Proteins are condensation polymers of amino acids. The structural formula of an amino acid is shown at the top left-hand corner of the picture above, where R is any chemical group. (Two amino acids, proline and hydroxyproline, are slightly different). In post 20.27 we met alanine – the amino acid in which -R is the… Continue reading 21.4 Proteins

I have used polar coordinates in a previous post. But that post contained mathematics that was more much difficult than is needed here. So, I am going to begin with a simple description of polar coordinates. Usually we describe the position of a point in space using Cartesian coordinates; in two dimensions the position of… Continue reading 21.3 Polar coordinates, circles and spirals

DNA is an example of a nucleic acid. Its name is an abbreviation for deoxyribonucleic acid. It was discovered in 1869 by a Swiss doctor called Friedrich Miescher (1844-1895). Most people know that DNA is responsible for coding genetic information but may not know much about its chemical composition, how it codes this information or… Continue reading 21.2 Nucleic acids