Geno Pheno Talk:
"I wanted to get a little into talking about the different characteristics within a strain. These variations are known as Genotypes and Phenotypes. I am going to do a cut and past from Wikipedia to give folks a definition of the term without having to leave this thread to catch up."
Phenotype
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For a non-technical introduction to the topic, see
Introduction to genetics.
Individuals in the
mollusk species
Donax variabilis show diverse coloration and patterning in their phenotypes.
A
phenotype is any
observable characteristic or
trait of an
organism: such as its
morphology,
development, biochemical or physiological properties, or
behavior. Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and possible interactions between the two. The
genotype of an organism is the inherited instructions it carries within its genetic code. Not all organisms with the same genotype look or act the same way, because appearance and behavior are modified by environmental and developmental conditions. Similarly, not all organisms that look alike necessarily have the same genotype. This
genotype-phenotype distinction was proposed by
Wilhelm Johannsen in 1911 to make clear the difference between an organism's
heredity and what that heredity produces.
[1][2] The distinction is similar to that proposed by
August Weismann, who distinguished between
germ plasm (heredity) and
somatic cells (the body). A more modern version is
Francis Crick's
Central dogma of molecular biology.
Despite its seemingly straightforward definition, the concept of the phenotype has some hidden subtleties. First, most of the molecules and structures coded by the genetic material are not visible in the appearance of an organism, yet they are observable (for example by
Western blotting) and are thus part of the phenotype. Human
blood groups are an example. So, by extension, the term phenotype must include characteristics that can be made visible by some technical procedure. Another extension adds behaviour to the phenotype since behaviours are also affected by both genotypic and environmental factors.
Biston betularia morpha
typica, the standard light-coloured Peppered Moth.
Biston betularia morpha
carbonaria, the melanic Peppered Moth, illustrating discontinuous variation.
Second, the phenotype is not simply a product of the genotype, but is influenced by the environment to a greater or lesser extent (see also
phenotypic plasticity). And, further, if the genotype is defined narrowly, then it must be remembered that not all heredity is carried by the
nucleus. For example,
mitochondria transmit their own
DNA directly, not via the nucleus, though they divide in unison with the nucleus.