Gene
From WikiLectures
A gene is the basic unit of genetic information (the basic unit of heredity). It is a certain stretch of DNA (sequence of nucleotides) on a chromozome.
General characteristics of the gene[edit | edit source]
- a gene can occur in different forms – alleles
- we refer to the set of all alleles in the cell of a given individual as genotype
- the set of all the DNA of a given organism is called the genome
- the human genome consists of a nuclear genome and an extranuclear genome (mitochondrial)
- genes are arranged linearly on chromosomes and their specific location (locus) is unchanging
- all genes on one chromosome form a linkage group
- it includes so-called exons and intrones (cut out during DNA editing)
Gene species[edit | edit source]
- genes can be divided into two basic groups according to function:
- Structural genes – encode the primary structure of proteins, such as proteins with a biochemical, physiological or structural function
- Genes for functional RNAs – their products, unlike structural genes, are not translated.
- They are mainly genes for tRNA and rRNA (more about tRNA and rRNA on the RNA page).
Gene function[edit | edit source]
- one gene can condition the creation of one specific trait (monogenic inheritance )
- the determination of one trait by one gene occurs more rarely than the realization of a trait after the interaction of a larger number of genes (oligogenic, or polygenic inheritance)
- more often, the formation of a trait depends on gene interactions, i.e. the specific form of the trait is determined by the alleles of several participating genes
- another example of the multifacetedness of genetic information is the so-called gene families – gene family is a group of genes with a similar sequence that have the same or similar biological function
