1.5 Flashcards

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1
Q

What is the function of the cytoskeleton?

A

Gives mechanical support and shape to cells and consists of different protein structures.

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2
Q

What is the structure of microtubules?

A

Protein structures and are hollow cylinders composed of tubulin

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3
Q

Where do microtubules radiate from?

A

The MTOC (microtubules organising centre) aka the centrosome

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4
Q

The formation and breakdown of microtubules involved…

A

Polymerisation and depolymerisation

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5
Q

What does cell division allow?

A

Allows organisms to grow, develop, replace dead cells and so repair tissues

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6
Q

What does the length of the cell cycle depend on?

A

Type of cell and external factors.

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7
Q

What are the two main phases of the cell cycle?

A

Interphase and Mitotic phase with cytokinesis

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8
Q

What does interphase include?

A

G1, S and G2

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9
Q

What does the M phase consist of?

A

Prophase, metaphase, anaphase and telophase.

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10
Q

What is cytokinesis?

A

When the two daughter cells are formed after cytoplasmic division

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11
Q

What happens in prophase?

A

Nuclear envelope breaks down and spindle microtubules attach to chromosomes.

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12
Q

What happens in metaphase?

A

Chromosomes aligned on the metaphase plate

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13
Q

What happens in anaphase?

A

Chromosomes are pulled to opposite sides by shortening microtubules

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14
Q

What happens in telophase?

A

Nuclear envelopes form round condensed chromosomes

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15
Q

Why are checkpoints required?

A

They are used to assess the cell’s condition during the cell cycle. Progression to the next phase will be halted until certain requirements are met.

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16
Q

Where are the checkpoints?

A

Near the end of G1, at the end of G2 and the metaphase of the M phase.

17
Q

What do cyclins do?

A

Accumulate during cell growth and are involved with regulating the cell cycle

18
Q

What do cyclins do with CDKs?

A

They combine with and activate them turning into cyclin CDKs. These complexes phosphorylase proteins that regulate protein.

19
Q

What does CDK stand for?

A

Cyclin dependent kinases

20
Q

If sufficient phosphorylation….

A

Progression ovcurs

21
Q

If insufficient phosphorylation….

A

Stop

22
Q

What happens at the G1 checkpoint?

A

Phosphorylation by G1 cyclinCDK inhibits Rb thus transcription of genes that code for the proteins needed for DNA replication takes place.

23
Q

What is Rb?

A

Retinoblastoma protein is a tumour suppressor as it inhibits gene transcription coding for proteins needed for DNA replication.

24
Q

What happens at the G2 checkpoint?

A

Any damage to DNA is assessed and if there is DNA damage this triggers the activation of the p53 protein.

25
Q

What does activation of p53 do?

A

Either;
1. Stimulation of DNA repair
2. Arrest the cell cycle
3. Initiate cell death (apoptosis)

26
Q

What does the M checkoint control?

A

Progression from metaphase to anaphase

27
Q

What is progression conditional on in the M checkpoint?

A

The chromosomes being correctly aligned on the equator and attached to the spindle microtubules.

28
Q

What causes a degenerative disease?

A

uncontrolled cell death

29
Q

What causes a tumour?

A

uncontrolled cell cycle

30
Q

What is a proto-oncogene?

A

a normal gene involved in the control of cell growth or division.

31
Q

What can proto-oncogenes mutate to form and what happens next?

A

Tumour-promoting oncogene resulting in uncontrolled cell division

32
Q

What is apoptosis?

A

A normal, genetically regulated process leading to the death of cells and triggered by the presence or absence of certain stimuli, as DNA damage

33
Q

What is an example of an internal death signal?

A

DNA damage

34
Q

What is activated due to DNA damage?

A

p53 tumour suppressor protein

35
Q

What is activated due to DNA damage?

A

p53 tumor suppressor protein

36
Q

What do external death signals do?

A

These molecules bind to a surface receptor protein triggering a protein cascade within the cytoplasm

37
Q

What do internal and external signals end in?

A

The production of active caspases that cause the destruction of the cell.

38
Q

Why is apoptosis important?

A

Remove cells during development that are no longer required as development progresses or during metamorphosis eg between fingers and toes.