1.2.1 The human genome: chromosomes and genes

Almost all of the different types of cell in an individual contain the same genetic material in the chromosomes, as a consequence of mitosis. You had a glimpse of the appearance of the 46 human chromosomes in Figure 1.1, and in this course we examine their size, shape and genetic composition.

Chromosomes can be regarded as strings of genes arranged along their length, rather like beads on a thread. Each gene consists of a short section of the DNA that runs the full length of each chromosome. Genes direct our characters, such as eye colour, and also the processes that go on inside us, from the small-scale processes of cell division to the large-scale processes of development and reproduction.