How bacteria can affect the lives of humans and other organisms (A2 Unit 5 25 Mark Essay)

This is an essay that I wrote for a past paper.  My teacher marked it at 22/25 and suggested that to improve, I should have talked more about the nitrogen and nutrient cycles and how bacteria are actively involved in them. 

I got really into this essay, and am a very fast writer! :)

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  • Created on: 08-04-14 16:33
Preview of How bacteria can affect the lives of humans and other organisms (A2 Unit 5 25 Mark Essay)

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Tom Barnes
How bacteria can affect the lives of humans and other organisms.
Bacteria are small, prokaryotic organisms. This means that they do not have a distinct nucleus.
Instead their DNA takes the form of a plasmid, which is a cyclical ring of DNA.
Bacteria have a lot of positive effects on our lives and the lives of other organisms; however
experiences of illness, spoiled food and articles in the media mean that we probably associate them
more with their negative effects on life.
Bacteria can damage our health in several ways:
Bacteria release toxins that can damage body tissues and cells,
They can release toxins that can inhibit the action of vital enzymes in life processes
The sheer numbers of them can cause damage and impaired function of organs/tissues in the
An example of a bacterial action of destruction is that of the cholera bacterium. The full name of this
bacterium (including the genus) is Vibrio Cholerae. This bacterium has a flagellum which is a
tentacle-like projection of membrane from one part of the cell. The bacterium enters the body
through consumption of water (and less commonly food) contaminated with the faecal matter of
others who are suffering from cholera. The majority of the bacteria are destroyed by the acidic
conditions in the stomach, however any that make it through the stomach into the small intestine can
go on to cause severe damage. In the small intestine, the bacteria use their flagellum to propel
themselves in a corkscrew like motion into the epithelium of the small intestine. Here they begin to
secrete a toxin into the lumen of the intestine. This toxin has an interesting effect on the conditions in
the lumen as it lowers the water potential in the lumen (makes it more negative). To counteract this
action, the surrounding cells of the intestine secrete water via osmosis into the lumen to try and form
equilibrium in the two water potentials (inside and outside the surrounding cells). Here, the water
mixes with the faeces in the intestine to form diarrhoea. This process repeats constantly as the
bacteria multiply and soon the patient suffers from significant dehydration. Without treatment, the
patient is very likely to die from dehydration and shrinking of the brain which can cause irreversible
Other diseases such as bacterial meningitis are caused by Neisseria meningitis which can cause
infections of the lining of the brain, leading to brain and nerve damage, and possible septicaemia
(infection of the blood). Another collection of diseases are the MRSA group of diseases which mean
that all milk sold in shops in the UK and other countries in the world has to be pasteurised before
consumption to remove these potentially dangerous pathogens. This can affect the welfare of the
cattle used for milk production as it means that cow's milk usually has to be collected in sterile
equipment, and some people think that this is uncomfortable for the animals and shouldn't be
encouraged, however removing these precautions could potentially lead to an increase in MRSA
linked conditions in humans.
Following on from the point of animal welfare, the outbreak of diseases such as Transmissible
spongiform encephalopathy related diseases are improving the quality of meat inspection in terms
of human health, and the quality of living conditions for animals reared for livestock purposes.

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Tom Barnes
On the other hand, the disease Mycobacterium Tuberculosis Bovis is a disease that is more
commonly known as Bovine TB. This disease is believed to be spread amongst cattle by carrier
badgers that live nearby. The TB in the cattle could pose as serious health risks to humans, as
vaccinations are no longer mandatory, and the courses of antibiotics required to treat the disease
are very strong and take a long time to work.…read more

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Tom Barnes
Nitrogen fixing bacteria fix nitrogen into compounds that we can use, and rather interestingly have a
symbiotic relationship with plants such as those in the legumes family. They are allowed to live in
nodes in their roots, which provide the bacteria with a place to live and reproduce, and the plant
which nitrogen compounds which benefits the growth and reproduction of the plant. Furthermore,
bacteria are essential for the decomposition of organic material which allows for nutrients to be
recycled around ecosystems.…read more


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