Viruses & Dat Flashcards
Explain how an ELISA test works
1) Antibodies to PSA placed in test plate
2) Blood from patient added. PSA will bind to antibody if present. Wash plate remove unbound antigens.
3) Antibody with enzyme attached added which will only bind to first antibody if PSA present. Wash plate
4) Colourless substrate added
5) Enzymes converts colourless substrate to coloured if enzyme present, hence, if PSA is present
Explain How Agglutination works
Each antibody has 2 binding sites. Each antibody binds to an antigen on a different pathogen to make a lattice like structure of antigen-antibody complex. This immobilises the pathogen and render a toxin harmless and makes it easier to engulf and destroy the pathogens during phagocytosis
Explain how the Cellular Response works
T cells become activated when antigen is being displayed on surface of own body cells (A.P.C) after phagocytosis. T helper cell with comp. Shaped receptor is activated and releases chemicals which stimulates:
Cytotoxic cells to divide by mitosis which destroy infected body cells which show the antigen on the surface
T memory cells will stay for secondary response if same antigen encountered
More helper T cells to stimulate B cells to produce antibodies in Humoral Response
Explain how the Humoral Response works
B cell with the receptor of comp. Shape to the antigen will become activated (stimulated from chemicals from T helper Cells). Activated B cell divide mitosis to produce genetically identical cells by clonal selection.
Some are Plasma Cells that secrete antibodies called monoclonal antibodies
A few are memory cells which don’t produce antibodies and remain for secondary response.
Antibodies produced bind to the antigen forming antigen - antibody complex and destroy antigen by agglutination
What are monoclonal antibodies?
A large No. Of one type of antibody produced by a clone of plasma cells
What are the uses of Monoclonal antibodies?
Targeting Medication : A therapeutic drug can be attached to the antibody and as the antibody will only bind to a specific antigen, the drug will be carried directly to specific cells for the drug to work on
medical diagnosis - ELISA test
Give 2 ways in which pathogens cause disease agent entering the body of their host?
They produce toxins
Damage the cells and tissues
What is an antigen?
A molecule that triggers an immune response leading to antibody production
Define pathogen
An organisms that causes disease in another organism e.g. Bacteria/Fungi/Viruses
What are the methods the body uses to prevent the entry of pathogens?
- Mucus- Stomach acid- Enzymes
How are pathogens able to cause disease?
Release toxins
What do pathogens do?
- Destroy host cells- Produce toxins
What are antibodies?
Proteins that bind to antigens to kill pathogens
What is the structure of an antibody?
- Antibodies are proteins with a specific primary, secondary and tertiary structure- Antibodies have a variable region and a constant region which are joined by a hinge and held together by disulphide bridges- The antibodies tertiary structure is responsible for the specific variable region which allows the antibody to form antibody-antigen complexes with its complementary antigen
What happens in a secondary immune response?
- The same pathogen with the same antigen infects you- The immune response is faster and stronger because you already have the memory B and T-cells which can divide and carry out the humeral and cellular responses in order to kill pathogens (T) and produce antibodies (B) - Because the pathogen has less time to replicate you feel no symptoms - Antigenic variation and various pathogen strains can prevent this
What is a vaccine?
It contains antigens from a dead/weakened pathogen which stimulate the immune response to produce antibodies/plasma cells/memory cells
What is antigenic variability?
The ability of a pathogen to change the antigens on its surface so the antibodies produced by your memory B-cells are no longer complimentary are upon reinfection you have to go through the primary immune response
What is active immunity?
When you produce your own antibodies
What is passive immunity?
When you are given antibodies by another organism
Give an example of natural active immunity
You get infected by a pathogen and undergo a primary immune response
Give an example of artificial active immunity
You receive a vaccine and undergo a primary immune response
Give an example of natural passive immunity?
You are given antibodies by your mother either in breast milk or the placenta
Give an example of artificial passive immunity?
You receive someone else antibodies through a blood transfusion
Compare active and passive immunity
Active:- Slow- Long term- Make memory cells- Exposed to antigen
Passive:- Fast - Short term (foreign antibodies are broken down by the body) - No memory cells- Not exposed to antigen
What does HIV do?
Infects helper T-cells weakening immune system which leads to the development of AIDS
How can people die from HIV?
HIV doesn’t directly kill you, your immune system becomes so weak it cannot fight any pathogens and you usually die from pneumonia/TB
How does HIV replicate
- Virus attachment protein binds to a receptor on the TH-cell- Reverse transcriptase makes double stranded DNA from the viruses RNA- DNA enters the nucleus through the nuclear pore- TH-cell makes more copies of the viruses RNA and reverse transcriptase - Capsid reforms- Virus (RNA and reverse transcriptase) leaves host cell and takes an envelope from hosts membrane
State the ethical issues for vaccines
Testing on Animals
Animal based substances
Risk on Human testing
