Cell Recognition And The Immune System Flashcards
Non-specific - Phagocytosis (3)
- Phagosome/vesicle fuses with lysosome;
- (pathogen) destroyed by lysozymes/hydrolytic enzymes;
- Antigen (from pathogen) displayed on cell membrane (of phagocyte/antigen presenting cell);
Non-specific - Describe how a phagocyte
destroys a pathogen present in the
blood.(3)
- Engulfs;
Accept endocytosis
OR
Description
Ignore ‘taken in’ - Forming vesicle/phagosome and fuses with lysosome;
- Enzymes digest/hydrolyse;
Specific - Describe how presentation of
a virus antigen leads to the secretion of
an antibody against this virus antigen.
- Helper T cell / TH cell binds to the antigen (on the antigen-presenting cell / phagocyte);
- This helper T / TH cell stimulates a specific B cell;
- B cell clones
OR
B cell divides by mitosis; - (Forms) plasma cells that release antibodies;
Specific - What is antigen? (2)
- Foreign protein;
- (that) stimulates an immune response/production of antibody
Specific - What is antibody? (2)
- A protein/immunoglobulin specific to an antigen;
- Produced by B cells OR Secreted by plasma cells;
Specific - Antibody specificity (4)
- Antibody has (specific) tertiary structure
- Has binding site/ variable region which only binds to one antigen
- Antigen is only found on this particular (pathogen/cell/tissue)
- so antibody (only) binds to / forms antigen/antibody complex with these (pathogen/cell/tissue) destroying them
Specific - Antigen-Antibody
complex formation (4)
- Antibody has 4 polypeptide chains and has a quaternary structure
- Antibody has a variable region which has a specific amino acid sequence/primary structure
- Shape of the binding site is complementary to the antigen
- Forming an antigen-antibody complex
Specific - Humoral Response (6)
- Antigen on surface of bacterium binds to surface protein / surface receptor on a (specific/single) B cell;
- (Activated) B cell divides by mitosis / produces clone;
- (Division) stimulated by cytokines / by T cells;
- B cells/plasma cells release antibodies;
- (Some) B cells become memory cells;
- Memory cells produce plasma / antibodies faster;
Specific - Give two types of cell, other
than pathogens, that can stimulate an
immune response.(2)
- (Cells from) other organisms/transplants;
- Abnormal/cancer/tumour (cells);
- (Cells) infected by virus;
- Antigen presenting cells
Specific - Draw a labelled diagram of an
antibody (3)
- Y shape showing two long and two short (polypeptide) chains correctly positioned;
- binding site labelled on the end of the branches of the Y of the antibody;
Accept one or two being labelled, if two both must be correct. - Variable region labelled /Constant region labelled / Disulfide bridge/bond labelled;
Specific - Describe and explain the role
of antibodies in stimulating
phagocytosis.
Do not include details about the
process of phagocytosis.
- Bind to antigen
OR
Are markers;
Accept opsonin for ‘marker’
Accept form (antibody-antigen) complexes/are complementary to antigen - (Antibodies) cause clumping/agglutination
OR
Attract phagocytes;
Vaccines - Immunity – Compare Active and
Passive Immunity (6)
- Active involves memory cells, passive does not;
- Active involves production of antibody by plasma cells/memory cells;
- Passive involves antibody introduced into body from outside/named source;
- Active long term, because antibody produced in response to antigen;
- Passive short term, because antibody (given) is broken down;
- Active (can) take time to develop/work, passive fast acting;
Vaccines - Immunity – Compare Primary
and Secondary Response (4)
- Before vaccination no antibody released because patients not yet encountered vaccine/antigen/virus;
- Primary response/after first dose) activation/clonal selection/expansion of B cells into plasma cells;
- Plasma cells release antibodies;
- Secondary response/after second dose) memory cells produce more antibodies/produce antibodies more
quickly;
Vaccines - How a vaccine
produces an immune response (7)
- Vaccine contains antigen from pathogen;
- Macrophage presents antigen on its surface;
- T cell with complementary receptor protein binds to antigen;
- T cell stimulates B cell;
- (With) complementary antibody on its surface;
- B cell/plasma cell secretes large amounts of antibody;
- B cell divides to form clone all secreting/producing same antibody;
Vaccines - Explain why giving children
more than one vaccination develops
good immunity (2)
- (Production of more) memory cells;
- (So) higher concentration of (circulating) antibodies in blood
OR
(So) rapid production of antibodies (on further infection)