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Understanding the difference between genotypes and phenotypes seems unimportant to many people, but understanding this is essential to understanding the theory of evolution through natural selection. Danish botanist Wilhelm Johannsen was the first to coin the terms phenotype and genotype and, in 1911, he published them on paper.
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What is a Genotype?
The actual set of genes an organism has, or is made up of, is a genotype. The genetic material is made up of DNA, for sexually reproducing organisms, which are given by the sperm and egg of the parents. The transfer of genes from the parents to the child is controlled by precise molecular mechanisms. Organisms with different genotypes can possess genes that are different in just a single locus.
An asexually reproducing organisms' DNA and genetic material is an exact copy of the organism's parent, due to no fusion of the sperm and egg.
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What is a Phenotype?
An individual's anatomical features or observed traits, such as physiology, structure, and behavior, are phenotypes. The behavioral and physical characteristics, such as shape, metabolic activities, size, and color, fall under an organism's phenotype. These behavioral characteristics and physical attributes are what determines an organism's ability to reproduce and survive in the environment. To a large extent, an organism's phenotype is determined by its genotype.
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The Difference Between Genotypes and Phenotypes
The difference between genotypes and phenotypes is something that must be understood to fully understand an organism. Because a phenotype is determined mostly by a genotype, phenotypes are dependent on their inherited genes. However, genes are only part of the equation. Three factors determine an organism's phenotype: the genetic makeup an organism got from its parents, development noise, and the environment. Hair is a good example. An individual's genes determines whether or not they have hair on their head, but how long this hair remains depends on environmental factors, such as excess sunlight, chemicals used on the head, or poor diet. This shows that phenotype is influenced by the environment.
Several organisms may have different phenotypes, but have a similar genetic makeup. Identical twins are a good example. They have the same genetic makeup and they look alike, but they possess different phenotypes. How is this possible? Identical twins have differences that allow those who are close to them to tell them a part. Also, their fingerprints are different. Thus, individuals or organisms can have different phenotypes, but the same genotype. For some this seems like a phenomenon, but science has proved there is no phenomenon behind it.
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University of Washington. (2010). Genotypes and Phenotypes. Retrieved on May 31, 2010 from the University of Washington: http://www.stat.washington.edu/thompson/Genetics/1.3_genotypes.html
Blamire, J. (2000). Genotype and Phenotype. Retrieved on May 31, 2010 from Brooklyn College: http://www.brooklyn.cuny.edu/bc/ahp/BioInfo/SD.Geno.HP.html