The science of biological inheritance, that is, the causes of the resemblances and differences among related individuals. Genetics occupies a central position in biology, for essentially the same principles apply to all animals and plants, and understanding of inheritance is basic for the study of evolution and for the improvement of cultivated plants and domestic animals. It has also been found that genetics has much to contribute to the study of embryology, biochemistry, pathology, anthropology, and other subjects. Genetics may also be defined as the science that deals with the nature and behavior of the genes, the fundamental hereditary units. From this point of view, evolution is seen as the study of changes in the gene composition of populations, whereas embryology is the study of the effects of the genes on the development of the organism. Population genetics The field of molecular genetics describes the basis of inheritance at the molecular level. It focuses on two general questions: how do genes specify the structure and function of organisms, and how are genes replicated and transmitted to successive generations? Both questions have been answered. Genes specify organismal structure and function according to a process described by the central dogma of molecular biology: DNA is made into messenger ribonucleic acid (mRNA), which specifies the structure of a protein; the mRNA molecule then serves as a template for protein synthesis, which is carried out by complex machinery that comprises a particle called a ribosome and special adapter RNA molecules called transfer RNA. The structure of DNA provides a simple mechanism for genes to be faithfully reproduced: the specific interaction between the nucleotides means that each strand of the double helix carries the information for producing the other strand.Genetic code Genetic engineering Mutation | 
