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· Bacteria cells have cell walls (keep their shape), a strand of DNA in
the cytoplasm (controls cell's activities) and a flagellum (for
· Come in 4 shapes: rods, curved rods, spheres and spirals.
· Bacteria consumes organic nutrients from surroundings for
energy but some produce their own nutrients.
· Different bacteria can survive in any habitat.
· They produce by asexual reproduction by binary fission. They
reproduce very quickly, even quicker when it's warm with a good
source of nutrients which is why you must store food correctly.
· You can grow bacteria on an agar plate but have to take certain
precautions to make sure that you don't get infected and the
sample does not get contaminated.
· Bacteria can be used to make yoghurt by heating, cooling then
heating and adding flavourings.…read more

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Microorganisms and Disease
· Viruses can only reproduce inside living cells so they
must infect another cell in order to multiply.
· Diseases can be transmitted in different ways: in food,
in water, by airborne droplets and through contact.
· Good sanitation and public health measures have led
to a low incidence of disease as they are better
educated and have better health services.
· Poor sanitation leads to a high incidence of disease.
Developing countries are likely to have a higher
incidence of disease as they are less likely to be able to
afford good sanitation and health measures.…read more

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Treating Infectious disease
· The microorganism enters the body, it then reproduces rapidly producing
more microorganisms, these then produce toxins which damage cells and
tissues. The toxins then cause the symptoms as can your immune system
response. The time between exposure and response is called the
incubation period.
· Antiseptics are used outside the body to prevent infections. Antibiotics are
used inside the body to treat those already infected, but these only work
on bacteria- viruses aren't affected.
· Mutations in DNA can lead to bacteria becoming immune to the antibiotic,
these will then survive and pas their genes onto their offspring which then
becomes more common in the population and overtime means that the
bacteria becomes immune to the antibiotics and become very hard to
treat (MRSA).
· The more often antibiotics are used, the bigger the problem of antibiotic-
resistance becomes. Doctors should only prescribe them when it's really
necessary and that people finish a whole course even if they start to feel
better as this increases the risk of antibiotic resistant bacteria emerging.…read more

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More on Infectious Diseases
· Diseases spread quickly after natural disasters; sewage
systems are damaged which leads to increase in
cholera, homes are destroyed so temp. camps can lead
to poor sanitation, health services are disrupted by
damaged transport links, electricity supplies are
damaged which means food goes off.
· Pasteur- came up with the germ theory (microbes in
air cause disease and decomposition).
· Lister- started using antiseptic, found that sepsis was a
type of decomposition so needed to kill the microbes
from the air getting into wounds.
· Fleming- discovered antibiotic penicillin.…read more

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· When yeast respires anaerobically it produces ethanol, carbon
dioxide and energy. This is called fermentation. It is used to make
beer and wine.
· It can also respire aerobically which produces more energy. It is
the same for yeast as it is for animals and plants.
· Yeast reproduces faster when its warmer but not too hot, there is
more food, there isn't a build up of toxic waste products, the pH is
just right (not too high or low) and there is a lot of oxygen
· A way to measure how fast yeast is reproducing is to measure
how much glucose it breaks down (the faster it's reproducing, the
more glucose will be broken down).
· Yeast is used to treat sugary water used in food-processing plants
as it uses up all the sugar in respiration meaning that the water
doesn't cause pollution and bacteria in the water can't feed on
the sugar, use up all the oxygen and kill other organisms.…read more

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