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Adv Bio Unit 1 > 1.5- Cell Division > Flashcards

1.5- Cell Division Flashcards

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1
Q

What are the two functions of the cytoskeleton?

A

The cytoskeleton gives mechanical support and shape to cells.

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2
Q

What does the cytoskeleton consist of?

A

Different proteins including microtubules which are found in eukaryotic cells.

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3
Q

What are microtubules and what are they made of?

A

Hollow cylinders composed of the protein tubulin.

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4
Q

Where do microtubules radiate from?

A

The microtubule organising centre (MTOC) or centrosome.

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5
Q

Roles of the cytoskeleton (3)

A
  • provides mechanical support which allows the shape to be maintained
  • allows movement of cell organelles
  • allows the movement of whole cells (e.g. white blood cells)
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6
Q

Roles of the cytoskeleton in cell division (3)

A
  • control the movement of membrane-bound organelles and chromosomes
  • responsible for the division of the cytoplasm in animal cells (cytokinesis)
  • moves chromosomes in mitosis and meiosis
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7
Q

What happens to the cytoskeleton during cell division?

A

It is completely remodelled

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8
Q

Describe the formation and breakdown of microtubule

A

polymerisation and depolymerisation

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9
Q

The new name for centromere

A

kinetochore

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10
Q

Spindle fibres form the

A

mitotic spindle

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11
Q

microtubules form the ……… that are active during cell division

A

spindle fibres

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12
Q

What does the cell cycle consist of? (2)

A

Interphase and mitotic (M) phase

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13
Q

Interphase involves growth and DNA synthesis including:

A

G1- a growth phase
S phase- the DNA is replicated
G2- a further growth phase

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14
Q

What is the product of the cell cycle?

A

two genetically identical daughter cells

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15
Q

A functioning fully grown organisms is the result of….

A

a series of tightly controlled cell divisions

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16
Q

What are microtubules?

A

Hollow cylinders composed of the protein tubulin.

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17
Q

What does the mitotic phase involve?

A

mitosis and cytokinesis

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18
Q

In mitosis the chromosomal material is separated by the ……………. This is followed by…

A

spindle microtubules. This
is followed by cytokinesis, in which the
cytoplasm is separated into two daughter
cells.

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19
Q

What does mitosis consist of?

A

Prophase, metaphase, anaphase and telophase

20
Q

Order of mitosis stages

A

PMAT

prophase, metaphase, anaphase and telophase

21
Q

Describe prophase (1st stage of mitosis) (3)

A

DNA condenses into chromosomes each consisting of two sister chromatids
Nuclear membrane breaks down
Spindle microtubules extend from the MTOC by polymerisation and attach to chromosomes via their kinetochores in the centromere position

22
Q

Describe metaphase (2nd stage of mitosis) (1)

A

Chromosomes are aligned at the metaphase plate (equator of the spindle)

23
Q

Describe anaphase (3rd stage of mitosis) (2)

A

As spindle microtubules shorten by deploymerisation, sister chromatids are separated
Chromosomes are pulled to opposite poles

24
Q

Describe telophase (4th stage of mitosis) (2)

A

The chromosomes decondense

Nuclear membranes are formed around them

25
Q

Cells that proliferate rapidly and uncontrollably can form..

A

tumours

26
Q

Explain the two major phases in the cell cycle of a eukaryotic cell

A

Interphase: period of growth and DNA replication

M Phase: segregation of replicated chromosomes and division of cytoplasm to form 2 genetically identical daughter cells.

27
Q

Explain the three parts of interphase

A
  1. G1- initial growth phase. Protein synthesis occurs and new organelles are formed
  2. Synthesis (S)- Replication of nuclear DNA
  3. G2- second phase of growth prior to mitosis. By the end of this phase the centrosome has been duplicated
28
Q

Explain the two processes that occur during the M phase

A
  1. Mitosis- the accurate separation and distribution of replicated chromosomes and the formation of daughter nuclei
  2. Cytokinesis- the division of the cytoplasm into 2 separate daughter cells
29
Q

Why is cytokinesis regulated?

A

to ensure that it occurs at the right location and stage of the M phase

30
Q

How is cytokinesis achieved in animal cells?

A

By the action of a contractile ring of structural and regulatory proteins
A cleavage furrow is formed
The location of the ring is specified by the spindle fibres

31
Q

Progression through the cell cycle is controlled by

A

checkpoints

32
Q

What are checkpoints in the cell cycle?

A

Mechanisms in the cell that assess the condition of the cell during the cycle & halt progression to next phase until requirements are met

33
Q

Cyclin proteins that accumulate during cell

growth are involved in

A

regulating the cell cycle

34
Q

Cyclins combine with and activate…

A

cyclin-dependent kinases CDKs

35
Q

Active-cyclin CDK complexes ………… proteins that regulate progression through the cycle.

A

phosphorylate

If sufficient phosphorylation is reached, progression occurs.

36
Q

What happens at the G1 checkpoint?

A

Retinoblastoma protein (Rb) acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication

37
Q

Phosphorylation by G1 cyclin-CDK inhibits the…

A

retinoblastoma protein (Rb)

38
Q

Phosphorylation by G1 cyclin-CDK inhibits

the retinoblastoma protein (Rb). What does this allow?

A

Allows the transcription of genes that code for proteins needed for DNA replication. Cells progress from G1 to S.

39
Q

What happens at the G2 checkpoint?

A

The success of DNA replication & damage to DNA is assessed.
DNA damage triggers the activation of proteins including p53 that can stimulate DNA repair, arrest the cell cycle or cause cell death.

40
Q

What is p53?

A

A protein that can stimulate DNA repair, arrest the cell cycle or cause cell death.

41
Q

What happens at the metaphase checkpoint (M)?

A

Controls progression from metaphase to anaphase.
Progression is halted until the chromosomes are aligned correctly on the metaphase plate & attached to spindle microtubules.

42
Q

An uncontrolled reduction in the rate of the cell cycle may result in…

A

degenerative disease

43
Q

An uncontrolled increase in the rate of the cell cycle may result in…

A

tumour formation

44
Q

Proto-ongogene

A

a normal gene usually involved in the control of cell growth/division
can mutate to form a tumour-promoting oncogene

45
Q

What is apoptosis triggered by?

A

cell death signals (external or internal)

46
Q

Example of an external cell death signal

A

production of death signal molecules from lymphocytes

47
Q

Example of an internal cell death signal

A

DNA damage

Adv Bio Unit 1 (6 decks)

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