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. Waste 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) same species but different organisms ;
- Abnormal/cancer/tumour (cells);
When a vaccine is given to a
person, it leads to the production of antibodies against a disease-causing organism. Describe how
- Vaccine contains attenuated form antigen from pathogen;
- Macrophage presents antigen on its surface;
- T (helper) cell with complementary protein receptor 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; VS. Active involves production of antibody by plasma cells/memory cells;
- Passive involves antibody introduced into body from outside/named source;
VS . Active-long term, because antibody produced in response to antigen; - Passive short term, because antibody (given) is broken down;
VS. 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;
- (Specific) tertiary / 3D structure / shape;
- (So) Only binds to / fits / complementary to one antigen;
Describe the structure of the human immunodeficiency virus (HIV).
- RNA (as genetic material);
- Reverse transcriptase;
- (Protein) capsomeres/capsid;
- (Phospho)lipid (viral) envelope OR Envelope made of membrane;
- Attachment proteins;
Describe the role of antibodies in producing a positive result in an ELISA test.
- (First) antibody binds/attaches /complementary (in shape) to antigen; 2. (Second) antibody with enzyme attached is added;
- (Second) antibody attaches to antigen;
- Substrate added and colour changes;
Describe how a person infected with HIV will develop AIDS (if untreated) and die of secondary infections.
- leads to increased destruction of helper
- Less activation of B cells
- Less production of plasma cells/antibodies OR (With cytotoxic T cells) less able to kill virus infected cells;
- (less able to) destroy other microbes/pathogens OR (less able to) destroy mutated/cancer cells;
What is an antigen
Foreign protein;
Accept glycoprotein / glycolipid / polysaccharide
- (that) stimulates an immune response / production of antibody
What is an antibody?
A protein / immunoglobulin specific to an antigen;
2. Produced by B cells
OR
Secreted by plasma cells;
describe the cellulose / cell mediated response
1) Phagocyte engulfs pathogen and presents the antigen on the cell surface membrane.
2) TH cell with specific protein receptor molecule binds to presented antigen
3) Once TH cell binds to the presented antigen it is activated. It then rapidly clones by mitosis.
