3.1 Amino Acids 75 acids, covalently linked in characteristic linear sequences 3.2 Peptides and Proteins 85 Because each of these amino acids has a side chain with 3.3 Working with Proteins 89 distinctive chemical properties, this group of 20 pre cursor molecules may be regarded as the alphabet in
A conditional sentence (or \conditional\ for short) is commonly composed of two parts: conditional clause main clause. Despite the many possible sequences of verb forms in conditionals, the following four types represent perhaps the commonest and the most useful ones:
