genen

Genen, in biology, are the basic units of heredity. In organisms with DNA, genes are specific segments of the genome that carry instructions to make functional products—usually proteins or functional RNA molecules. The genome contains thousands of genes, numbered differently by species; in humans roughly 20,000 to 25,000 protein-coding genes, plus many noncoding genes. Genes are arranged on chromosomes and can be located throughout the genome. In Dutch, gen is the singular term and genen its plural.

Most genes include a coding region and regulatory elements such as promoters and enhancers that control when and where a gene is expressed. In eukaryotes, genes often have exons and introns; transcription produces RNA that is processed to mRNA or functional RNA. Gene expression is influenced by transcription factors, epigenetic marks, and environmental cues.

Genes are inherited in sets from parents; alleles provide variant sequences; patterns of inheritance can be Mendelian, polygenic, or influenced by epistasis and environment. Genetic variation arises through mutations, SNPs, gene duplications, and structural changes; some genes are organized in families.

Understanding genes enables diagnosis and treatment of diseases; gene therapy, genetic engineering and genome editing (e.g., CRISPR) are advancing medical and agricultural applications. The study of genes crosses biology, medicine, and ethics; ongoing research aims to map gene function and regulatory networks.