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The lemon, like many other cultivated Citrus species, is a hybrid, in its case of the citron and the bitter orange. [5] [6] The lemon is a hybrid of the citron and the bitter orange. [6] Taxonomic illustration by Franz Eugen Köhler, 1897 . Lemons were most likely first grown in northeast India. [7] The origin of the word lemon may be Middle ...
The information within a particular gene is not always exactly the same between one organism and another, so different copies of a gene do not always give exactly the same instructions. Each unique form of a single gene is called an allele. As an example, one allele for the gene for hair color could instruct the body to produce much pigment ...
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
Gene nomenclature was established by the HUGO Gene Nomenclature Committee (HGNC), a committee of the Human Genome Organisation, for each known human gene in the form of an approved gene name and symbol (short-form abbreviation), which can be accessed through a database maintained by HGNC. Symbols are chosen to be unique, and each gene has only ...
Genetic engineering has been used to produce proteins derived from humans and other sources in organisms that normally cannot synthesize these proteins. Human insulin-synthesising bacteria were developed in 1979 and were first used as a treatment in 1982. [58] In 1988 the first human antibodies were produced in plants. [59]
A null allele is a gene variant that lacks the gene's normal function because it either is not expressed, or the expressed protein is inactive. For example, at the gene locus for the ABO blood type carbohydrate antigens in humans, [13] classical genetics recognizes three alleles, I A, I B, and i, which determine compatibility of blood transfusions.
An organism that has two different alleles for a gene is said to be heterozygous for that gene (and is called a heterozygote). Mendel hypothesized that allele pairs separate randomly, or segregate, from each other during the production of the gametes in the seed plant ( egg cell ) and the pollen plant ( sperm ).
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.