Genetics

Genetics is a branch of biology that studies genes, heredity, and variation among living organisms. It examines how biological information is stored in cells and passed from parents to offspring, and how that information affects the organism's physical form, cellular function, and behavior.

The foundation of this science is DNA (deoxyribonucleic acid), a long molecule composed of a chain of small units called nucleotides. The sequence of these units forms the code for building proteins. A section of DNA that defines a single function is called a gene. In most living organisms, DNA is organized into structures called chromosomes.

History and foundations

Modern genetics is rooted in the experiments of Gregor Mendel on pea plants, conducted in the 19th century. Mendel discovered that traits are inherited in distinct, non-blending portions, which led to the laws of heredity. His work was recognized at the beginning of the 20th century, after which the field grew rapidly. During the 20th century, the structure of DNA's two intertwined strands was elucidated, explaining how information is copied.

Key terminology

An allele is a variant form of a single gene. Genotype is the collection of genes an organism carries, while phenotype is the observable characteristic, such as eye color or height. Some traits are dominant, while others are recessive and appear only when both alleles are identical. Changes in the DNA sequence are called mutations; some are harmless, while others affect health.

Fields

Molecular genetics examines how DNA is read and converted into proteins. Population genetics measures how alleles vary within large groups over time and underlies evolutionary theory. Genomics studies all genes in an organism at once. Medical genetics addresses inherited diseases and family screening.

Applications

Genetics is used in agriculture and animal husbandry to select varieties with higher yields or disease resistance. In medicine, it enables identification of inherited diseases and points to personalized treatment. DNA analysis is also used in individual identification and kinship tracing. Each application of genetic technology raises ethical and legal questions that governments define.