1.5 Protein Control of Cell Division Flashcards Preview

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Flashcards in 1.5 Protein Control of Cell Division Deck (43)
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1
Q

what does the cytoskeleton do

A

gives mechanical support and shape to cells

2
Q

what does the cytoskeleton consist of

A

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

3
Q

what are microtubules

A

hollow cylinders composed of the protein tubulin

4
Q

where are the microtubules found

A

they radiate from the microtubule organising centre (MTOC) or centrosome

5
Q

what do microtubules do

A

control the movement of membrane-bound organelles and chromosomes

6
Q

what does cell division require

A

remodelling of the cytoskeleton

7
Q

what does formation and breakdown of microtubules involve

A

polymerisation and depolymerisation of tubulin

8
Q

what do microtubiles form

A

the spindle fibres that are active during cell division

9
Q

what does the cell cycle consist of

A

interphase and mitotic (M) phase

10
Q

what does the interphase involve

A

growth and DNA synthesis including:
G1, a growth phase,
S phase, during which the DNA is replicated,
and G2, a further growth phase

11
Q

what does the mitotic phase involve

A

mitosis and cytokinesis

12
Q

what happens in mitosis

A

the chromosomal material is separated by the spindle microtubules
this is followed by cytokinesis

13
Q

what happens in cytokinesis

A

the cytoplasm is separated into two daughter cells

14
Q

what does mitosis consist of

A

prophase
metaphase
anaphase
telophase

15
Q

what is prophase

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 region

(think pro means before)

16
Q

what is metaphase

A

chromosomes are alligned at the metaphase plate (equator of the spindle)

(think middle)

17
Q

what is anaphase

A

as spindle microtubules shorten by depolymerisation, sister chromatids are seperated, and the chromosomes are pulled to opposite poles

(think away)

18
Q

what is telophase

A

the chromosomes decondense and nuclear membranes are formed around them

(think two)

19
Q

what is progression in the cell cycle controlled by

A

checkpoints

20
Q

what are checkpoints

A

mechanisms within the cell that assess the condition of the cell during the cell cycle and halt progression to the next phase until certain requirements are met

21
Q

what is involved in regulating the cell cycle

A

cyclin proteins that accumulare during cell growth

22
Q

what do cyclins combine with

A

they combine with and activate cyclin-dependent kinases (CDKs)

23
Q

active cyclin-CDK complexes phosphorylate

A

proteins that regulate progression through the cycle

if sufficient phosphorylation is reached, progression occurs

24
Q

what happens at the G1 checkpoint

A

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

25
Q

what does phosphorylation by G1 cyclin-CDK inhibit

A

the retinalblastoma protein (Rb)

26
Q

what does the inhibation of Rb allow

A

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

27
Q

what happens at G2 checkpoint

A

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

28
Q

what does DNA damage trigger

A

the activation of several proteins including p53

29
Q

what is p53

A

it can stimulate DNA repair,
arrest the cell cycle,
or cause cell death (apoptosis)

30
Q

what does a metaphase checkpoint control

A

the progression from metaphase to anaphase

31
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

32
Q

what can an uncontrolled reduction in the rate of the cell cycle result in

A

degenerative disease

33
Q

what can an increase in the rate of the cell cycle result in

A

tumour formation

34
Q

what is a proto-oncongene

A

a normal gene, usually involved in the control of cell growth or division, which c an mutate to form a tumour-promoting oncogene

35
Q

what triggers apoptosis

A

apoptosis is triggered by cell signals that can be external or internal

36
Q

what is an example of an external death signal

A

the production of death signal molecule from lymphocytes

37
Q

what is an example of internal death signal

A

DNA damage

38
Q

what do external death signal molecules bind to

A

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

39
Q

what does an internal death signal resulting from DNA damage cause

A

activation of p53 tumour-suppressor protein

40
Q

what do both internal and external death signal result in

A

the activation of caspases that cause the destruction of the cell

41
Q

what is caspases

A

types of protease enzyme

42
Q

why is apoptosis essential during development of an organism

A

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

43
Q

what can happen in the absence of growth factors

A

cells may initiate apoptosis