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.

The Protein Data Bank is a huge online library of large biological molecules.  Data has been gathered from a number of techniques, including X-ray crystallography, to produce the information in the database:
Click on Molecule of the Month for loads of background information.

A - Cold virus

B - Amylase


D - Dengue virus

E - Prion


F - Insulin

Curriculum Links

Microscopic world

Working scientifically

Scientific attitudes

  • understand that scientific methods and theories develop as earlier explanations are modified to take account of new evidence and ideas, together with the importance of publishing results and peer review

Scottish Curriculum Links:


SCN 3-12b

Biological systems - Body systems and cells


SCN 4-15a

Materials - Properties and uses of substances


SCN 4-20a

Topical Science


TCH 3-01a

Technological developments in society

Microscopic world


X-ray crystallography has an enormous number of uses today.  Pharmaceutical companies (companies that make drugs for use in medicine) use X-ray crystallography to find out what biological molecules are causing a disease, and how they attack the body.  They will then look for other molecules to stop this attack.

With advances in computing, and ever more powerful sources of X-rays, scientists are using X-ray crystallography alongside other techniques to look at viruses.  Knowing what a virus looks like is one of the first steps to understanding how they work.  Scientists may be able to find out why viruses mutate (change their structure) over time and why these changes stop our immune systems from recognising the same virus each time.

Key fact: X-ray crystallography is still used today, and the information scientists discover about molecules from using it is very important for helping to treat all kinds of diseases.



What do these really big biological molecules look like?  Can you guess the molecule?  Match the pictures with the description......

Take the quiz online here,

or download the pdf worksheet.