Assessment of Hereditary Influences
The following discussion assumes that the reader has taken a course in introductory and Mendelian genetics and has a basic understanding of its terminology, principles, and role in evolution. Briefly, within the nucleus of every cell except the gametes, most species have pairs of homologous chromosomes, each consisting of a long strand of the molecule deoxyribonucleic acid (DNA), with a centromere near one end. One chromosome of each pair is derived from the father and the other from the mother, and both contain the same gene sequence. Perhaps the most important discovery in biological science during the twentieth century, for which the 1962 Nobel Prize for Physiology or Medicine was awarded to Watson, Crick, and Wilkins, was the structure of DNA, a double helix consisting of two intertwined sugar-phosphate strands connected by a series of four bases, adenine pairing with thymine, and cytosine with guanine (Watson & Crick, 1953). This structure showed how chromosomes replicate themselves, and thereby the genetic code they contain, during cell division. Chromosomes consist of many genes, each being a section of chromosome at a specific locus that contains instructions for producing a particular protein that, together with others, helps to determine the development, structures, and physiological functions of the organism. In addition to the autosomes, there are two sex chromosomes that are heterologous in one sex, for example, XY in male mammals and WZ in female birds. Humans have 46 chromosomes, 22 pairs of homologous autosomes, together with a pair of sex chromosomes.
KeywordsInbred Strain Homologous Chromosome Royal Jelly Courtship Song Swiss Webster Mouse
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