Cell cycle Flashcards

1
Q

What is cell proliferation for?

A

Normal development
Homeostasis
Replace dead/injured cells

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2
Q

What are the 3 classes of proliferative capacity?

A
  • Labile cells - continuously divide
  • Stable cells - infrequent divisions
  • Permanent cells - never divide in adult life
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3
Q

What is the difference between pluripotent & totipotent stem cells?

A

Pluripotent - ability to self-renew & produce multiple types of specialised cells (adult stem cells)
Totipotent - give rise to all types of cells (embryonic SC)

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4
Q

What stimulates cell proliferation?

A

Growth factors

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5
Q

Describe the cell cycle

A
  • G0 - cell resting/quiescent
  • G1 - prepares DNA for synthesis
  • S - DNA replicates
    G2 - nuclear envelope broken down, mitotic spindle assembled & chromosomes aligned
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6
Q

What are the 5 steps in mitosis?

A
  1. Prophase - chromosomes shorten
  2. Metaphase - chromosomes line up along equator
  3. Anaphase - spindle fibres shorten & pull chromosomes apart
  4. Telophase - chromosomes unravel & nuclear envlope reform
  5. Cytokinesis - division of cytoplasm
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7
Q

What are the positive & negative controls of the cell cycle?

A

Positive - signals from outside cell (e.g. GF)

Negative - cyclin kinase inhibitors, checkpoints

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8
Q

Where are the checkpoints in the cell cycle and what do they do?

A

G1-S - monitors integrity of DNA before synthesis

G2-M - monitors integrity of replicated DNA

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9
Q

What may happen if a checkpoint is activated?

A
  • Activate DNA repair mechanism & resume replication
  • Apoptosis
  • Permanent senescence
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10
Q

Which checkpoint does P53 act?

A

At the G1-S checkpoint.
Senses DNA damage & binds to it cause gene expression to -
- Induce p21 (CKD inhibitor) - stop cell cycle
- Trigger apoptosis
- Activate DNA repair

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11
Q

What is hyperplasia?

A

Increased cell number.

Cell must be labile or stable

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12
Q

What is hypertrophy?

A

Increased cell size.

Occurs in any cells.
Common when permanent cells have increased demands.
More cellular structural proteins produced.

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13
Q

What is atrophy?

A

Decreased cell size.

Loss of cell substance due to autophagy of organelles

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14
Q

What is metaplasia?

A

Reversible change from one adult cell type to another.

Adaptive response.
Usually involves epithelium

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15
Q

What is dysplasia?

A

Increased cell growth

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16
Q

What is neoplasia?

A

Abnormal growth of cells which persist after initiating stimulus has been removed