Transcript micro-organisms & disease

•Only visible under the microscope
•Include bacteria, fungi & viruses
1. Nutrient broth
poured into flask
2. Neck of flask heated
and pulled into an S
shape
4. Broth allowed to cool. It
stayed clear and fresh for
months.
3. Broth boiled for a few
minutes to kill any microbes
present and drive out air
5. Neck of flask broken off
without touching it with hands.
Broth went bad within a few days.
It became cloudy and was soon
teeming with microbes.
Microbe
VIRUS
Disease
HIV leading to AIDS
Measles
Rubella
Mumps
Colds & Flu
Polio
BACTERIUM Salmonella food poisoning
Gonorrhoea
Tuberculosis
Chlamydia
FUNGUS
Athletes Foot
AIDS: HIV virus
Protein
coat
Genetic
material
Stops immune system working.
pneumonia
cancers
Spread & prevention
Anti-viral drugs help to control HIV
but are expensive
Rubella:
virus
spread
coughs & sneezes
Rubella rash
MMR vaccination
If contracted during early
pregnancy, rubella may cause,
blindness, deafness,
low birth weight and
heart abnormalities
SALMONELLA: bacterium
salmonella
lives in raw
and
undercooked
meat, eggs,
and the gut of
chickens.
If meat is not thawed or cooked fully,
bacteria on the outside will be killed but
not those on the inside. They will breed
quickly producing a toxin.
• The toxin inflames
the gut when eaten,
causing fever, pain,
vomiting,
diarrhoea,
dehydration and
eventually death.
• It is a big problem
for old and weak
people.
It can be prevented by
the use of antibiotics
cooking meat fully.
GONORRHOEA: bacterium
Play video link
TUBERCULOSIS: bacterium
The TB bacterium enters the lungs
and reproduces forming swellings
that burst and bleed. Sufferers
cough up blood stained phlegm.
TB pustules in cattle lungs
Pustules appear as ‘shadows’ in a lung x-ray
It is spread
through
untreated milk,
flies and by
inhalation.
It can be
treated with
antibiotics.
Prevention
•
immunisation of cattle and humans,
• good hygiene and
• pasteurisation of milk.
Immunisation:
1. Test if you are immune by injecting harmless
antigens under the skin (Heaf test). If you carry
antibodies a reaction occurs producing red
swellings.
2. Vaccine (BCG) contains a weakened form of
TB bacterium. Immunity lasts about 10 years.
ATHLETES FOOT: fungus
Spread:
prevention:
Dry between toes
Don’t share towels
Cure: anti-fungal cream & powders
The First Line of Defence
Mucous membranes –
produce mucus which traps
dirt & bacteria. Cilia sweep
it to the back of the throat
where it is swallowed
Skin – acts as
a barrier to
prevent entry
of microbes
Clotting- seals
skin &
prevents entry
of microbes
Occurs when
part of the skin
is cut. It
happens to form
a barrier
against
microbes while
new skin is being
re-grown.
When you become ill
through a disease-causing
organism you eventually
recover as your body's
defences defeat
the invading
pathogen.
Antibodies
fit over
antigens
antibodies
antigen
microorganism
lymphocyte
phagocyte
bacterium
nucleus
1. Strands of cytoplasm engulf bacterium
2. Enzymes digest the bacterium
• The reactions which take place
the FIRST time an antigen enters
the body is called the PRIMARY
RESPONSE
• The reactions which take place
the SECOND time an antigen
enters the body is called the
SECONDARY RESPONSE
Number of antibodies
Pathogen has
time to reproduce
and cause symptoms
while WBCs make
correct antibody
against antigen
Memory cells
recognise antigen
and quickly make
antibodies before
pathogen can reproduce
Time
1st exposure
to antigen
2nd exposure
to antigen
VACCINATION
NATURAL
IMMUNITY
ARTIFICIAL
IMMUNITY
NATURAL
IMMUNITY
ARTIFICIAL
IMMUNITY
antibodies slowly
produced
Antibodies rapidly
produced
Small numbers of
antibodies produced
Large numbers of
antibodies produced
Antibody numbers fall
quickly
Antibody numbers remain
high for longer
AQUIRED &
ACTIVE
IMMUNITY
INNATE &
PASSIVE
IMMUNITY
Body makes antibodies
Body receives antibodies
from somewhere else
Memory lymphocyte
cells made
No memory lymphocyte
cells made so disease can’t
be fought at a later date
Long lasting
Short lasting
Explain why Jenner waited a period of time between infecting James with cowpox
and then small pox.
This gave the white blood cells time to identify cowpox antigens and produce
antibodies, which would then be able to destroy the smallpox virus when it was
injected.
Why do you think that most immunisation programmes are aimed at young
children and not adults?
Most diseases are caught in childhood, so children can be protected before they
come across the disease.
Why is it important that the micro-organisms used in vaccination are dead or
modified in some way?
The person can still produce antibodies against the antigens on the microorganism, but it cannot reproduce and cause disease.