Unit 3 - Infection & Response Flashcards
What is a pathogen?
A micro-organism that causes disease.
What are the pathogens?
-Bacteria
-Protists
-Fungi
-Viruses
How do viruses reproduce and what is an example of one?
Inserting genes into cells which causes them to produce more copies. HIV is an example (it is an STI) which can causes AIDS, leading to a compromised immune system. Can also be spread by needle sharing. Another example is measles, which is spread by droplets and causes a rash.
How do bacteria cause illness and what is an example?
They release toxins into your body that damage cells. An example is salmonella in undercooked food, or gonorrhoea, an STI which causes yellow discharge.
How do protists (and fungi) damage cells?
Fungi work similarly to bacteria in that they damage cells. Protists are single-celled organisms, such as malaria which is caused by a protist and infects red blood cells. Mosquitoes are the vector.
What are some examples of plant diseases?
Rose black spot (fungus) - causes black spots on leaves which eventually cause the leaf to fall off.
Tobacco mosaic virus (TMV) - discolours leaves as a result of inhibiting chlorophyll production, which stunts growth
What are our bodies’ defences against disease?
Skin - physical barrier
Mucus in nose/trachea - traps pathogen
Acid/enzymes in digestive system - kill pathogens
What are plants’ defences?
-cell wall, waxy cuticle and bark act as barriers
-Antibacterial chemicals
-Poison/thorns to deter organisms
How do lymphocytes (white blood cells) work?
Produce antitoxins to neutralise toxins made by pathogens, and antibodies that bind to the antigen of a pathogen (only if they fit.) This stops viruses infecting cells and causing them to clump together
How do phagocytes (white blood cells) work?
Ingest pathogens, killing them
How do memory lymphocytes work?
Lymphocytes that produce antibodies which fit a certain pathogen (antigen) are stored in lymph nodes, ready for the next time the pathogen enters the body, granting immunity.
How do vaccines work?
Introducing a dead/inert version of a virus into your body, so you produce lymphocytes specific to that pathogen and gain immunity, all without falling ill.
What to antibiotics do?
Kill bacteria, not viruses. They must target specific bacteria and not damage our cells or other ‘good’ bacteria. The whole course must be taken to kill all bacteria, or more resistant bacteria will survive and multiply
Where does aspirin come from?
Bark of a willow tree
Where does penicillin come from?
Mould
Where does digitalis come from?
Foxglove plants
Why do drugs go through clinical trials?
To assess:
-Efficacy
-Toxicity
-Dosage
What are the stages of clinical testing?
1 - lab trials on cell tissue
2 - trials on animals
3 - trials on healthy humans
4 - trials on infected humans
What is a blind trial?
Where a test group are given a drug while a control group are given a placebo without being made aware.
What is a double blind trial?
Where the doctors do not know which group is the test group and which is the control group in order to eliminate bias
How do we produce monoclonal antibodies?
They are produced from clones of a cell that produces a desired antibody. We do this by combining lymphocytes from mice with tumour cells to make a hybridoma. The hybridoma cells then multiply, producing lots of the same antibody to treat a patient
What do we use monoclonal antibodies for?
-Combat disease
-Medical diagnosis
-Pathogen detection
-Identifying molecules, as a dye is bound to antibodies, which attach to specific molecules e.g. HCG, a hormone found in pregnant women’s urine used for pregnancy tests
What are the downsides of monoclonal antibodies?
Side effects, such as allergic reactions, are worse than expected
