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(A), guanine (G), cytosine (C), and thymine (T). Genes make up sections of the DNA double helix, and each gene has hun- dreds or thousands of bases in sequence, so it can carry a huge amount of information. The whole set of human genes has 3.1 billion pairs of bases. For a gene to work, the order of its bases is copied into another substance very similar to DNA, called ribonucleic acid (RNA). The RNA then goes to another place inside the cell, where it carries out its job, almost like a person in a factory. It gathers together various substances or raw materials and fixes them together in the right order, following the instructions in

Cell, Chromosome, DNA and gene. A gene is a length of DNA that codes for a specific protein, and is contained in the chromosomes that are part of each cell.

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Introduction to Genetics