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cell cycle Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

explain the what happens to cohesins when microtubules bind to centromeres

A

cyclins break down along the length of the chromosome apart from at the centromere

these cohesins break down last to prevent aneuploidy

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2
Q

name some cohesinopathies

A

Roberts syndrome
Conerlia de Lange syndrome
Non-disjunction of chromosomes

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3
Q

what are CDKs?

A

cyclin dependent kinases - regulate progression of the cell cycle

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4
Q

what activates CDKs?

A

cyclins

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5
Q

what does the retinoblastoma protein do?

A

inhibits E2F proteins by binding to them

stops cells from going past G1 into S phase

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6
Q

what happens when Cdk2 is activated?

A

inactivates Rb by phosphorylation so E2F is released so the cell can enter S phase

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7
Q

explain the role of p53 in controlling the progression of the cell cycle

A

p53 is a transcription factor
binds to the gene for p21
p21 controls whether or not cyclin-Cdk2 can activate E2F by phosphorylating Rb

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8
Q

how does the mutation of the RB1 protein lead to cancer?

A

mutation means no functional Rb
no Rb binds to E2F
E2F doesnt stop cell from entering S phase
uncontrolled proliferation –> cancer

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9
Q

what are the three cell cycle checkpoints?

A

end of G1
G2-M transition
Mitosis (metaphase)

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10
Q

what happens at the end of G1 checkpoint?

A

checks cell size, growth factors and DNA damage

controlled by p16 which inhibits CDK 4/6 so it cant interact with cyclin D

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11
Q

what happens in the G2-M checkpoint?

A

checks DNA replication, damage and cell size

stops cell cycle if there’s damage

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12
Q

what happens in the mitosis checkpoint?

A

checks that the chromosomes are attached to the spindles

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13
Q

what are the three main types of chemotherapy?

A

anti-mitotics
biologics
antihormonal drugs

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14
Q

what are the two classes of anti-mitotics?

A

vinca-alkaloids

taxanes

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15
Q

what do vinca alkaloids do?

A

prevent microtubule formation

metaphase cannot occur

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16
Q

what do taxanes do?

A

prevent the microtubule disassembly

cells cant enter telophase

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17
Q

what are biologics?

A

monoclonal antibodies

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18
Q

when are anti-hormonal chemotherapies used for?

A

hormone driven cancers

caused by overexpression of a receptor or sensitive to a hormone

19
Q

what stages form interphase?

A

g1
s
g2

20
Q

what happens during G1 and G2?

A

no DNA synthesis

environment is monitored

21
Q

what happens in G1?

A

Monitors internal and external environmental conditions to ensure it is suitable for mitosis.

22
Q

what happens in G2?

A

double checks DNA has been copied properly. Any mistakes are repaired, if they are unable to be repaired the cell undergoes apoptosis

23
Q

what happens in S phase?

A

DNA replication

2n to 4n

24
Q

what are the stages of mitosis?

A 
o	Prophase
o	Metaphase
o	Anaphase
o	Telophase 
o	Cytokinesis
25
Q

what happens in prophase?

A
  • DNA condenses into visible chromosomes
  • nucleoli disappears
  • nuclear membrane breaks down
  • chromosomes join at the centromeres
  • centrioles move to the poles in pairs
  • microtubules radiate and attach to chromosomes
26
Q

what is the kinetochore?

A

how microtubules attach to the centromere of a chromosome

27
Q

describe the structure of the kinetochore

A

inner region - binds to centrosome (present throughout cell cycle)
outer region - interacts with microtubules (made during cell division)

28
Q

what happens during metaphase?

A
  • Kinetochore / microtubules are used to pull chromosomes apart – one from each pair of sister chromatids pulled towards opposite ends
  • Chromosomes line up in the middle
  • Centrosomes are at the polar ends of the cell
29
Q

what happens in anaphase?

A
  • Sister chromatids are separated by the microtubules
  • Chromatids are pulled to polar ends
  • When chromosome reaches centrosome the poles separate further by elongation of the polar microtubules
30
Q

what is cohesin?

A

a protein to hold sister chromatids together

31
Q

what is aneuploidy?

A

presence of abnormal number of chromosomes

32
Q

how can aneuploidy occur?

A

if kinetochore doesnt attach to the microtubules properly so the sister chromatids dont separate

if cohesin doesnt break down so the chromatids dont separate

33
Q

what happens in telophase?

A
  • chromosomes arrive at polar ends
  • uncoiling of chromosomes
  • nuclear envelope reforms
  • cell’s pinched until it cleaves and forms 2 daughter cells
34
Q

what happens in cytokinesis?

A
  • Cytoplasm splits between the 2 cells

* Cell divides

35
Q

what is the purpose of meiosis?

A

specialised cell division to make gametes

36
Q

when does recombination occur?

A

prometaphase I of meiosis

37
Q

what happens in prophase I?

A

Recombination/crossing over.
o Microtubules and proteins extend across the cell. Membrane around the nucleus of the cell erodes and the chromosomes are set free

38
Q

what happens in metaphase I?

A

Chromosome pairs line up. Random assortment

39
Q

what happens in anaphase I?

A

spindles pull chromosome pairs apart

40
Q

what happens in telophase I?

A

Chromosomes finishing moving to their opposite poles

41
Q

what happens in prophase II?

A

Chromosomes condense, forming an X structure. Membrane around nucleus dissolves and chromosomes are released. Centrioles duplicate and meiotic spindle is formed.

42
Q

what happens in metaphase 2?

A
  • Chromosomes line up.
  • Centrioles are located at the poles of the cell.
  • Meiotic spindle attaches itself to each of the chromatids.
43
Q

what happens in anaphase 2?

A

chromatids are split and divided and pulled to the two opposite poles of the cell

44
Q

what happens in telophase 2?

A

Same as telophase I with the addition of cytokinesis, resulting in four gametes with distinct genetic information. Chromosomes finish moving to the poles

cell biology (17 decks)

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