Download The importance of penicillin

Year 8, unit 3
Cells
Name: .......................................................................... Class: .......................... Date: ......................
Lesson 4:Scientific discoveries
Worksheet:
The importance of penicillin
Part A
Read the information provided and answer the questions
We take our healthy lives for granted today, but before penicillin a simple scratch
from a rose thorn could have been enough to kill you. Bacteria could get into the
open sore and multiply. The infection would spread throughout your body, destroying
the cells and could eventually kill you.
Alexander Fleming had been studying bacteria for some time; how they grow larger
and divide in two. A single bacterium can become two in as little as twenty minutes.
Then two becomes four and four becomes eight.
1. If it takes 20 minutes for one bacterial cell to divide into two, how many bacteria
will be present in 2 hours?
It was a bad cold that helped Alexander Fleming discover there was a way to stop
bacteria growing. One day he was plating bacteria onto nutrient agar plates when a
drop fell from his runny nose, onto the plate. No bacteria grew where the drop fell.
Alexander knew there must be something in his nose mucus that killed the bacteria.
He called it lysozyme.
He then went looking for more ways to prevent bacterial growth. His next most
important discovery was again by accident. In 1928 he was eating sandwiches for
lunch one day while he prepared some new nutrient agar plates. He usually
disinfected these plates before using them, however this particular day he was in a
hurry to go away for a holiday so he left them on the bench. When he came back a
few days later, he noticed that they were covered in bacteria. As he sorted through
them, he saw a few crumbs from his sandwich sitting on one of the plates. Mould had
grown on the bread, and left a ring around it where the bacteria could not grow.
2. Why should you never eat in a laboratory?
Alexander Fleming tried to purify the ‘penicillin’ but was unable to grow it in large
enough quantities to be used. Twelve years later, World War II had started and many
people were dying from infected wounds. It was Australian Howard Florey and
German refugee Ernst Chain who developed a way to grow and purify large amounts
of the drug. Mass production was started immediately and as a result many people
survived the final battles of the war. Fleming, Flory and Chain were awarded the
1945 Nobel Prize in Physiology and Medicine for their discoveries.
© 2013 Education Services Australia Ltd, except where indicated otherwise. You may copy,
distribute and adapt this material free of charge for non-commercial educational purposes,
provided you retain all copyright notices and acknowledgements.
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Year 8, unit 3
Cells
Name: .......................................................................... Class: .......................... Date: ......................
Part B
Bacterial cells are different to plant and animal cells. They do not have a nucleus or
other membrane-bound organelles. Instead they have their genetic material (DNA)
and ribosomes moving freely in the cytoplasm.
A bacterial cell
DNA
Cell membrane
Ribosomes
Flagella
Cell wall
1. What role do ribosomes play in a cell?
2. What is the function of the cell wall in a cell?
All bacteria have cell walls similar to plants. Penicillin prevents the bacteria from
making a new cell wall. This means the bacteria grow larger but are unable to divide
in two. As a result they die.
3. Why does penicillin not affect animal cells?
© 2013 Education Services Australia Ltd, except where indicated otherwise. You may copy,
distribute and adapt this material free of charge for non-commercial educational purposes,
provided you retain all copyright notices and acknowledgements.
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