Apoptosis

What is apoptosis?

Programmed cell death

What is an example of apoptosis?

When we develop, webs are formed between fingers, so the skin in between our fingers is programmed to die by apoptosis

What is the hayflick limit?

Cells usually undergo 50 mitosis divisions then undergo an organised death

What does it ensure?

Hydrolysis enzymes are not released into the surrounding environment

What are mitosis and apoptosis essential for?

Shaping organisms

What is the 1st and 2nd step of apoptosis?

1) Enzymes break down cell cytoskeleton

2) Cell surface membrane changes and small blobs form

What is the 3rd and 4th step of apoptosis?

3) Nucleus disintegrates - chromatin condense, nuclear envelope breaks, DNA breaks into fragments

4) Cell breaks up into vesicles

What is the last step of apoptosis?

Taken up by phagocytes and digested

What do cells that control the cell cycle and apoptosis respond to?

maternal cell stimuli and external stimuli

What is an example of response to stimuli?

Cell stress (irreparable genetic damage, RNA decay, cellular injury)

What are external factors?

Stress

What are signalling chemicals?

Include cytokines, hormones and growth factors, nitric oxide, bacteria and viruses, pollutants and UV light

What happens when proteins are released into the cytosol?

Bind to apoptosis inhibitor proteins

What happens with more cell stress?

Poor health of the cell, which means apoptosis is less likely to be receptive to the cell

What does too little and too much apoptosis do?

Too little = tumours form

Too much = cell loss and degeneration (motor neuron disease)