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PMP101 - Health, Disease and Patient > The eukaryotic cell cycle > Flashcards

The eukaryotic cell cycle Flashcards

1
Q

What is a cell cycle?

A

series of cyclic events for cell duplication and division, essential for all
living things to reproduce/grow

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2
Q

What type of cells rarely divide?

A
  • muscle cells
  • nerve cells
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3
Q

What type of cell divides only once a year or two?

A

cells in the liver

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4
Q

What type of cells divide twice a day?

A

cells in the gut

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5
Q

What are the four phases of cell division?

A
  1. G1
  2. S phase
  3. G2
  4. M phase
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6
Q

What is the G0 phase?

A

a resting phase where non dividing cells reside

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7
Q

What is M phase comprised of?

A
  • mitosis
  • cytokinesis
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8
Q

Where does the cell cycle control system checkpoints occur?

A
  • between G1 and S phase
  • between G2 and M phase
  • between metaphase and anaphase
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9
Q

What do these checkpoints do?

A

It ensures that all the events required in each phase
are completed before the next one begins
▪ If not, it halts the cell cycle
▪ or enter the G0 resting phase (outside cell cycle)
▪ or activate apoptosis

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10
Q

What is a cdKS?

A

Cyclin-dependent kinases

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11
Q

What happens in Cdk activation?

A
  • Cdks require specific cyclins to become active
  • cyclins regulate the activation of Cdks
  • Cdks have to be phosphorylated to be active
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12
Q

What happens in the G1 phase?

A

Period of metabolic activity, cell growth, and
general repair to prepare the cell for division

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13
Q

What happens in the G2 phase?

A

In the S phase, each chromosome (nuclear
DNA) is replicated
▪ S-Cdk activates helicases and other enzymes
to initiate DNA replication
▪ Chromosomes are not yet visible in their X-
shape; they exist as chromatin

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14
Q

What is a centrosome?

A
  • centrosome is a cellular structure that controls the microtubules organisation within the cell
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15
Q

What happens in the G2 phase?

A
  • rapid cell growth and protein synthesis in preparation of mitosis
  • through check for unreplicated/ damaged DNA
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16
Q

What are the stages in M phase?

A

mitosis
cytokinesis

17
Q

What happens in the prophase?

A

chromatin is condensed into distinct visible chromosomes
* all nuclear activities are ceased
* outside the nuclear, mitotic spindle assembles between the 2 chromosomes which have begun to move apart

18
Q

What happens in the prometaohase?

A
  • Nuclear envelope disintegrates
  • The 2 centrosomes are at the spindle poles (opposite ends) of the cell
    *Chromosomes are attached to spindle microtubules of one pole via their
    kinetochores
19
Q

What happens in metaphase?

A
  • mitotic spindle is fully developed
  • Kinetochores on each sister chromatid attach to opposite poles of the spindle
  • The chromosomes are aligned on the spindle equator
  • M checkpoint controls the proper chromosome alignment and attachment
20
Q

What happens during anaphase?

A
  • Cohesins, holding sister chromatids together, break down → X-shaped chromosomes
    ▪ Because kinetochore microtubules shorten and the spindle poles also move apart
  • Sister chromatids of each chromosome segregate (now individual chromosomes)
    and are pulled toward the opposite spindle poles
21
Q

What happens in the telophase?

A
  • The two sets of chromosomes arrive at the spindle poles and decondense
  • It starts the cytoplasm division → formation of the contractile ring, between poles
  • Nuclear envelopes and lamina reassembles around each set of chromosomes,
    ➢formation of two nuclei → final event of mitosis
22
Q

What happens in cytokinesis?

A

The cytoplasm is divided in two by the contraction of contractile ring, which
pinches the cell into two daughters → each with one nucleus (same DNA)

23
Q

What is apoptosis?

A

Programmed cell death induced by internal and external stimuli

24
Q

When does apoptosis happen?

A
  • removing cells during embryonic development
  • cells no longer needed
  • cells with severe DNA damage
  • cells infected by viruses (prevents damage to neighbour cells)
25
Q

What is necrosis?

A

cell death due to acute injury
* non-controlled event → cells rupture = inflammation

26
Q

What do initiator caspase do?

A
  • can activate downstream capases
  • which break down key proteins
27
Q

What does not enough apoptosis lead to?

A
  • can allow cancer cells to grow
  • disease to spread
28
Q

What does too much apoptosis lead to?

A
  • excessive cell loss
  • e.g Alzheimers due to loss of neurones

PMP101 - Health, Disease and Patient (20 decks)

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