Download Microbes and Disease

Microbes and disease
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What are microbes?
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What are microbes?
Microbes are very small living things and
are sometimes called micro-organisms.
Microbes are so tiny that they cannot
be seen with the naked eye.
They can only be seen using a
microscope.
How many different microbes
can you name?
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Different types of microbes
There are three types of microbes:
bacteria
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viruses
fungi
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Bacteria fact file
Microbe: Bacteria (e.g. salmonella and streptococcus)
Size: 1/1000 mm
Shape: Bacteria can be spherical,
rod-shaped or comma-shaped.
Structure: Bacteria are singlecelled organisms. Their genetic
material is not contained within
a nucleus. Some cause disease,
but many are useful.
Reproduction: Bacteria reproduce very quickly. Two can
very quickly become four, then eight and so on.
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Structure of a bacterium
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How do bacteria divide?
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Virus fact file
Microbe: Virus (e.g. flu virus and HIV)
Size: 1/1,000,000 mm
Shape: Viruses have regular
and geometric shapes.
Structure: A virus is a simple
organism that does not display all
the characteristics of a living thing.
It is made up of a protein coating
and some genetic material.
Reproduction: Viruses can only grow and reproduce
within other living things. Viruses change and adapt to
their environment very quickly.
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Structure of a virus
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Fungi fact file
Microbe: Fungi (e.g. penicillium and yeast)
Size: Some fungi can
actually be seen with the
naked eye, others are slightly
bigger than bacterial cells.
Shape: Fungi come in
many different shapes.
Structure: Fungi have the most complex structures of all
the microbes. They feed off other living things.
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Structure of a fungus
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Looking at microbes
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Uses of microbes
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Using bacteria and fungi
Microbes have many uses that are based on the fact that
they can be grown.
Bacteria grow in milk to make
it ‘go off’.
This type of bacterial growth is
used to make milk into yoghurt.
Cheese is also produced using
certain strains of bacteria.
Fungi can also be used to make food. The meat
substitute Quorn™ is a protein produced using fungi.
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Using yeast
Yeast is a type of fungus and carries out respiration.
The respiration of this microbe can be used in different
ways in baking bread and in brewing.
The aerobic respiration of yeast
is used to make bread rise.
Yeast uses the sugar in bread dough
to carry out aerobic respiration:
glucose
+
oxygen 
carbon
dioxide
+
water ( + energy)
What gas produced by the aerobic respiration of yeast
causes bread to rise?
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Using yeast
The anaerobic respiration of yeast
is used to make beer and wine.
In this case, the yeast respires
without oxygen and produces
alcohol (ethanol). This process
is known as fermentation.
Yeast converts the sugar into
alcohol by anaerobic respiration:
carbon
glucose 
dioxide
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+
ethanol ( + energy)
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How microbes cause disease
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Microbes can cause disease
The diseases caused by microbes, and their severity,
depend on the type of microbe:
bacteria
virus
fungi
food poisoning
influenza (flu)
fungal sinusitis
sore throats
mumps
athlete’s foot
tuberculosis (TB)
chickenpox
tetanus
smallpox
onychomycosis
(causes discoloured
toe nails)
cholera
polio
typhoid
HIV / AIDS
bacterial meningitis
viral meningitis
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How do microbes enter the body?
Microbes can enter the body in many different places:
eyes
ears
nose
mouth
genitals
cuts
skin
How do the diseases caused by microbes spread?
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How does disease spread?
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Fighting disease
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Defences against disease
Harmful microbes can
cause disease by
damaging body cells.
Once microbes have
entered the body, it’s
important that they are
removed as quickly as
possible to reduce
damage.
The body’s immune system uses specialized cells called
white blood cells to identify and destroy the microbes.
How does the body try to stop harmful microbes from entering?
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The body’s defences
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What do white blood cells do?
If harmful microbes enter
the body the immune
system produces white
blood cells to help
defend it from microbes.
bacteria
antigen
Some white blood cells
can destroy microbes
by engulfing them.
white blood
cell
Some white blood cells are able to produce chemicals
called antibodies. These pair with matching antigens on
the surfaces of microbes and so help the white blood cells
to engulf microbes.
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Destroying microbes
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Producing antibodies
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Preventing the spread of disease
There are several methods that can help reduce the
spread of disease:

disinfecting surfaces

disinfecting skin using antiseptics

sterilizing equipment

using food preservatives in food

personal hygiene.
The spread of disease can also be reduced by vaccinating
the population and using antibiotics.
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What are antibiotics?
Antibiotics are chemicals used to treat bacterial infections.
These chemicals kill or stop the growth of bacteria.
However, some types of
bacteria are no longer affected
by certain antibiotics – this is
called antibiotic resistance.
This can be a problem as
without effective antibiotics
some people might not be
able to fight the infection
themselves.
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What are vaccines?
Vaccines can protect people from diseases, such as measles.
Vaccines contain dead or
weakened strains of the harmful
microbe that causes the disease.
This stimulates the immune system.
If the person comes into contact
with the microbe again the immune
system can destroy it quickly and
effectively.
Why is it important that everyone
is vaccinated?
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Why do we need to have vaccinations?
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Who invented vaccines?
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Summary activities
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Glossary
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Anagrams
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Multiple-choice quiz
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