What is progression through the cell cycle regulated by?

A

Checkpoints

19
Q

What are the 3 sections of interphase, and describe them

A

G1 - Growth: growth of proteins and organelles
S - Synthesis: DNA replication
G2 - Growth: growth of proteins and organelles

20
Q

What proteins are involved in regulating the cell cycle?

A

cyclins

21
Q

What does the Retinoblastoma protein do?

A

At the G1 checkpoint, retinoblastoma protein (Rb) acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication .

22
Q

How is Rb deactivated?

A

phosphorylation by G1 cyclin-CDK

23
Q

What is assessed at the G2 checkpoint?

A

Success of DNA replication

damage to DNA

24
Q

What is G₀?

A

If the cell does not pass the G1 checkpoint, it enters G₀, a resting phase.

25
Q

What is CDK?

A

Cyclin Dependent Kinase.

26
Q

What may an uncontrolled increase in the rate of the cell cycle result in?

A

Formation of a tumour

27
Q

What may an uncontrolled reduction in the rate of the cell cycle result in?

A

a degenerative disease

28
Q

What 3 checkpoints are there?

A

G1
G2
Metaphase

29
Q

Name the protein that is activated by DNA damage.

A

p53

30
Q

What 3 things can p53 do after identification of cell damage at the G2 checkpoint.

A
  • Stimulation of DNA repair
  • Cause cell death
  • Arrest of cell cycle
31
Q

What does the metaphase checkpoint assess?

A

Ensure chromosomes are aligned correctly on metaphase plate and attached to the spindle microtubules.

32
Q

Define the term proto-oncogene

A

A proto-oncogene is a normal gene that is involved in the control of cell growth or division.

33
Q

Describe the effects of a mutation within a proto onco-gene.

A

formation of a tumour promoting oncogene.

34
Q

Define the term apoptosis.

A

Apoptosis is the carefully controlled destruction of cells.

35
Q

How is apoptosis triggered?

A

Internal or external death signals

36
Q

What two processes are apoptosis required in?

A
  • Development of an organism

- metamorphosis

37
Q

Describe how external death signals work and give an example of a molecule that produces one.

A

Death signals can be produced by lymphocytes

These signal molecules bind to receptor proteins on surface of cell and trigger a protein cascade of caspase proteins

38
Q

What is caspase?

A

A type of protease that causes the destruction of the cell by triggering degradation of any protein.

39
Q

Describe the internal pathway of apoptosis.

A

A death signal is created and activates p53.

Cells may initiate apoptosis in the absence of growth factors.

40
Q

Give examples of internal death signals

A
  • DNA damage activates p53

- absence of growth factors

AH Biology (13 decks)

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