- Phenotypic trait
A trait is a distinct variant of a phenotypic character of an organism that may be inherited, environmentally determined or be a combination of the two. For example, eye color is a character or abstraction of an attribute, while blue, brown and hazel are traits.
A phenotypic trait is an obvious and observable trait; it is the expression of genes in an observable way. An example of a phenotypic trait is hair color, there are underlying genes that control the hair color, which make up the genotype, but the actual hair color, the part we see, is the phenotype. The phenotype is the physical characteristics of the organism. The phenotype is controlled by the genetic make-up of the organism and the environmental pressures the organism is subject to. 
A trait may be any single feature or quantifiable measurement of an organism. However, the most useful traits for genetic analysis are present in different forms in different individuals.
A visible trait is the final product of many molecular and biochemical processes. In most cases, information starts with DNA traveling to RNA and finally to protein (ultimately affecting organism structure and function). This is the central dogma of molecular biology as stated by Francis Crick.
This information flow may also be followed through the cell as it travels from the DNA in the nucleus, to the cytoplasm, to the ribosomes and the endoplasmic reticulum, and finally to the Golgi apparatus, which may package the final products for export outside the cell.
Genetic origin of traits in diploid organisms
The heritable unit that may influence a trait is called a gene. A gene is a portion of a chromosome. An important reference point along a chromosome, which is a very long and compacted string of DNA, is the centromere; the distance from a gene to the centromere is referred to as the gene's locus or map location. A chromosomal region known to control a trait while the responsible gene within not being identified is referred to as a quantitative trait locus.
Mendelian expression of genes in diploid organisms
Combinations of different alleles thus go on to generate different traits through the information flow charted above. For example, if the alleles on homologous chromosomes exhibit a "simple dominance" relationship, the trait of the "dominant" allele shows in the phenotype.
Gregor Mendel pioneered modern genetics. His most famous analyses were based on clear-cut traits with simple dominance. He determined that the heritable units, what he called "genes", occurred in pairs and could exhibit linkage. His tool was statistics: long before the molecular model of DNA was introduced by James D. Watson and Francis Crick.
He is also known to have 'cheated' on his experiments, removing outliers and generally 'tidying' datasets - statistics, and repeating the experiments, shows that his results were just 'too perfect', a point first noted by the Godfather of statistics, RA Fisher, in 1936: http://www.cs.brown.edu/courses/csci1950-l/presentations/REVISED--AFCB%202007%20Course%20Fisher%20and%20Mendel.ppt
Biochemistry of dominance and extensions to expression of traits
Extended expression patterns seen in diploid organisms include facets of incomplete dominance, codominance, and multiple alleles.
The development of phenotype Key concepts Genetic architecture Non-genetic influences Developmental architecture Evolution of genetic systems Influential figures Debates List of evolutionary biology topics
- Lawrence>Lawrence, Eleanor (2005) Henderson's Dictionary of Biology. Pearson, Prentice Hall. ISBN 0-13-127384-1
- Campbell, Neil; Reece, Jane (March 2011) , "14", Biology (Sixth ed.), Benjamin Cummings
Wikimedia Foundation. 2010.
См. также в других словарях:
Trait — In genetics, a trait refers to any genetically determined characteristic. In technical terms, a genetic trait is amenable to segregation analysis rather than quantitative analysis. A dominant lethal trait is a trait that is expressed if present… … Medical dictionary
Trait (biology) — A trait is a distinct phenotypic character of an organism that may be inherited, environmentally determined or somewhere in between.Lawrence, Eleanor (2005) Henderson s Dictionary of Biology . Pearson, Prentice Hall. ISBN 0 13 127384 1] For… … Wikipedia
Trait theory — In psychology, Trait theory is a major approach to the study of human personality. Trait theorists are primarily interested in the measurement of traits , which can be defined as habitual patterns of behavior, thought, and emotion. [Saul Kassin,… … Wikipedia
Quantitative trait locus — See also: Epistasis Quantitative traits refer to phenotypes (characteristics) that vary in degree and can be attributed to polygenic effects, i.e., product of two or more genes, and their environment. Quantitative trait loci (QTLs) are stretches… … Wikipedia
Mapping of quantitative trait loci — Quantitative traits refer to the traits whose phenotypic characteristics vary in degree and can be attributed to the interactions between two or more genes and their environment. Though not necessarily genes themselves, quantitative trait loci… … Wikipedia
Quantitative genetics — Part of a series on Genetics Key components Chromosome DNA • RNA Genome Heredity Mutation Nucleotide Variation … Wikipedia
Natural selection — For other uses, see Natural Selection (disambiguation). Part of a series on Evolutionary Biology … Wikipedia
Norms of reaction — In ecology and genetics, a norm of reaction describes the pattern of phenotypic expression of a single genotype across a range of environments. One use of norms of reaction is in describing how different species especially related species respond … Wikipedia
Phylogenetic comparative methods — When applied to comparative data, conventional statistical methods assume, in effect, that all species are completely unrelated. As if they descended from a big bang of special creation. Such a scenario can be depicted as a star phylogeny (left) … Wikipedia
Media naturalness theory — was developed by Ned Kock. This theory is sometimes referred to as the psychobiological model, or compensatory adaptation theory. It has been used to understand human behavior toward technology in various contexts, such as: education,… … Wikipedia