Gének

Gének are the basic units of heredity in living organisms. A gene is a discrete DNA sequence that contains the information necessary to produce a functional product, usually a protein or a molecule of RNA. Genes influence inherited traits and exist in multiple variants called alleles; the combination of alleles an individual carries contributes to its phenotype.

Genes are arranged on chromosomes and, in prokaryotes, may appear in operons; in eukaryotes they have a more complex structure, including promoters, exons and introns, and various regulatory elements that control when and where a gene is expressed. Gene expression proceeds in two main stages: transcription, where the DNA sequence is copied into RNA, and translation, where messenger RNA is used to synthesize a protein. Some genes encode noncoding RNAs with functional roles, such as ribosomal RNA or transfer RNA.

Regulation of gene activity is influenced by transcription factors, epigenetic marks (for example DNA methylation and histone modification), and chromatin structure. Genes can mutate or vary in sequence, producing alleles that contribute to genetic diversity, susceptibility to diseases, or variation in traits.

In contemporary biology, the study of genes occurs within the genome and gene networks, aided by sequencing technologies and comparative genomics. Gene editing technologies, notably CRISPR, provide means to alter specific genes, raising scientific and ethical discussions.