AH Biology - Unit 1 - KA5(d) - Control of Programmed Cell Death (Apoptosis)

What is apoptosis triggered by?

Apoptosis is triggered by external or internal cell death signals. External cell death signals are the production of cell death signal by a lymphocyte. Internal cell death signals is DNA damage.

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What do external death signal molecules bind to, and what does this trigger?

External death signal molecules bind to surface receptor molecules bind to surface receptor proteins and trigger a protein cascade of caspases within the cytoplasm.

What do internal death signals resulting from DNA damage cause?

Internal death signals resulting from DNA damage cause the activation of the P53 tumour-supressor protein.

What do both external and internal death signals result in?

Both external and internal death signals result in the activation of caspase enzymes (protease enzymes) that cause the destruction of the cell.

What does apoptosis remove?

Apoptosis removes healthy cells during the development of an organism where the cells are no longer required as cell development progresses. For example, finger formation, or tadpoles losing their tails during metamorphosis.

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Cells may also initiate apoptosis in the absence of what?

Cells may also initiate apoptosis in the absence of growth factors.