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B1 L1
Learning Objective
To be able to describe how we treat and prevent disease
Key words: Medicine, Penicillin, antibiotics, immunisation, vaccine
Starter activity: How do we treat disease, what would you use to treat salmonella
(bacterial infection)? What would you use to treat the common cold (virus)?
For bacterial Infections - Use
Antibiotics
For viruses – Don’t use
Antibiotics because they do
not work against them so it is
left alone for the body to deal
with.
Success Criteria
At the end of this lesson it will be:
Best
Better
Good
Able to explain how vaccination
makes human beings immune to a
specific pathogen.
Able to explain how we develop antibiotics.
Able to state why antibiotics cannot treat viruses
Last lesson link
Immunity
• Once your white blood cells destroy a type of
pathogen, you are unlikely to develop the same
disease again.
• This is because the white blood cells recognise
the pathogen the next time it invades the body
and the correct antibodies will kill it very quickly
before it can affect you.
• This makes you Immune to the disease and is
known as Immunity.
How we get rid of Side effects
(Painkillers)
• If you have a sore throat you
take a lozenge (medicine) to
reduce pain (painkiller).
• However the sore throat is
only a side effect of the
pathogen and it will not kill the
pathogen just take the pain
away.
How do we kill Bacteria?
• Antibiotics – These medicines kill bacteria, there are
many types used to treat people.
– Penicillin was the first antibiotic discovered and works by
breaking down the cell wall of the bacteria causing them to
burst.
Discovery of Penicillin
1. How was penicillin discovered?
2. Why did he know that penicillin killed bacteria?
THEY CANNOT KILL VIRUSES HOWEVER!!
Why can’t antibiotics kill viruses??
• Antibiotics can’t kill viruses because viruses
live and reproduce inside body cells.
• It is very difficult to develop medicine which
kills the virus without also destroying the cell
Learning objective check
Good
Able to state why antibiotics cannot treat viruses
How are they developed?
• Most antibiotics are developed
and tested in sterile petri dishes
(contains no other bacteria)
1. Bacteria are placed on small discs of
paper containing antibiotics.
2. The discs are placed in a dish
containing bacteria growing on a gel.
• The clear zone is where the
bacteria have been killed.
• The clear zone is where the bacteria have been
killed. Which antibiotic is most effective? Why?
Learning objective check
Better
Able to explain how we develop antibiotics.
How can we combat viruses then?
By Immunisation.
We can understand immunisation by learning
about small pox and how it was combatted by a
man called Edward Jenner.
What is small pox?
• A viral disease similar to chicken pox.
• It killed one in three of those who caught it
and badly disfigured those who were lucky
enough to survive catching it.
Before Jenner, children were infected with smallpox
when they were young in order to give them immunity
from it, however many children died as a result.
Edward Jenner
Lock and Key
THE COW POX WAS A VERY SIMILAR KEY TO THE SMALL POX
AND THEREFORE THE ANTIBODIES MADE BY THE BODY TO KILL
THE COWPOX COULD ALSO KILL THE SMALLPOX VIRUS
What did Jenner do?
• In 1796 he injected a small boy with cowpox.
• He used the pus form a blister on a cow!
• A few weeks later, he injected him with
smallpox.
• The boy survived.
Is it morally right what Jenner did?
Another vaccination method
• Another method of vaccination is to give the
person a weakened form of the virus.
• This is exactly what Louis
Pasteur did with rabies virus
Lock and Key
Same lock and key just that key is weakened
and so does no harm
How do we gain immunity without
contracting the disease?
• By Immunisation.
• A new-born baby receives antibodies from its
mother in the first few days of feeding.
• When you’re a young child you are immunised
to protect you from very harmful diseases,
such as polio, measles, mumps and rubella.
The process of vaccination
• Immunisation (vaccination) involves:
1. Injecting or swallowing a vaccine containing small amount
of dead or weak form of the pathogen.
2. As pathogen is weak, no illness but white blood cells still
respond and produce antibodies to destroy the pathogen.
This makes you immune to future infection by that
pathogen
Why would you now be immune to
that pathogen?
• Your white blood cells will recognise if the
pathogen gets into your body and will respond
quickly by producing antibodies.
• The pathogen does not get a chance to
reproduce enough to make you ill. (i.e. cannot
produce enough toxins to make you feel ill)
Learning objective check
Best
Able to explain how vaccination make
us immune to a specific pathogen.
Exam question
(5)
How can the following drugs be
used to treat disease?
Painkillers
Antibiotics
How do animals gain immunity from
bacteria and viruses without
contracting them?
Why can’t antibiotics be used to kill viruses?
Explain how vaccination works:
How are antibiotics developed and tested? And how can
you tell which is most effective?
What is a sterile culture in petri dish
.
Give 2 reasons it is important to keep
cultures sterile. .
What 3 diseases does MMR vaccine protect from?