structure and function of antibody
They are proteins produced by the immune system in response to foreign substances
What are antigens
Molecules that can generate an immune response when detected by the body
What is the difference between active and passive immunity?
Active immunity is when your immune system makes its own antibodies after being stimulated by an antigen.
Passive immunity is immunity that you get from being given antibodies made from a different organism
What is herd immunity?
This is where those not vaccinated individuals are less likely to catch the disease as more people are vaccinated so less likely to spread
What is the function of helper T cells?
- release chemical signals that activate and stimulate phagocytes and cytotoxic t cells
- activate B cells
What is antigenic variation?
Different antigens are formed due to changes in the gene of a pathogen, so their surface changes which means the memory cells will no longer recognise
What happens in phagocytosis?
- A phagocyte recognises foreign antigens on a pathogen
- Phagocyte’s cytoplasm engulfs pathogen
- Pathogen contained in a phagocytic vacuole in cytoplasm of phagocyte
- Lysosome fuses with vacuole and releases lysozyme which break down the pathogen
- Phagocyte presents pathogens antigens to act as an antigen-presenting cell
what are monoclonal antibodies?
antibodies that are specific to the antigen prodiced from identical B cells
Explain why you can become ill with the flu even if you have been infected by the influenza virus before?
- the antigens on the surface of the influenza virus changes regularly
- memory cells produced will not recognise other strains with different antigens
- so no atobidies to produced quick enough so you fall ill
- vaccine has to change every year
What disease does hiv lead to?
It leads to AIDS where the immune system deteriorates and is more susceptible to diseases so it eventually fails
What is the difference between the cellular and humoral response?
The cellular response involves the activation eg T Cells
The humoral response is specific and focuses on immunity eg B cells, clonal selection, monoclonal antibodies
What do antigens allow the immune system to identify ?
Pathogens
Abnormal body cells
Toxins
Cells from other individuals of the same species
How does HIV replicate?
- The attachment protein attaches to a receptor molecule on the cell membrane of the host helper T-cell
- The capsid is released into the cell, uncoats and releases genetic material (RNA) into cell cytoplasm
- Reverse transcriptase is used to make a complementary strand of dna from viral RNA template
- Double stranded DNA is made and inserted into human DNA
- Host cell enzymes make the viral proteins from viral DNA found within human DNA
- Viral proteins are assembled into new viruses which bud from the cell and go infect other cells
What are B cells?
- Covered with antbodies that bind to antigens : CLONAL SELECTION
- Activated b cells divide into plasma cells that secrete antibodies
What does HIV look like?
Capsid
Attachment protein
Rna
Reverse transcriptase
What are the ethical reasons regarding the use of vaccines?
animal testing
risk of side effects on humans when testing
decisions who gets vaccine first
Differences between primary and secondary response
- The primary response happens the first time an pathogen invades whereas a secondary response happens the second time
- The primary response is slow v secondary is fast
- The primary response leads to the persons showing symptoms as antibodies not produced
- The secondary response produced memory cells quicker and B cells divide into plasma quicker
What is the difference between the direct and indirect elisa test?
- In a direct Elisa you are detecting the presence of an antigen and the primary antibody used is the enzyme linked antibody.
- In an indirect Elisa you are detecting the antibody, and the secondary antibody is enzyme linked.
How does vaccination lead to immunity
Vaccines contain dead or attentuated from or pathogen
Antigens will produce the memory cell
What is HIV?
Human immunodeficiency virus that affects the immune system
What are the types of active immunity?
Natural - immune after cathcing a disease
Artificial - vaccine
What are the types of passive immnity?
Natural - baby becomes immune through breast milk or placenta
Artificial - immune after being injected with antibodies from someone else
What are the steps for the elisa test?
- Antigen bound to bottom of well plate
- Antibodies added and any specific to antigen will bind and those not specific will be washed out
- Secondary antibody with an enzyme attached and will bind to primary antibody, and the unbound ones will be washed out
- Solution is added to the well, which contains a substrate that can react with the enzyme attached to second antibody and produce a coloured product indicating the patient has the pathogen
