http://www.sherwood.k12.or.us/?q=node/522
Taken from: Porter, S. (2003). Microbes and disease.
http://mrsimonporter.wikispaces.com/Year+8+Science
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As the name suggests, MICROBES are
microscopic organisms.
They can only
be seen using a
microscope.
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Microbe uses
Microbe can be put into a number of categories. The four
types which you need to know about are listed below:
BACTERIA
VIRUS
FUNGI
PROTOZOA
A living organism must be able to
demonstrate that it can perform ALL the 7
life processes.
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition
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Microbe pictures
Microbes multiply very
rapidly. Two can, very
quickly, become four then
eight and so on.
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Microbe uses
Microbes have many uses. This is mainly because we
can ‘grow’ microbes if we wish to.
Microbes (in this case bacteria)
will grow in milk to make it ‘go
off’. This is used in the yoghurt
making process. Cheese is also
another product made due to the
use of microbes in industry.
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Microbe uses
Yeast is a microbe which RESPIRES to give off carbon
dioxide. This is used in baking bread and in winemaking.
We can use the AEROBIC respiration of yeast to
make bread rise.
Yeast uses the sugar in bread dough to respire.
The reaction is:
Glucose + oxygen
carbon + water + energy
dioxide
The carbon dioxide given off causes the bread to rise.
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Microbe uses
We can use the ANAEROBIC respiration of yeast to make
beer and wine. This means that the yeast respires
WITHOUT oxygen. This process produces alcohol
(ethanol) and is known as FERMENTATION.
Yeast converts the sugar into alcohol:
Glucose
carbon + ethanol + energy
dioxide
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Virus
A virus is a simple organism which does not completely
display ALL the characteristics of living things. It consists of
a protein coating and a strand of genes.
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Bacteria
A bacteria is a single celled organism which does not
completely have a nucleus. Their genes are found in the
chromosomes.
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Fungus
Yeast is a fungus and as can be seen below, it has a more
complex structure than the other two types of microbes.
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Microbes can cause disease
The diseases and their severity caused by microbes depend
on the type of microbe. Some of these are listed below.
VIRUSES
BACTERIA
FUNGI
Influenza (flu)
Food poisoning
fungal sinusitis
Mumps
Sore throats
Athletes foot
Chickenpox
Tuberculosis (TB)
Smallpox
Tetanus
Onychomycosis
Causes discoloured
toe nails
Polio
Cholera
Rabies
Typhoid
German measles
Whooping cough
Viral
meningitis
Bacterial
meningitis
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How do microbes enter the body
Eyes
Ears
Mouth
Nose
Skin
Cuts
Genitals
A number of these places where microbes can
enter the body are defended.
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How do microbes spread?
The spreading of microbes and disease is known as
Transmission.
• Transmission by air
A cough or a sneeze can release millions
of microbes into the air which could then
infect somebody else.
• Transmission in water
Dirty water can transmit many
diseases, for example, cholera which
can be transmitted by drinking the
water.
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• Transmission by animals
An animal, e.g. a mosquito
(which spreads the
MALARIA PARASITE) can
carry the microbe from one
place to another.
• Transmission by contact
Many microbes can be exchanged from one
person to another by direct or indirect contact:
• Direct contact by hand.
• Indirect contact by walking on a wet floor
already contaminated by someone else who
has Athlete’s foot.
• Sexual contact.
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• Transmission by contact
There are other forms of indirect contact, the
transmission of microbes from mother to unborn child.
Transmission through the Placenta
If the mother develops the HIV/aids infection, it
can be passed on to the unborn child through the
placenta.
Transmission via Breastfeeding
A child can also pick up microbes from the
mother, via the milk, if the child is being
breastfed.
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How do we stop microbes spreading disease
We can prevent the spread of disease by making sure that
good hygiene is used in key places such as bathrooms and
kitchens.
Chemicals called antibiotics can be
used to treat bacterial infections.
People can be immunised against
some diseases by the injection of a
vaccine.
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Fighting disease
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Fighting disease
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For Thursday 26th January
1. HOMEWORK: On your notebook.
- Summary about the types of transmission.
- From tha table on page 11, select 5 diseases caused by
virus and 5 caused by bacteria and find the scientific name
of the microbes that cause them.
- Afterwards, select one disease and explain the way it is
transmitted and its treatment.
2. We will start a lab practice: Diversity of
microorganisms in our environment. You need to bring:
- Lab coat (no body can enter with out one)
- In groups of 3, select 4 different places around the school
to compare the diversity of microbes between them.
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