KA5: protein control of cell division: control of programmed cell death (apoptosis)

Question 1

what is apoptosis triggered by?

Answer 1

cell death signals that can be external or internal

Question 2

give an example of an external death signal

Answer 2

The production of death signal molecules from lymphocytes

Question 3

give an example of an internal death signal

Answer 3

DNA damage

Question 4

describe how external death signal molecules bring about apoptosis

Answer 4

External death signal molecules:

-bind to a surface receptor protein
-trigger a protein cascade within the cytoplasm

Question 5

what causes the activation of p53 tumour-suppressor protein?

Answer 5

an internal death signal resulting from a DNA damage

Question 6

what do both types of death signal result in?

Answer 6

the activation of caspases (types of protease enzyme) that cause the destruction of the cell

Question 7

explain why apoptosis is essential during development of an organism

Answer 7

to remove cells no longer required as development progresses or during metamorphosis

Question 8

when may cells initiate apoptosis?

Answer 8

in the absence of growth factors