[5.1-2] defence mechanisms and phagocytosis Flashcards
1
Q
what will proteins embedded in the cell membrane act as a mechanism for?
A
- identifying cells as ‘self’, rather than ‘non-self’
- this is the basis of the immune response (recognition system)
2
Q
how does the immune system recognise the proteins?
A
because they have a specific tertiary structure
3
Q
what is an immune response triggered by?
A
the presence of a ‘non-self material’ eg.
- pathogens (bacteria, viruses)
- human cells from another individual
- tumour cells
- toxic molecules from pathogens
- these will all be covered in proteins that will act as ‘non-antigens’
4
Q
what is the 5 step process of phagocytosis?
A
- bacteria engulfed due to membrane fluidity of phospholipid bilayer
- bacterium now contained in a ‘phagosome’
- lysosomes fuse with phagosome to form a ‘phagolysosome’
- therefore, lysozymes can hydrolyse bacterial molecules
- the hydrolysis products of the bacterium are absorbed by the phagocyte
5
Q
what are some examples of products of bacterial digestion?
A
- amino acids
- nucleic acids
- monosaccharides
- fatty acids / glycerol
BUT bacterial antigens are often retained intact by the phagocyte
6
Q
what is an antigen?
A
any part of an organism or substance that is recognised as non-self (foreign) by the immune system and stimulates an immune response