Life is the chemistry that goes on inside every one of us. We seek to understand this chemistry, both the physical processes occurring at the molecular level and the chemical reactions, and we also seek to control the chemistry as a way to treat diseases. Biological Chemistry at Cambridge comprises several research groups with additional contributions from many more. The major themes are biological polymers, proteins and nucleic acids: How they interact with each other and with small molecules. How do proteins fold to a defined structure, and why do they sometimes not fold properly but aggregate, causing neurodegenerative diseases? How do proteins catalyse the reactions that they do and can we make small molecules that inhibit these processes? What structures can nucleic acids adopt? How can we detect them, and what is the role of modifications of individual nucleotides? How can we target medicinally active compounds to where they are needed in the body? By addressing these questions, we seek to improve human health and the treatment of diseases.