Genome

From ArticleWorld

The entire hereditary information in an organism is referred to as the genome. This information includes genes as well as the non-coding sequences in DNA. This word was developed by the use of portions of the terms gene and chromosome. The genome can also be considered to be a complete DNA sequence of one set of chromosomes.

Types

In most organisms more complex than viruses there is always the presence of additional genetic material other than that found in the chromosomes. This material is considered to be part of the genome in the sequencing of the genome of, for example, pathogenic microbes. In vertebrates however the genome is usually only considered to account for chromosomal DNA and not DNA found in organelles such as the mitochondria. Mitochondria are usually considered to possess their own genome.

Genetic variation

The genome often does not account for genetic diversity as it is usually only determined from half of the DNA of one cell from one individual. In order to determine genetic variations comparison is required among individuals. Thus genomes refer to a common term to describe a whole family of sequences and not to any particular DNA sequence. This concept is useful as individuals share commonalities in their sequences that can be used to establish linkages.

Evolution

Genomes in addition to being a summation of an organism's genetic material also possess traits that can be measured and studied. It is possible for researchers to compare traits like chromosome number, gene order and genome size as well as many other measurable factors. Processes such as duplication shape the genome and are necessary to the creation of genetic differences. Horizontal gene transfer explains how there is often extreme similarities between distantly related organisms.