Dorothy Hodgkin looked at how atoms fit together into very complicated molecules. She used X-ray crystallography to find out what penicillin and insulin look like. Knowing what the molecules look like has helped other scientists understand how these molecules work, and to make new medicines.

Answers to quiz

In the middle ages what would someone put on an open cut?
Mouldy bread
Before anyone had thought about antibiotics, people had seen the benefits of mould, and used it - sometimes successfully - to heal wounds.

Which piece of mouldy fruit was important in the mass production of penicillin?
Cantaloupe melon
A cantaloupe found at a local market had a very strong strain of penicillin growing on it.  This was the strain used in the first mass-produced penicillin.

Penicillin works by weakening which part of the bacterium?
Cell wall
Penicillin stops the bacteria from making cell walls, which surround and protect bacteria.  Without this ability the bacteria wall become weak and the bacteria cannot reproduce.

Streptomycin was the second antibiotic to be discovered.  What did it come from?
It is bizarre, but this really useful antibiotic comes from bacteria.

Before the discovery of streptomycin, what did doctors use to treat tuberculosis?
Research shows that there may be a link between vitamin D and tuberculosis, with doses of the vitamin reducing the severity of the disease.

Which of these infections can be cured with penicillin?
MRSA is resistant to many antibiotics, including penicillin.  Polio is a virus.

What mass of 'good' bacteria do we normally carry around in our intestines?

Curriculum Links

Saving lives

Working scientifically

Scientific attitudes

  • understand that scientific methods and theories develop as earlier explanations and are modified to take account of new evidence and ideas, together with the importance of publishing results and peer review
  • Challenges for Britain, Europe and the wider world 1901 to the present day.

Scottish Curriculum Links



SCN 3-13b

Biological systems - Body systems and cells

I have contributed to investigations into the different types of microorganisms and can explain how their growth can be controlled.


SCN 3-13c

Biological systems - Body systems and cells

I have explored how the body defends itself against disease and can describe how vaccines can provide protection.


TCH 3-01a

Technological developments in society


TCH 3-04a

ICT to enhance learning

I enhance my learning by applying my ICT skills in different learning contexts across the curriculum


TCH 4-03b

ICT to enhance learning

I can use ICT effectively in different learning contexts across the curriculum to access, select and present relevant information in a range of tasks.


TCH 4-04a

ICT to enhance learning

Throughout my learning, I can make effective use of a computer system to process and organise information.

Saving lives

Starting in 1934, Dorothy Hodgkin worked out the structure of many molecules.  She helped confirm the structure of pepsin, which is an enzyme found in the stomach that helps break down food like meat and eggs.  Soon after this she worked out what cholesterol - another biological molecule - looked like.

Penicillin growing in petri dish

In 1945, two years after being given penicillin crystals, Dorothy Hodgkin determined the structure of this molecule.  People already knew that penicillin was an important natural antibiotic, for treating bacterial infections. Finding out the structure of the penicillin molecule was a key step in making artificial antibiotics.

Dorothy Hodgkin also determined the shape of vitamin B12 in 1954.  A lack of vitamin B12 causes anaemia, where the body cannot produce enough red blood cells.  Dorothy Hodgkin received the Nobel Prize in 1964 for these two discoveries.

Key fact: Dorothy Hodgkin's work with molecules and crystals had important uses for improving medical treatment.

Scientist studying penicillinWhy is knowing the shape so important?

Penicillin was discovered by accident, by Alexander Fleming in 1928.  He spotted a petri dish of bacteria had been infected with a penicillin mould.  He identified that it was the mould that was killing the bacteria, and very quickly after this, life-threatening illnesses were able to be cured, at least for the lucky few.

Waiting for the mould to grow was slow.  However, Howard Florey and Ernst Chain managed to get a strong strain of the mould to grow more quickly, using a type of sugar and oxygen to feed it.  By the 1940s penicillin was being mass produced.

Have a look at Trailblazing - 1940:

In 1945, Dorothy Hodgkin discovered the structure of penicillin.  This led to scientists understanding how this antibiotic worked, and was the first step towards creating other similar antibiotics.



Key fact: If you understand the shape of molecules, you can apply this knowledge to creating new, artificial molecules, such as a new type of drug.



How much do you know about antibiotics?

Take the online quiz here,

or download the pdf worksheet.