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Bacterial Structure
Bacteria are a type of cell but they have a very unique structure and are
not very similar to other cells such as animal cells or plant cells. Though
they do have some of the properties of both.
Below is a diagram of an average bacterial cell.
Bacterial DNA can be found in two forms, firstly Chromosomal and
which can be found free floating in the cytoplasm of the cell.…read more

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An example for this is a gene for Antibiotic
resistance. This is found within Plasmid DNA. Plasmids can be
transferred from one bacterial cell to another, if the plasmid transferred
hold a gene to cause resistance to an antibiotic then the cell it is
transferred to will become antibiotic resistant. This is believe to be the
cause of the MRSA (superbug). Plasmids can replicate on their own
and due to this are able to exist in bacterial cells even once replication
takes place.…read more

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Polar or nonpolar region of the membrane.
The plasma membrane also has proteins embedded with it, such as
Proton Motive Force
The plasma membrane is also the site of Energy conservation by the
Protomotive force. During respiration H+ ions are produced and some
of them are transported out of the cell. This causes the outside of the
cell to have a higher concentration of H+ ions then the inside of the cell,
this is called a gradient.…read more

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When classifying between Gram Negative and Gram Positive we
describe the bacteria as being either gram Negative or Positive rather
than saying the Membrane is Gram positive or negative.
Gram negative bacteria have a plasma membrane and an outer
membrane. this is a key way to identify if you have a gram negative
bacterium as they will have an inner and outer membrane.
They also contain a thin layer of Peptidoglycan and between the
Peptidoglycan and the inner membrane is the periplasmic space.…read more

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The Gram Positive wall can be identified easily as it only has one
membrane, (the plasma membrane). It also has peptidoglycan but this
is far thicker in a Gram positive cell wall. There is also no periplasmic
space as the peptidoglycan is pressed against the plasma membrane.
This Peptidoglycan how ever, has Teichoic acid embedded into it and
as a result this gives the wall strength. There is also some protein
embedded into the Peptidoglycan.
Peptidoglycan is made of the substance Murein.…read more

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NAM). The Sugar back bone is linked by tetrapeptised. This is shown
BetaLactam Antibiotics
Half of the antibiotic's we used today are Beta Lactams. This type of
antibiotics acts on the cell wall of bacteria. An example of this is the
famous Penicillin. Penicillin works by inhibiting reactions which form the
cross linking in peptidoglycan. As a result of this the chains cannot form
cross links and end up being weak which can cause the cell to burst.…read more

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They then need to be exposed to Grams Iodine for 1 minuet and then
rinsed with water, they should both still be purple.
At this point either 95% ethanol or Acetone is washed over the cells.
The gram negative bacteria at this point will lose their colour whereas
the gram positive will remain purple. They then need to be rinsed in
water for between 1030 seconds
Finally Safarinin is added for about 3060 seconds, the cells need to be
rinsed and then blotted.…read more

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Not all bacteria, but some bacteria form spores, and some bacteria only
form spores at certain times. Spores are very tolerant of extreme
conditions, such as high heat, radiation and chemicals. The Spores only
germinate when in conditions that are favourable for the bacterial cell to
begin growth.
Bacteria divide as all cells do, though they do not divide in the same
way, or using the same mechanism as mitosis. Bacteria go through the
process of binary fission.…read more

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The sample is then incubated and allowed to grow, the colonies are
then counted.
Dry Cell Weight
Sample is taken
The sample is then desiccated (meaning dried out)
The sample is then weighed
Turbidity is the measurement of how clouds a liquid is when bacteria are
in it. When light is passed through the liquid some of the bacteria is
absorbed by the bacteria and the loss of light is detected and can be
measured.…read more


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