Introduction

Every living thing is built from biomolecules -- carbohydrates, proteins, lipids and nucleic acids -- assembled from just five major elements: carbon, hydrogen, oxygen, nitrogen and phosphorus. These molecules do far more than provide structure: they are also the fuel that powers every function of a living system, from muscle contraction to thought. The branch of chemistry that studies the chemical processes behind biology is called biochemistry, and this unit is your first serious introduction to it.

What this unit sets out to do. By the end of it you should be able to:

• describe the importance of carbohydrates and how they are classified by structure and function;
• explain the structure of glucose and fructose, and how those structures were worked out;
• list the twenty amino acids, and explain how the peptide bond forms;
• explain the four levels of protein structure;
• outline the mechanism of enzyme catalysis;
• summarise the sources of vitamins and the diseases their deficiency causes;
• outline the composition and structure of nucleic acids, differentiate RNA from DNA, and explain DNA fingerprinting;
• appreciate the importance of biomolecules in everyday life.