Genome size refers to the total amount of DNA contained within one copy of a genome. It is typically measured in terms of mass (in picograms, or trillionths [10^-12] of a gram [abbreviated pg], or less frequently in Daltons) or as the total number of nucleotide base pairs (typically in millions of base pairs, or megabases [abbreviated Mb or Mbp]). One picogram (pg) equals 978 megabases (Mb) (Dolezel et al. 2003). In diploid organisms, genome size is used interchangeably with the term C-value. Jump to: navigation, search Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and most viruses). ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Jump to: navigation, search Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ... The gram or gramme, symbol g, is a unit of mass, and is defined as one one-thousandth of the SI base unit kilogram (i. ... The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... A nucleotide is a monomer or the structural unit of nucleotide chains forming nucleic acids as RNA and DNA. A nucleotide consists of a heterocyclic nucleobase, a pentose sugar (ribose or deoxiribose), and a phosphate or polyphosphate group. ... In genetics, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). ... Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... In biology and ecology, an organism (in Greek organon = instrument) is a living being. ... // Definition The term C-value refers to the amount of DNA contained within a haploid nucleus (e. ...

Origin of the term

The term "genome size" is often erroneously attributed to Hinegardner (1976), even in discussions dealing specifically with terminology in this area of research (e.g., Greilhuber et al. 2005). Notably, Hinegardner (1976) used the term only once: in the title. The term actually seems to have first appeared in 1968 when Hinegardner wondered, in the last paragraph of his article, whether "cellular DNA content does, in fact, reflect genome size". In this context, "genome size" was being used in the sense of genotype to mean the number of genes. In a paper submitted only two months later (in February of 1969), Wolf et al. (1969) used the term "genome size" throughout and in its present usage; therefore these authors should probably be credited with originating the term in its modern sense. By the early 1970s, "genome size" was in common usage with its present definition, probably as a result of its inclusion in Ohno’s influential book Evolution by Gene Duplication, published in 1970. Jump to: navigation, search Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ...

Variation in genome size

The genome sizes of thousands of eukaryotes have been analyzed over the past 50 years, and these data are available in online databases for animals, plants, and fungi (see external links). Nuclear genome size is typically measured in eukaryotes using either densitometric measurements of Feulgen-stained nuclei (previously using specialized densitometers, now more commonly using computerized image analysis; Hardie et al. 2002) or flow cytometry. In prokaryotes, pulsed-field gel electrophoresis and complete genome sequencing are the predominant methods of genome size determination. Nuclear genome sizes are well known to vary enormously among eukaryotic species. In animals they range more than 3,300-fold, and in land plants they differ by a factor of about 1,000 (Bennett and Leitch 2005; Gregory 2005). Protist genomes have been reported to vary more than 300,000-fold in size, but the high end of this range (Amoeba) has been called into question. In eukaryotes (but not prokaryotes), variation in genome size bears no relationship to the number of genes, an observation that was deemed wholly counterintuitive before the discovery of non-coding DNA and which became known as the C-value paradox as a result. However, although there is no longer any paradoxical aspect to the discrepancy between genome size and gene number, this term remains in common usage. For reasons of conceptual clarification, the various puzzles that remain with regard to genome size variation instead have been suggested to more accurately comprise a complex but clearly defined puzzle known as the C-value enigma. Genome size correlates with a range of features at the cell and organism levels, including cell size, cell division rate, and, depending on the taxon, body size, metabolic rate, developmental rate, organ complexity, geographical distribution, and/or extinction risk (for recent reviews, see Bennett and Leitch 2005; Gregory 2005). Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Principle of spot light densitometry Densitometry is the quantitative measurement of optic density in light-sensitive materials, such as photographic film, due to exposure to light. ... Jump to: navigation, search German doctor credited with the isolation of DNA; also developed the Feulgen stain to identify genetic material. ... Image analysis is the extraction of useful information from images; mainly from digital images by means of digital image processing techniques. ... Jump to: navigation, search Flow cytometry is a technique for counting, examining and sorting microscopic particles suspended in a stream of fluid. ... Prokaryotes are unicellular (in rare cases, multicellular) organisms without a nucleus. ... In genetics and biochemistry, sequencing means to determine the primary structure (or primary sequence) of an unbranched biopolymer. ... Jump to: navigation, search Typical phyla Rhodophyta (red algae) Chromista Heterokontophyta (heterokonts) Haptophyta Cryptophyta (cryptomonads) Alveolates Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavates Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Amoebozoa Choanozoa Many others; classification varies Protists are a heterogeneous group of living things, comprising those eukaryotes that are neither animals, plants... Amoeba is a genus of protozoa that moves by means of temporary projections called pseudopods, and is well-known as a representative unicellular organism. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... In genetics, noncoding DNA describes DNA which does not contain instructions for making proteins (or other cell products such as RNAs). ... // Definition The C-value paradox is a term used to describe the discrepancy between nuclear genome size and the number of genes among eukaryotic species. ... Jump to: navigation, search Listen to this article · (info) This audio file was created from the revision dated 2005-07-07, and does not reflect subsequent edits to the article. ... // Definition and origin The C-value enigma is a term used to describe the complex puzzle surrounding the extensive variation in nuclear genome size among eukaryotic species. ... Jump to: navigation, search Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... Cell division is the process by which a cell (called the parent cell) divides into two cells (called daughter cells). ... A taxon (plural taxa) is an element of a taxonomy, e. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste... In biology, an organ (Latin: organum, instrument, tool) is a group of tissues, which perform a specific function or group of functions. ... Jump to: navigation, search In biology and ecology, extinction is the ceasing of existence of a species or group of taxons. ...

References

Bennett, M.D. and I.J. Leitch. 2005. Genome size evolution in plants. In The Evolution of the Genome (ed. T.R. Gregory), pp. 89-162. Elsevier, San Diego. // Summary The Evolution of the Genome is a book edited by Dr. T. Ryan Gregory of the University of Guelph, Ontario, Canada, covering a wide range of topics in the study of genome evolution. ...

Doležel, J., J. Bartoš, H. Voglmayr, and J. Greilhuber. 2003. Nuclear DNA content and genome size of trout and human. Cytometry 51A: 127-128.

Gregory, T.R. 2005. Genome size evolution in animals. In The Evolution of the Genome (ed. T.R. Gregory), pp. 3-87. Elsevier, San Diego. // Summary The Evolution of the Genome is a book edited by Dr. T. Ryan Gregory of the University of Guelph, Ontario, Canada, covering a wide range of topics in the study of genome evolution. ...

Greilhuber, J., J. Doležel, M. Lysak, and M.D. Bennett. 2005. The origin, evolution and proposed stabilization of the terms 'genome size' and 'C-value' to describe nuclear DNA contents. Annals of Botany 95: 255-260.

Hardie, D.C., T.R. Gregory, and P.D.N. Hebert. 2002. From pixels to picograms: a beginners' guide to genome quantification by Feulgen image analysis densitometry. Journal of Histochemistry and Cytochemistry 50: 735-749.

Hinegardner, R. 1968. Evolution of cellular DNA content in teleost fishes. American Naturalist 102: 517-523.

Hinegardner, R. 1976. Evolution of genome size. In Molecular Evolution (ed. F.J. Ayala), pp. 179-199. Sinauer Associates, Inc., Sunderland.

Ohno, S. 1970. Evolution by Gene Duplication. Springer-Verlag, New York.

Wolf, U., H. Ritter, N.B. Atkin, and S. Ohno. 1969. Polyploidization in the fish family Cyprinidae, Order Cypriniformes. I. DNA-content and chromosome sets in various species of Cyprinidae. Humangenetik 7: 240-244.

See also

• Animal Genome Size Database
• Cell nucleus
• Comparative genomics
• C-value
• C-value enigma
• C-value paradox
• Genome
• Human genome
• Junk DNA
• Noncoding DNA
• Plant DNA C-values Database
• Selfish DNA
• Transposable elements

The Animal Genome Size Database is a comprehensive catalogue of published genome size estimates for vertebrate and invertebrate animals. ... Jump to: navigation, search In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is found in all eukaryotic cells that contains most of the cells genetic material. ... // Overview Comparative genomics is the study of relationships between the genomes of different species. ... // Definition The term C-value refers to the amount of DNA contained within a haploid nucleus (e. ... // Definition and origin The C-value enigma is a term used to describe the complex puzzle surrounding the extensive variation in nuclear genome size among eukaryotic species. ... // Definition The C-value paradox is a term used to describe the discrepancy between nuclear genome size and the number of genes among eukaryotic species. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... The human genome is the genome of Homo sapiens. ... In molecular biology, junk DNA is a collective label for the portions of the DNA sequence of a chromosome or a genome for which no function has been identified. ... In genetics, noncoding DNA describes DNA which does not contain instructions for making proteins (or other cell products such as RNAs). ... Description The Plant DNA C-values Database is a comprehensive catalogue of C-value (nuclear DNA content, or in diploids, genome size) data for land plants and algae. ... Selfish DNA is DNA which is prevalent in the genome, not because its phenotypic effect is beneficial, but because it has properties which cause the number of copies of it within the genome to increase with time. ... Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called Transposition. ...

External links

• Animal Genome Size Database
• Plant DNA C-values Database
• Fungal Genome Size Database