Immunology Flashcards
Describe the non-specific defence mechanisms the body may launch against pathogens (5)
PHAGOCYTOSIS
1. Pathogen is engulfed by phagocyte
2. Engulfed pathogen enters cytoplasm of phagocyte in vesicle
3. Lysosome fuse with vesicle, releasing digestive/hydrolytic enzymes
4. Lysosome enzymes break down pathogen
5. Waste materials ejected from cell by exocytosis
Describe how a phagocyte destroys a pathogen present in the blood (3)
- Phagocyte engulfs the pathogen
- Forming vesicle / phagosome and fuses with lysosome
- Enzymes digest / hydrolyse
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
Explain how the humoral response leads to immunity (3)
- B cells specific to 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 (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 cell
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
Describe the difference between active and passive immunity (4)
- Active involves memory cells whereas passive doesn’t involve memory cells
- Active involves production of antibody by plasma/ memory cells
- Passive involves antibody introduced into body from outside
- Active is long term because antibody is produced in response to antigen
- Passive is short term because antibody is broken down
- Active can take time to develop/work whereas passive is fast acting
When a vaccine is given to a person, it leads to the production of antibodies against a disease causing organism. Explain how. (5)
- Vaccine contains antigen from pathogen
- Macrophage presents antigen on its surface
- Specific T (helper) cell with complementary receptor protein binds to complementary antigen
- T helper cell stimulates specific B cell
- With complementary antibody on its surface
- B cell divides by mitosis to form plasma cells
- Plasma cells secrete large amounts of antibodies
State why some antibodies are referred to as monoclonal (1)
Antibodies produced from a single clone of Plasma / B 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. (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 the structure of the human immunodeficiency virus (HIV). (5)
- HIV RNA (as genetic material)
- Reverse transcriptase
- HIV capsid
- HIV viral lipid envelope
- Attachment protein (HIV glycoprotein)
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