Molecular Genetics is one of the fast moving fields of science that has undergone a variable revolution over the last two decades leading to major advances in the understanding of gene structure and function at molecular level. Human Molecular Genetics is the study of the molecular basis of human genetic disease, developmental genetics, neurogenetics, chromosome structure and function, molecular aspects of cancer genetics, gene therapy, biochemical genetics, major advances in gene mapping and understanding of genome organization. Genetics is the study of how genes bring about characteristics, or traits, in living things and how those characteristics are inherited. Genes are portions of DNA molecules that determine characteristics of living things. Through the processes of meiosis and reproduction, genes are transmitted from one generation to the next. Heredity is a biological process where a parent passes certain genes onto their children or offspring. Genetics uses information from one or two genes to explain a disease or condition, whereas genomics examines all of the genetic information to determine biological markers predisposing an individual to disease. Genes are the best understood subsequence of DNA code. Most genes clearly encode the data sequence representing a particular protein. However, all of the genes together are only a small part of DNA code. The 30,000 odd genes in human DNA might only make up 4% of human DNA. This book presents a view in depth of the principal aspects of life science. Each chapter treats a discrete topic within the scope of biology and each is designed for students who are exposed to the topics for the first time. Since considerable ferment exists in the biological sciences today, it is increasingly important to keep pace with current developments.