Concepts Summary

• Genetics is central to the life of every person: it influences a person’s physical features, personality, intelligence, and susceptibility to numerous diseases.
• Genetics plays important roles in agriculture, the pharmaceutical industry, and medicine. It is central to the study of biology.
• All organisms use similar genetic systems. Genetic variation is the foundation of evolution and is critical to understanding all life.
• The study of genetics can be broadly divided into transmission genetics, molecular genetics, and population genetics.
• Model genetic organisms are species about which much genetic information exists because they have characteristics that make them particularly amenable to genetic analysis.
• The use of genetics by humans began with the domestication of plants and animals.
• Ancient Greeks developed the concepts of pangenesis and the inheritance of acquired characteristics, both of which were later disproven. Ancient Romans developed practical measures for the breeding of plants and animals.
• Preformationism suggested that a person inherits all of his or her traits from one parent. Blending inheritance proposed that offspring possess a mixture of the parental traits. These ideas were later shown to be incorrect.
• By studying the offspring of crosses between varieties of peas, Gregor Mendel discovered the principles of heredity. Developments in cytology in the nineteenth century led to the understanding that the cell nucleus is the site of heredity.
• In 1900, Mendel’s principles of heredity were rediscovered. Population genetics was established in the early 1930s, followed closely by biochemical genetics and bacterial and viral genetics. The structure of DNA was discovered in 1953, stimulating the rise of molecular genetics.
• Cells are of two basic types: prokaryotic and eukaryotic.
• The genes that determine a trait are termed the genotype; the trait that they produce is the phenotype.
• Genes are located on chromosomes, which are made up of nucleic acids and proteins and are partitioned into daughter cells through the process of mitosis or meiosis.
• Genetic information is expressed through the transfer of information from DNA to RNA to proteins.
• Evolution requires genetic change in populations.