3.2.4 Cell recognition and the immune system

Question 1

What happens after an APC has formed?

Answer 1

• Antigens are presented by an antigen presenting cell.

• Helper T cells with complimentary receptors bind to the antigen.

• Helper T cell is activated and undergoes mass mitosis.

• Forming cytotoxic T cells and more Helper T cells.

• Cytotoxic T cells produce perforin to kill cells and make holes in their cell surface membrane.

• Water enters the cell causing it to burst.

• It only works on whole cells.

Question 2

What is an antigen?

Answer 2

• An antigen is a protein/glycoprotein.

• That stimulates an immune response/the realise of a specific antibody.

Question 3

What is agglutination?

Answer 3

When one antibody binds to 2 pathogens causing them to clump together.

This makes pathogens more easily engulfed by phagocytosis.

Question 4

What is neutralisation?

Answer 4

Antibodies can act as antitoxins, being with toxins secreted by pathogens

This makes them harmless

Question 5

Describe humoral immunity

Answer 5

T helper cells bind to complimentary antigens presented by a specific B cell. This is clonal selection.

T helper cells activate the B cells.

The B cells rapidly divide by mitosis to produce plasma and memory B cells.

This is clonal expansion.

The plasma cells produce specific complimentary antibodies that will bind to the pathogen and lead to it being destroyed by phagocytosis.