Introduction to pathogens, allergens and antigens Flashcards
What are self proteins called?
Major Histocompatibility Complex I (MHC I).
What are antigens ?
Any set of molecules that activate the immune system are called antigens.
What are the types of antigens ?
Self-antigens (self markers)
Non-self antigens
Allergens
What are non self antigens ?
molecules that are not found on self cells.
What are self antigens ?
located on the surface of cells, they mark the cells of an organism as ‘self’ so that the immune system doesn’t attack them. In humans, the most important self-antigens take the form of major histocompatibility complex (MHC) proteins, which can be divided into two different classes:
MHCI
MHCII
What are MHCI proteins ?
expressed on all nucleated cells in the body. Therefore, virtually all cells in the human body except for those without a nucleus (e.g. red blood cells) express MHC I proteins.
What are MHCII proteins ?
found on specialized cells of the immune system.
Malfunctions involving self antigens/self-markers
self cells that set off the immune system.
What are allergens ?
molecules found on non dangerous particles that set off the immune system.
What is a disease?
Any change that impairs the function of an individual in some way.
What is an infectious disease?
A disease caused by a pathogen.
What is a pathogen ?
an agent able to cause disease in a host.
What is an infection ?
When the pathogen is present in/on the host.
What does sterile mean ?
Free of pathogens
Non cellular agents - prions
There are two forms of prions ( PrP - sen which is normal and PrP - Sc which causes disease. They are proteins that can be infectious through consumption. They can reproduce on their own. Both proteins have exactly the same primary structure but have a different tertiary structure. Prions cannot be destroyed easily.
Non cellular agents - viruses
Obligate intracellular parasites, they must infect a host before they can reproduce, viruses are the smallest reproducing things. They consist of a protein coat surrounding the DNA or RNA . They cannot make copies without a host cell. Most viruses are host specific ( only infect one type of host )
How do viruses replicate?
- Attachment
- Penetration
- Biosynthesis of components
- Reassembly and lysis
Cellular agents - Prokaryotic bacterial cells . examples
- Gram positive cocci
- E . Coli
- Compylobacter
- Staphyloccus aureus
- Borrelia burqdorferi
How can bacteria be identified?
They can be identified according to their shape
What is a plasmid and it’s significance?
Plasmids are small circular molecules of DNA. Plasmids can pass between bacterial cells . This is how they pass on antibiotic resistance
How do bacteria enter humans ?
- body contact
- sexual contact
- food and water
- droplets / airborne
- carrying vector
- injecting vector
How do bacteria reproduce?
Binary Fission
Treatment for bacterial infection
Antibiotic
What is an antibiotic?
A chemical compound extracted from fungi or bacteria that can be used against a disease agent. Bacteria can be resistant to some antibiotics
What is a broad spectrum antibiotic?
Acts on many types of bacteria
What is a narrow spectrum antibiotic?
Only inhibit a few types of bacteria
Fungi
Eukaryotes that secrete digestive enzymes into their environment. Single celled fungi have a nucleus and cell walls that contain antigens
Protozoans
Single celled eukaryotes ( e.g. malaria )
