Cell differentiation and cell cycle

Question 1

What is cell differentiation?

Answer 1

A process by which less specialised cells become more specialised.

Question 2

How does differentiation affect a cell?

Answer 2

Can affect its:
Size.
Shape.
Metabolic activity.
Responsiveness to signals.

Question 3

Name some scenarios where cell specialisation can occur in human adults?

Answer 3

Haematopoiesis (blood cell production).
Wound healing.
Immune responses.
Oogenesis.
Hair growth.

Question 4

What is required of stem cells in order to generate specialised cells?

Answer 4

Proliferation.

Question 5

What are causes of cellular differentiation?

Answer 5

Changes in gene expression patterns.
Change in cellular environments.
Time.
Stem cell division.

Question 6

What are the two types of stem cell division?

Answer 6

Symmetric:
Provide either two stem cells or two differentiated cells.
Asymmetric:
Provides one stem cell and one differentiated cell.

Question 7

What can occur if symmetric stem cell division is uncontrolled?

Answer 7

Can induce tumorigenesis and tissue degeneration.

Question 8

What can occur as a cause of inappropriate Asymmetric stem cell division?

Answer 8

Can disrupt organ morphogenesis.

Question 9

What are the 3 categories of stem cell differentiation?

Answer 9

Totipotent:
Differentiate into any cell type (zygote and blastomeres).
Pluripotent:
Develop into cells from any of the three germ layers.
Multipotent:
Can develop into several different cell types.

Question 10

At what point in the cell cycle does a cell differentiate?

Answer 10

Whilst in G0 (non-dividing phase).

Question 11

What is cell lineage programming?

Answer 11

Refers to the developmental history of a tissue or organ from the fertilised oocyte.

Question 12

What are the 4 types of cell death and do they cause inflammatory response?

Answer 12

Apoptosis, no inflammation.
Aniokis, no inflammation.
Necrosis, inflammation causing.
Autophagy, usually non-inflammatory.

Question 13

What is apoptosis?

Answer 13

Controlled, regulated, programmed cell death.

Question 14

What are the two main pathways of apoptosis?

Answer 14

Extrinsic:
Triggered by signals coming from outside the cell.
Two common ligands that bind to death receptors are FAS and TRAIL.
Intrinsic:
Triggered by stress or damage to cell.

Intrinsic:
BC12 proteins induce release of cytochrome C.
Which promotes formation of apoptosome protein complex.
Triggers initiator caspade.
Triggers executioner caspades.
Causes cascade.
Results in apoptosis.
Extrinsic:
FAS ligands on T-killer lymphocytes bind to FAS death receptor of cell.
Binding triggers same cascades as intrinsic

Question 15

Which cells does anoikis affect and how does this affect cancers?

Answer 15

Anchorage-dependent cells.
Can lead to cancer metastasis.

Question 16

What is anoikis?

Answer 16

Controlled cell death due to loss of cell-ECM interaction.
(ECM = extra cellular matrix).

Question 17

What is necrosis and how do noxious stimuli play a part in it?

Answer 17

Cell death due to acute cellular injury.
Noxious stimuli can include:
Pathogens.
Oxygen deprivation.
Extreme environmental conditions.
All of these cause irreversible injury.

Question 18

How do cells respond to injury during necrosis and how is this induced?

Answer 18

Cells will undergo autolysis.
Induced by excessive cytosolic calcium and reactive oxygen species (ROS).

Question 19

What is autophagy and what is it in response to?

Answer 19

The orderly degradation and recycling of cellular components.
Is in response to cellular starvation.

Question 20

What is the mechanism involved in autophagy and how does it work?

Answer 20

A double membrane vesicle named autophagosome.
Encapsulates cytoplasm, malformed proteins, organelles and pathogens.
Fuses with lysosome for degradation.
Does not always lead to cell death.

Malformed proteins break down into AAs to be recycled.

Question 21

How is apoptosis characterised within the cell?

Answer 21

Characterised by biochemical and physical changes in cell.