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INFECTIOUS DISEASES (Pathogens (Microorganisms that cause infectious…
INFECTIOUS DISEASES
Pathogens
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Viruses cannot reproduce rapidly in the body, only inside a host cell. It invades the host cell and reproduces. The cell bursts open and dies.
Spreading can be reduced by washing hands, clean surfaces, vaccinations, etc.
Malaria
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Infected person is bitten by a mosquito, malaria pathogen passes into mosquito, mosquito bites another person, pathogen passes into that person
To stop spreading, we can drain areas of still water as mosquitos breed here, spray these areas with insecticides or sleep under mosquito nets.
Immune system
When the skin is damaged, pathogen can get in the body and into the bloodstream. The pathogens can multiply and release toxins which make us unwell.
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Phagocytosis: white blood cell detects the chemical released from the pathogen and moves towards it. It then ingests the pathogen and uses enzymes to destroy it.
Antibodies: The white blood cell releases antibodies that stick to the pathogen and trigger the pathogen to be destroyed. The antibodies will become specific to this pathogen. Antibodies stay in the blood for a long time and can protect us if the same pathogen enters our body.
Plant defence responses
Physical response: cellulose cell wall, waxy cuticle, bark, sharp thorns, hairs
Chemical response: antibacterial chemicals produced, can release poisons,
Mechanical responses: leaves droop or curl, mimicking other plants e.g. poisonous plants
Measles and HIV
Measles: red skin rash, spread by host sneezing or coughing, can cause breathing problems and brain damage, most are vaccinated against it.
HIV: flu-like illness, attacks persons immune system and severely damages it and it cannot fight infections any longer, spreads in exchange of fluids between human so it can be prevented by using contraception, treated with antiretroviral drugs
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In plants
Tobacco mosaic virus: causes discolouration in a mosaic on leaves, rate of photosynthesis is reduced so growth of plant is reduced.
Rose black spot: caused by a fungus, leaves produce purple or black spots and can fall off, rate of photosynthesis falls so growth of plant reduces, spread by water or wind, can be sprayed with fungicides or can be removed
Antibiotics
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Doctors use specific antibiotics to treat specific bacteria. But, antibiotics cannot kill viruses.
Testing medicine
Preclinical testing is on cells, tissues or live animals (ethics)
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Monoclonal antibodies
We inject a mouse with the antigen we want to make antibodies against. We extract the lymphocytes from the mouse. We select the lymphocyte that is producing the antibodies we need. We fuse this with a tumour cell as tumour cells can undergo mitosis.
A cell called a hybridoma cell is produced from fusing the lymphocyte with a tumour cell and this only produces the antibody that we need. We let this go through mitosis and multiply, and these can be collected and purified.
In plants (2)
Plants can be attacked by insects such as aphids. These extracts nutrients rom plants and cause stunted growth.
We can identify diseases by looking in manuals, taking it to a lab or using testing kits.
Vaccinations
A dead or inactive pathogen is injected into the body. The white blood cell produces antibodies to this pathogen and multiplies by mitosis. These copies stay in the blood and can help to destroy the same pathogen if it enters the body again.
Communicable: spread from person to person, spread by pathogens
Non-communicable: cannot spread from person to person
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Can be used inn pregnancy tests, in lab testing, in treating diseases