immunology Flashcards
describe the non-specific defence mechanisms the body may launch against pathogens (5 marks)
the process is called phagocytosis – No Mark
1. pathogen is engulfed by the phagocyte
2. engulfed pathogen enters the cytoplasm of
the phagocyte in a vesicle
3. lysosomes fuse with vesicle releasing
digestive enzymes
4. lysosome enzymes break down the pathogen.
5. qaste materials are ejected from the cell by exocytosis
describe how a phagocyte destroys a pathogen present in the blood
- engulfs
- forming vesicle/phagosome and fuses with lysosome
- enzymes digest/hydrolyse
give two types of cell, other than pathogens, that can stimulate an immune response
- (cells from) other organisms/transplants
- abnormal/cancer/tumour (cells)
- (cells) infected by virus
when a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism
describe how
- vaccine contains antigen from pathogen
- macrophage presents antigen on its surface
- T (helper) cell with complementary receptor protein binds to antigen
- T cell stimulates B cell
- (with) complementary antibody on its surface
- B cell divides to form clone secreting / producing same antibody
- B cell secretes large amounts of antibody
explain how the humoral response leads to immunity
B cells specific to the antigen reproduce by mitosis
B cells produce plasma and memory cells
second infection produces antibodies in larger quantities AND quicker
describe and explain the role of antibodies in stimulating phagocytosis
bind to antigen OR are markers
(antibodies) cause clumping/agglutination OR attract phagocytes
describe the difference between active and passive immunity
- 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
state why some antibodies are referred to as monoclonal
(antibodies) produced from a single clone of B cells / plasma cells
OR
(antibodies) produced from the same B cell / plasma cell
tests using monoclonal antibodies are specific
use your knowledge of protein structure to explain why
(specific) primary structure / order of amino acids
(apecific) tertiary / 3D structure / shape
(So) only binds to / fits / complementary to one antigen
describe the structure of the human immunodeficiency virus (HIV)
- HIV RNA (as genetic material)
- reverse transcriptase
- (protein) capsomeres/capsid (HIV)
- (phospho)lipid (viral) envelope OR Envelope made of membrane
- attachment proteins (HIV glycoprotein)
describe how a person infected with HIV will develop AIDS (if untreated) and die of secondary infections
high viral load leads to increased destruction of helper T/CD4 cells
less activation of B cells/cytotoxic T cells/phagocytes
less production of plasma cells/antibodies OR (With cytotoxic T cells) less able to kill virus infected cells
(more able to) destroy other microbes/pathogens OR (more able to) destroy mutated/cancer cells
describe the role of antibodies in producing a positive result in an ELISA test
- (first) antibody binds/attaches /complementary (in shape) to antigen
- (second) antibody with enzyme attached is added
- (second) antibody attaches to antigen
- (substrate/solution added) and colour changes
Describe and explain the role of antibodies in stimulating phagocytosis (2)
- Bind to antigen
- (Antibodies) cause clumping/agglutination
OR attract phagocytes
What is the role of T Helper cells? (3)
- Specific T helper cell binds to antigen presenting cell
- Release cytokines that attract phagocytes
- Release cytokines that activate Cytotoxic
Killer T cell - Activates specifically complementary B cell
- Forms memory T helper cells
What is the role of Cytotoxic Killer T cell’s (TC)? (3)
- Locate and destroy infected body cells that present correct antigen
- Bind to antigen presenting cell
- Release perforin, creating holes in cell surface membrane which destroys antigen presenting cel
Explain how antibodies assist in the destruction of pathogens? (4)
- Agglutination
- Specific antibodies bind to antigen on pathogen and clump them together
- Opsonisation
- Marking pathogens so phagocytes recognise and destroy pathogen efficiently
Tests using monoclonal antibodies are specific. Use your knowledge of protein structure to explain why. (3)
- (Specific) primary structure / order of amino acids
- (Specific) tertiary structure / 3D structure / shape
- (So) Only binds / complementary to one antigen
Give 3 uses of monoclonal antibodies
- Immuno Assays (pregnancy test)
- Diagnosis
- Targeting Drugs
- Research
- Killing specific cells
- Isolating specific chemicals
Describe HIV replication (4)
- HIV RNA converted into DNA using reverse transcriptase
- DNA inserted into T helper cell
- DNA transcribed into HIV mRNA
- HIV mRNA translated into new viral proteins
Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus pathogen. (3)
- T helper cell binds to antigen
- T helper cell stimulates specific B cell
- B cell divides by mitosis
- Forms plasma cells that release antibodies
What is an antigen? (2)
- Foreign protein
- that stimulates an immune response / production of an antibody
What is an antibody? (2)
- A protein specific to an antigen
- Produced by B cells
OR - Secreted by plasma cells
What is a monoclonal antibody? (1)
Antibodies with same tertiary structure
OR
Antibodies produced from identical plasma / B cells
