Immunology and disease Flashcards
What is a pathogen?
A microorganism that causes (communicable) disease.
What are the four types of pathogen?
Bacteria Fungi Viruses Protoctista
What is the structure of a virus.
*Acellular - non living
*20-300nm (smaller than bacteria)
*Contain nucleic acids (DNA/RNA) in protein called capsid
*Has either a lipid envelope (HIV) or attachment proteins.
Why does a high mutation rate make it difficult to develop a vaccine?
*mutation leads to antigens change.
*vaccine contains specific antigen.
*antibodies not complementary to antigen.
What is the immune response to a virus that leads to antibody production?
*The virus antigen presented on surface of B cell.
*Th Cell binds + stimulates B cell to make clones - plasma cells.
*Plasma cells secrete antibodies that are complementary to virus antigen so bind to it - killing it.
*Memory cells produced.
How is a pathogen destroyed by phagocytosis.
*Phagocyte recognises foreign antigens.
*Pathogen is engulfed and enclosed in phagosome.
*Vacuole fuses with lysosome - lysozymes released.
*Pathogen hydrolysed.
Why are antibodies only effective against a specific pathogen?
Antigens specific shape/tertiary structure. Antigen will only bind to antibody it’s complementary to. Antigen-antibody complex forms.
What is an antigen?
A glycoprotein molecule on the surface of an organism recognised as non-self by the immune system. So stimulates an immune response.
What is an antibody?
Proteins secreted by plasma cells that have binding sites that are specific to a specific antigen - which they then form an antigen-antibody complex with.
Why do whole cell vaccines produce a greater range of antibodies in organisms?
Because they contain a greater range of antigens - and each antigen stimulates its own immune response.
Two ways in which a pathogen may cause disease once it has entered the body:
*Produce Toxins
*Damage Cells
Use knowledge of protein structure to explain why tests using monoclonal antibodies are specific:
*Specific order of AA (amino acids).
*Specific tertiary structure.
*Only complementary and binds to one antigen.
What is a monoclonal antibody?
Antibodies with the same tertiary structure from the same plasma cell.
How does the ELISA Test work to show a positive result?
*Antibody binds to complementary antigen.
*2nd antibody with enzyme attached added.
*2nd antibody attaches to antigen/first antibody.
*Substrate added and binds to enzyme resulting in colour change.
How is HIV replicated?
*attachment proteins on the HIV bind to receptors on T-cell.
*Virus RNA enters host T cell.
*reverse transcriptase converts RNA to DNA.
*Viral proteins produced (after DNA is transcribed into HIV mRNA) and assembled to produce viral particles.
*lyse out of cell
