Transcript Micro Life Revision Powerpoint

11/04/2016
Micro Life
Plant cells vs. Animal cells
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Both types of cell have these:
1) Cytoplasm this is where the
reactions happen
2) Nucleus –
The “brain” of
the cell
3) Cell Membrane –
holds the cell
together
Only plant cells
have these:
4) Cell wall – provides
support
5) Chloroplasts –
contain chlorophyll
6) Large Vacuole
– contains sap
Microbes
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Microbes are micro organisms that are too small to be seen. A
pathogen is a microbe that can cause diseases if it enters the
body:
They can be
breathed in
through the
mouth or nose
…or other
natural
openings…
They can be
ingested (eaten)
through the mouth
They can enter
through cuts or
bites in the skin or
just by touching
something
Disease
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A disease is any condition where the body isn’t working as it should. This
could be caused by a malfunction in the body (as with diabetes), or it could
be caused by the two types of MICROBE:
Bacteria
Viruses
•1/1000th mm big
•1/1,000,000th mm big
•Living cells (some are harmless)
•Genetic info inside a protein coat
•Grow very quickly
•Not affected by antibiotics
•Affected by antibiotics
•Release poisons
•Examples: food poisoning,
tetanus, sore throats
•Examples: colds, flu, polio,
chicken pox
Fungi
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Fungi are another form of microbe. There are many
different varieties ranging from bread mould to mushrooms.
Fungi are useful because they are natural decomposers. They
also produce an important chemical called antibiotics which
destroy bacteria.
Microbes: our defence against them
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Our bodies have many defence mechanisms against invading
microbes:
The skin acts
as a barrier
Stomach produces
stomach acid
If our skin is cut
platelets seal the
wound by clotting
Tears contain an
enzyme that kills
bacteria
The breathing
organs produce
mucus to cover the
lining of these
organs and trap the
microbes
Fighting disease
If microbes do enter our body they need to
be neutralised or killed. This is done by
WHITE BLOOD CELLS:
White blood cells do 3 things:
1) They eat the microbe
2) They produce antibodies to
destroy the microbe
3) The produce antitoxins to
neutralise the poisons produced
by microbes
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Producing antibodies
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You’re going
down
Step 1: The white blood cell “sees”
the antigen (microbe)
Step 2: The cell produces
antibodies to “fit” the antigen
Step 3: The antibodies fit onto the
antigens and cause them to “clump”
Step 4: The antigens are “eaten”
by the white blood cells
Fighting disease
NATURAL IMMUNITY
This is when antibodies are produced
by a person when needed or they are
passed on by the mother during
pregnancy.
ARTIFICIAL IMMUNITY
A vaccine with dead microbes is injected
– the body is “tricked” into producing
antibodies ready for the real thing.
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Antibiotics
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• What are antibiotics?
• Why are human cells unharmed by
antibiotics?
An antibiotic is a poison that works to
destroy bacterial cells while leaving human
cells unharmed. Antibiotics destroy the cell
wall of bacteria. As viruses have no cell wall,
they have no effect on viruses.
Using Antibiotics
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Antibiotics can be used to kill bacteria. When taking an antibiotic,
you must complete the course. For example, the doctor might say
that it must be taken for a full 5 days. What do you think will
happen if you stopped taking the antibiotic after 2 days because you
are feeling better?
However, there are also problems with using antibiotics:
1) Overuse of antibiotics can lead to
bacteria becoming resistant
2) Antibiotics have no effect on a
virus, like the common cold. A virus
must be allowed to “run its course”.
Brainpop movies watched in class:
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Immune System
Vaccines
Avian Flu
Bacteria
Viruses
Teeth
Antibiotic resistance
Aids
Swine Flu