Apoptosis

Question 1

What are caspases?

Answer 1

Caspases are a group of degredation enzymes which are responsible for the controlled cell death. If they are overactive, neurodegenerative diseases may occur, and if they are uneractive tumours can form.

Question 2

Describe the entrinsic pathway.

Answer 2

This is where the cell-death signals orginate outside of the targeted cell. It may be the result of a cell infected with a virus showing parts of foreign antigens. The death signal ligand binds to the receptor protein and this causes a change in conformation at the cytoplasmic side. This triggers a signal transduction and activates a protein cascade that produces caspases.

Question 3

Describe the intrinsic pathway.

Answer 3

This is where the death signals originate inside the cell It may be due to DNA damage which would result in the presence of p53 protein which then activates a caspase cascade. This caspase cascade is achieved through disruption of the mitochondria.

Question 4

Describe the caspase cascade in detail.

Answer 4

• The caspase cascade involves a series of post-translational modifications to proteins that are already present in the cytoplasm. This allows a rapid response to occur.
• The caspase cascade involves inactive caspases becoming activated.
• Each initiator caspase activates several executioner caspases which act as DNAase, proteinases and enzymes that destroy keraton and actin filaments.

Question 5

What happens to the broken up cell?

Answer 5

The cell breaks into many small vesicle fragments which are engulfed and injested by phagocytes.