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Only visible under the microscope Include bacteria, fungi & viruses
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1. Nutrient broth poured into flask 2. Neck of flask heated and pulled into an S shape 3. Broth boiled for a few minutes to kill any microbes present and drive out air 4. Broth allowed to cool. It stayed clear and fresh for months. 5. Neck of flask broken off without touching it with hands. Broth went bad within a few days. It became cloudy and was soon teeming with microbes.
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MicrobeDisease VIRUSHIV leading to AIDS Measles Rubella Mumps Colds & Flu Polio BACTERIUMSalmonella food poisoning Gonorrhoea Tuberculosis Chlamydia FUNGUSAthletes Foot
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AIDS: HIV virus Protein coat Genetic material
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Stops immune system working. cancers pneumonia
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Spread & prevention
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Anti-viral drugs help to control HIV but are expensive
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Rubella: virus
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spread coughs & sneezes
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Rubella rash MMR vaccination
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If contracted during early pregnancy, rubella may cause, blindness, deafness, low birth weight and heart abnormalities
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SALMONELLA: bacterium
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salmonella lives in raw and undercooked meat, eggs, and the gut of chickens.
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If meat is not thawed or cooked fully, bacteria on the outside will be killed but not those on the inside. They will breed quickly producing a toxin.
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The toxin inflames the gut when eaten, causing fever, pain, vomiting, diarrhoea, dehydration and eventually death. It is a big problem for old and weak people.
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It can be prevented by the use of antibiotics cooking meat fully.
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GONORRHOEA: bacterium
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Play video link
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TUBERCULOSIS: bacterium
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The TB bacterium enters the lungs and reproduces forming swellings that burst and bleed. Sufferers cough up blood stained phlegm.
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TB pustules in cattle lungs
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Pustules appear as ‘shadows’ in a lung x-ray
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It is spread through untreated milk, flies and by inhalation. It can be treated with antibiotics.
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Prevention immunisation of cattle and humans, good hygiene and pasteurisation of milk.
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Immunisation: 1. Test if you are immune by injecting harmless antigens under the skin (Heaf test). If you carry antibodies a reaction occurs producing red swellings. 2. Vaccine (BCG) contains a weakened form of TB bacterium. Immunity lasts about 10 years.
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ATHLETES FOOT: fungus
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Spread: prevention: Dry between toes Don’t share towels
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Cure: anti-fungal cream & powders
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The First Line of Defence Mucous membranes – produce mucus which traps dirt & bacteria. Cilia sweep it to the back of the throat where it is swallowed Skin – acts as a barrier to prevent entry of microbes Clotting- seals skin & prevents entry of microbes
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Occurs when part of the skin is cut. It happens to form a barrier against microbes while new skin is being re-grown.
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When you become ill through a disease-causing organism you eventually recover as your body's defences defeat the invading pathogen.
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Antibodies fit over antigens antibodies microorganism lymphocyte antigen
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phagocyte nucleus bacterium 1. Strands of cytoplasm engulf bacterium 2. Enzymes digest the bacterium
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The reactions which take place the FIRST time an antigen enters the body is called the PRIMARY RESPONSE The reactions which take place the SECOND time an antigen enters the body is called the SECONDARY RESPONSE
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Number of antibodies 1st exposure to antigen 2nd exposure to antigen Time Pathogen has time to reproduce and cause symptoms while WBCs make correct antibody against antigen Memory cells recognise antigen and quickly make antibodies before pathogen can reproduce
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VACCINATION
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NATURAL IMMUNITY ARTIFICIAL IMMUNITY
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antibodies slowly produced Antibodies rapidly produced Small numbers of antibodies produced Large numbers of antibodies produced Antibody numbers fall quickly Antibody numbers remain high for longer NATURAL IMMUNITY ARTIFICIAL IMMUNITY
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Body makes antibodiesBody receives antibodies from somewhere else Memory lymphocyte cells made No memory lymphocyte cells made so disease can’t be fought at a later date Long lastingShort lasting AQUIRED & ACTIVE IMMUNITY INNATE & PASSIVE IMMUNITY
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Explain why Jenner waited a period of time between infecting James with cowpox and then small pox. Why do you think that most immunisation programmes are aimed at young children and not adults? Why is it important that the micro-organisms used in vaccination are dead or modified in some way? This gave the white blood cells time to identify cowpox antigens and produce antibodies, which would then be able to destroy the smallpox virus when it was injected. Most diseases are caught in childhood, so children can be protected before they come across the disease. The person can still produce antibodies against the antigens on the micro- organism, but it cannot reproduce and cause disease.
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