genome

Article

May 20, 2022

Genome (German: Genom, English: genome, Genome) is a vocabulary derived from German that means "whole / total genetic information", and as a more specific / limited meaning / usage, it is currently widely used. There are the following two separately. From the standpoint of classical genetics, the genome in a diploid organism refers to the entire chromosome or gene contained in the germ cell, so it is considered that there are two sets of genomes in the somatic cell. In monoploid organisms such as prokaryotic organisms, intracellular organs, and viruses, it refers to all genetic information on DNA (RNA in some viruses and viroids). From the standpoint of molecular biology, the genome is the genetic information on all nucleic acids of a certain organism, based on the idea that all organisms should be treated in a unified manner. However, in the case of eukaryotes, the genomes of organelles (mitochondria, chloroplasts, etc.) are treated independently (the human genome does not include the human mitochondrial genome). The genome is roughly divided into a coding region that encodes a protein and a non-coding region other than that. At the beginning of genome decoding, it was known that a part of the non-coding region was involved in gene expression regulation, but most of it was considered to be meaningless and was also called junk DNA. As of 2020, it has been clarified that this region contains a large amount of information that RNA genes are essential for biological functions in addition to gene expression regulation.

Definition

In classical genetics, it is defined as "genetic information essential for making an organism into that organism." It is a coined word that combines the gene "gene" and the chromosome "chromosome" or gene (gene) + -ome (total (ohm)) genome (genome), and was a botanist at the University of Hamburg, Germany in 1920. Built by Hans Winkler. The first definition by H. Winkler meant "the chromosomal set of a gamete (germ cell)", but in 1930 it was defined by Hitoshi Kihara as "the minimum set of chromosomes essential to make an organism into that organism". It was redone. Kihara proposed this genomic theory based on the observation of ploidy of wheat chromosomes. Both definitions represent all chromosomes (or their genetic information) contained in germ cells, and it is considered that N sets of genomes exist in somatic cells of N-ploid organisms. Since the discovery of DNA in 1956, it also has the meaning of "the entire base sequence of DNA that constitutes all chromosomes."

Genome analysis

Genome analysis is a method for clarifying the genomic composition of polyploid species at the chromosomal level. Mating a polyploid species with its parent species, observing chromosomal synapsis at the first F1 meiosis of the hybrid, and calculating the degree of genomic homology. Mainly in plants, polyploidy may be seen in which three or more sets of genomes, which are the basic units of life support, exist in one cell. Genome analysis showed that the bread wheat, which was the basis of Kihara's genome theory, is a hexaploid in which two sets of three types of genomes are combined.

Genome sequence analysis and functional mapping

Since the 1990s, a genome project aimed at decoding the entire base sequence of the genome has been carried out for various species (it was the genome sequencing that was completed, and the decoding of the contents has not been completed. Therefore, it is also called a genome sequencing project or a genome sequencing project, not a "genome project"). Elucidation of whole genome information is the life manifestation by comprehensive analysis.