genetics

Genetics is the branch of biology that studies heredity and variation in organisms. It examines how traits are transmitted from one generation to the next, and how genetic material influences development, physiology, and biology. The central unit of heredity is the gene, located on chromosomes in cells.

Genes are units of heredity that come in alternative forms called alleles. In sexually reproducing organisms, offspring inherit two alleles for each gene, one from each parent. Mendel's early work established fundamental patterns of inheritance, later expanded by knowledge of chromosomes and DNA.

DNA carries genetic information in sequences of nucleotides. The structure of DNA, discovered in 1953, revealed how genetic instructions are stored and replicated. The central dogma describes transcription of DNA into RNA and translation of RNA into proteins, the workhorses that execute cellular functions.

Genetics also includes non-Mendelian patterns of inheritance, gene linkage and recombination, and the regulation of gene expression. Epigenetics studies heritable changes in gene activity not caused by DNA sequence, such as chemical modifications that alter chromatin structure. Genetic variation arises from mutation, recombination, and migration.

Applications span medicine, agriculture, forensics, and conservation. Genetic testing and genome sequencing inform diagnosis and personalized therapy; gene editing and therapy aim to treat disease. Ethical, legal, and social considerations guide research and data privacy in genetic information.