Genetics

Study sheds light on the darker parts of our genetic heritage

More than half of our genome consists of transposons,DNA sequences that are reminiscent of ancient, extinct viruses.Transposons are normally silenced by a process known as DNA methylation, but their activation can lead to ...

Genetics

Researchers report the function of reverse-twisting DNA

Normally, the two strands of the DNA double helix wind around each other in a right-handed spiral. However, there is another conformation called Z-DNA in which the strands twist to the left. The function of Z-DNA has remained ...

Diseases, Conditions, Syndromes

A near-fatal Valley Fever case opens doors to new treatment method

Of the 8,000 Californians who will contract Valley Fever this year, most will recover without treatment, and those with more serious cases will require an antifungal medication that clears the infection. But a few will experience ...

Genetics

Does genetic testing pose psychosocial risks?

For the last quarter century, researchers have been asking whether genetic information might have negative psychosocial effects. Anxiety, depression, disrupted relationships, and heightened stigmatization have all been posited ...

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Genome

In classical genetics, the genome of a diploid organism including eukarya refers to a full set of chromosomes or genes in a gamete; thereby, a regular somatic cell contains two full sets of genomes. In haploid organisms, including bacteria, archaea, viruses, and mitochondria, a cell contains only a single set of the genome, usually in a single circular or contiguous linear DNA (or RNA for retroviruses). In modern molecular biology the genome of an organism is its hereditary information encoded in DNA (or, for retroviruses, RNA).

The genome includes both the genes and the non-coding sequences of the DNA. The term was adapted in 1920 by Hans Winkler, Professor of Botany at the University of Hamburg, Germany. The Oxford English Dictionary suggests the name to be a portmanteau of the words gene and chromosome; however, many related -ome words already existed, such as biome and rhizome, forming a vocabulary into which genome fits systematically.

More precisely, the genome of an organism is a complete genetic sequence on one set of chromosomes; for example, one of the two sets that a diploid individual carries in every somatic cell. The term genome can be applied specifically to mean that stored on a complete set of nuclear DNA (i.e., the "nuclear genome") but can also be applied to that stored within organelles that contain their own DNA, as with the mitochondrial genome or the chloroplast genome. Additionally, the genome can comprise nonchromosomal genetic elements such as viruses, plasmids, and transposable elements. When people say that the genome of a sexually reproducing species has been "sequenced", typically they are referring to a determination of the sequences of one set of autosomes and one of each type of sex chromosome, which together represent both of the possible sexes. Even in species that exist in only one sex, what is described as "a genome sequence" may be a composite read from the chromosomes of various individuals. In general use, the phrase "genetic makeup" is sometimes used conversationally to mean the genome of a particular individual or organism. The study of the global properties of genomes of related organisms is usually referred to as genomics, which distinguishes it from genetics which generally studies the properties of single genes or groups of genes.

Both the number of base pairs and the number of genes vary widely from one species to another, and there is little connection between the two (an observation known as the C-value paradox). At present, the highest known number of genes is around 60,000, for the protozoan causing trichomoniasis (see List of sequenced eukaryotic genomes), almost three times as many as in the human genome.

An analogy to the human genome stored on DNA is that of instructions stored in a book:

This text uses material from Wikipedia, licensed under CC BY-SA