22/03/2016
How do we prevent bacteria
spreading ? 22/03/2016
Answer Q 1-4 in full sentences
(Q 2 may be done by completing
the table.
22/03/2016
Agar jelly
22/03/2016
Is used to grow microbial
populations in. It contains all
of the necessary nutrients for
a microorganism to grow on.
Aim To investigate the
effectiveness of different
had washing methods for
removing bacteria.
Independent variable
Dependent variable
Control variable
Prediction
Agar jelly
Control no
washing
Agar jelly
22/03/2016
Method
1. Set up apparatus as
shown.
Treatment 1
2. Label lid with treatments
and your name.
Treatment 2
3. Seal lid
4. Leave for 1 week (take a
picture)
Defense against disease
22/03/2016
1. Describe how the body
protects its self from disease
2. Know how a vaccine works
3. Be able to use correct
scientific terminology when
describing vaccinations and the
immune system.
Microbes: our defence against them
22/03/2016
Our bodies have many defence mechanisms against invading
microbes:
The skin acts
as a barrier
Stomach produces
stomach acid to
kill bacteria
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. Ciliated
cells sweep the
mucus out.
Fighting disease
22/03/2016
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-engulf the microbes
https://www.youtube.com/wat
ch?v=Z_mXDvZQ6dU
Fighting disease
22/03/2016
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:
2) They produce antibodies to neutralise the microbe
You’re going
down
Step 1: The white blood cell
detects the antigen (microbe)
Step 2: The cell produces
antibodies to “fit” the antigen
Producing antibodies
22/03/2016
You’re going
down
Step 1: The white blood cell
detects 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” and
make them easier to be engulfed
Step 4: The antigens are “eaten”
by different white blood cells
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:
3) They produce antitoxins to neutralise the poisons
produced by microbes
https://www.youtube.com/watch?v=Bf2t8n1ib
wQ
22/03/2016
Key points
22/03/2016
• the pathogens are not the disease they cause the disease
• white blood cells do not eat the
pathogens - they ingest them
• antibodies and antitoxins are not living
things - they are specialised protein
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. (breast milk)
ARTIFICIAL IMMUNITY
A vaccine with dead microbes is injected
– the body is “tricked” into producing
antibodies ready for the real thing. This
is called PASSIVE IMMUNISATION
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Vaccinations
AIM: Explain how vaccinations work .
A vaccine is an injection of a dead; weak
or a part of a micro organism that
stimulates the white blood cells to
produce antibodies.
How do vaccinations work ?
Vaccinations kick-start your
white blood cells into making
antibodies so you become
immune to a disease without
catching it.
Immune- not effected
by/protected from.
Small amounts of
dead or weakened
forms of MO’s
injected.
White
blood cells
recognise
MO’s
White blood cells
makes antibodies,
which attach to
antigens and
clump the MO’s
together.
White blood
cells makes
another
white blood
cell and a
memory cell
Different type of
white blood cell
digests the clump of
MO’s
Phatgocytosis.
If the real MO invades
the memory cell
remembers and makes
more white blood cells
with the right type of
antibody.
Using Antibiotics
22/03/2016
Antibiotics can be used to kill bacteria. However, there are
two problems:
1) Overuse of antibiotics can lead to
bacteria becoming resistant to that
antibiotiv
2) Antibiotics have no effect on a
virus, like the common cold. A virus
must be allowed to “run its course”.
22/03/2016
Read page 48 and answer
questions
How do we prevent microbes
destroying our food?
22/03/2016
Quick quiz
22/03/2016
1. Which is the smallest type of microbe
and give an example of a disease it can
cause.
2. How fast can bacteria reproduce?
3. Give 3 uses for microbes
4. Give the 2 equations for anaerobic
respiration
5. Give 4 ways to protect food from
microbes.
6. What 7 processes does MRS GREN
represent?
Anti bacterials
22/03/2016
Microbes grow everywhere which can cause
problems. They can cause food to spoil and ___,
they can ______ cuts and scrapes, they get into
open wounds and cause infections and _______.
In order to remove ________, anti bacterials
are often used. For example, ______, Savlon,
TCP and tea tree oil are all anti bacterial agents.
Alternative methods are to heat up an item to a
____ temperature for long enough to ____ the
microbes.
Bleach, rot, kill, high, microbes, infect, disease.
Microbes
22/03/2016
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
Microbes: our defence against them
22/03/2016
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