Apoptosis And Necrosisi

Question 1

Why is cell death important?

Answer 1

• embryogenesis and foetal development
• cell is damaged beyond repair
• cell is infected with a virus can prevent viral spread
• removal of ineffective or potentially damaging immature B or T cells
• control of malignant cells

Question 2

What is necrosis?

Answer 2

Uncontrolled cell death associated with disease

Question 3

What is apoptosis ?

Answer 3

Programmed cell death or suicide
Essential part of normal health

Question 4

Importance of apoptosis

Answer 4

Embryo development
Immune system - destroying self resulting immune cells and viral infected cells
Homeostasis- counter balance to cell division
Cancer- radiotherapy and most chemotherapy drugs work by apoptosis

Question 5

How is apoptosis triggered

Answer 5

Two main pathways for triggering apoptosis:
1) receptor mediated (extrinsic pathways)
2) mitochondria mediated ( intrinsic pathways)

Question 6

Stages of apoptosis

Answer 6

When a healthy cell receives a death signal it becomes committed to die but this process is reversible
If not reversed they undergo execution which is irreversible, the cell is dying and becomes condensed
Apoptotic bodies ready to engulf by macrophages and neighbouring cells

Question 7

What are caspases and what are their function ?

Answer 7

Caspases- cysteine aspartic proteases
A family of 12 proteases that exist as inactive pro enzymes in cells
Following activation by cleavage’ they can activate other caspases in a cascade
Two types of caspases: initiator caspases and effector caspases

Question 8

What activates an intrinsic pathway?

Answer 8

The intrinsic pathway can be activated by a variety of cell stresses such as free radical damage, DNA damage , viral infection or absence of survival signals

Question 9

What is the role of mitochondria in the intrinsic pathway

Answer 9

Cytochrome c is located in the inner mitochondrial membrane and is an essential component of the electron transport chain
In the intrinsic apoptosis pathway pores form in the outer mitochondrial membrane allowing release of cytochrome c into the cytosol

Question 10

Discuss necrosis

Answer 10

It’s primarily driven by external extrinsic factors
Example : infection, direct toxic threat, freezing, trauma etc