Free Download A Molecular Approach by Terry Brown

A Molecular Approach by Terry Brown

Genetics is the study of heredity, the process by which characteristics are passed from parents to offspring so that all organisms, human beings included, resemble their ancestors. The central concept of genetics is that heredity is controlled by a vast number of factors, called genes, which are physical particles present inside living cells. Genes are units of biological information. The entire complement of genes in an organism contains the total amount of information needed to construct a living, functioning example of that organism. Some genes are responsible for the visible characteristics of the organism, such as eye color in humans. Other genes are responsible for biochemical activities that are discernible only when the physiology of the organism is examined. Often, we become aware of the function of such genes only when they fail to work properly. An example is the human gene CFTR, which contains part of the biological information for transport of chloride ions into and out of cells. If the CFTR gene is defective, then chloride transport breaks down, leading to inflammation and mucus accumulation in the lungs. These are the primary symptoms of the disease called cystic fibrosis, and it was through study of the underlying cause of cystic fibrosis that the CFTR gene was first discovered. CFTR in fact stands for “cystic fibrosis transmembrane regulator,” a term describing the biological information contained in this gene. Because genes are units of biological information they are also units of inheritance. During sexual reproduction, genes of the parents are incorporated into the fertilized egg cell. These genes provide the fertilized egg with the full complement of biological information that it needs in order to develop into a new living organism. This new organism therefore inherits physical and biochemical characteristics from both its parents. An understanding of genetics therefore requires an understanding of genes. The purpose of this book is to help you to acquire that understanding.