Infection& Response (3)
what are communicable diseases?
a disease caused by a pathogen
what is a pathogen
a micro-organism that causes disease eg. bacteria, viruses, fungi, protists
how do viruses reproduce
by inserting genes into cells which causes them to produce more copies before the cell explodes.
what does bacteria do?
releases toxins into the body to damage cells
what do fungi do
damage cells
what are protists
single celled organisms that cause infection. the animal that may spread them eg mosquitos is called the vector
what are the plant diseases
rose black spot (fungus) causes leaves to fall off
tobacco mosaic virus - discolours leaves, less chlorophyll, stunted growth
what are the viruses you need to know about
measles- cause a rash, spread by droplets
HIV - causes AIDS spread by people sharing needles or bodily fluids
what are the bacteria you need to know about
salmonella : undercooked food- food poisoning
gonorrhoea : std causing yellow discharge
what are protists you need to know
malaria is caused by a protist infecting red blood cells spread by mosquitos (vector)
how does the human body defend itself from disease
- skin acts as a barrier to them entering
- mucus in the nose and trachea traps pathogens
- acid and enzymes in ghe digestive system destroy enzymes
- white blood cells such as lymphocytes produce antitoxins to neutralise toxins made by pathogens and antibodies that bind to the antigen of a pathogen which stop viruses from infecting cells by causing them to clump together
how do white blood cells defend the body from disease/pathogens
white blood cells such as lymphocytes produce antitoxins to neutralise toxins made by pathogens and antibodies that bind to the antigen of a pathogen which stop viruses from infecting cells by causing them to clump together
another type of white blood cell called phagocytes will then ingest and destroy these pathogens
how do antibodies work?
an antigen on a pathogen will have a specific shape, therefore only an antibody that fits it will be able to neutralise it
if pathogens are unknown to the immune system lymphocytes will create all different shapes of antibody until one fits, then once the correct antibody is found , a copy of the antibody and a copy of the antigen are stored in the immune system (immunity)
what are lymphocytes
a type of white blood cell that produces antitoxins to neutralise toxins made by pathogens and antibodies that bind to the antigen of a pathogen
what are phagocytes
a type of white blood cell that ingests pathogens after they've been neutralised
what is a vaccine
an inert version of a virus injected into your body so that you can gain immunity by lymphocytes finding the right antibody for the virus and storing it, without you becoming ill
what are antibiotics
medicines that kill bacteria, not viruses
what are the cons of using antibiotics
- difficult to make them target specific bacteria so to not damage cells or kill "good" bacteria
- a whole course must be taken to kill all bacteria or more resistant bacteria will survive and multiply as they become resistant over time through mutation, so the more u use antibiotics the less effective they become
what is the process of synthetic drug development
- they sre out through trials to test for efficacy, toxicity and dose
- they are tested on cell tissue, animals then humans
- blind trial : test group are given drug , control group are given placebo without being made aware
- double blind trial: even the doctors dont know which is which to eliminate bias
uses of monoclonal antibodies
- combat diseases
- medical diagnosis
- pathogen detection
- identifying molecules : dye is bound to antibodies which attach to specific molecules for example hcg is a hormone found in pregnant womens urine which is used for pregnancy tests
what are monoclonal antibodies
antibodies produced by clones of a cell that produces a desired antibody. this is achieved by injecting an animal with an antigen then binding lymphocytes from an animal (typically mouse that has created the desired antibodies as a response to the antigen) with myeloma cells (tumour cells) to create a hybridoma. hybridoma multiply, producing lots of the same antibody