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Name a phenotype trait and discuss how you think it is influenced by both genetics and...

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lcowan6 | Student, Undergraduate | (Level 1) Salutatorian

Posted February 16, 2013 at 1:55 PM via web

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Name a phenotype trait and discuss how you think it is influenced by both genetics and the environment.

“Nature vs. nurture” with regard to phenotype vs. genotype. This is a question of how a trait is influenced by both genetics and the environment. In this phrase, "nature" is the equivalent of genetics, and "nurture" is the equivalent of the environment.  For example, people could be genetically inclined to be tall (genetics/nature), but if they do not have adequate nutrition growing up, (environment/nurture) they may actually end up short. 

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gojsawyer | Teacher | (Level 1) Assistant Educator

Posted February 16, 2013 at 5:16 PM (Answer #1)

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This question actually addresses three areas: 1) the definition of a phenotype (or phenotypic) trait, 2)how the phenotypic trait is influenced by genetics, and 3) how the phenotypic trait is influenced by the environment. Further, a perspective on the difference between a genotype and a phenotype is relevant.


First, Enotes offers a helpful definition: “The term genotype describes the actual set (complement) of genes carried by an organism. In contrast, phenotype refers to the observable expression of characters and traits coded for by those genes.” As such, a phenotypic trait may be understood as an organism’s observable characteristics for which genes code.


Second, pick one observable phenotypic trait and describe that as a kind of case study. Try to keep this aspect fairly simple in terms of both the trait and the organism. For example, a phenotypic trait such as hair, skin, or eye color in a mammal such as a human is actually a bit complex. Such traits are coded by more than one gene and from genes from two parents. Further, for the example of height in the question, try to be as specific as possible by distinguishing between male and female height, and how and when that trait is expressed and/or influenced (e.g. bone growth, specific bones, growth hormones, puberty, etc.).


Third, try to work out a simple Punnett square for the phenotypic trait. In the question, for example, the trait for height-tall as a dominant trait may be expressed as TT or Tt, with tt expressing height-short.  A person “genetically inclined” to be tall may be TT or Tt.


Fourth, identify factors that might cause certain dominant genetic traits to be expressed phenotypically to appear recessive. In the question, for example, the TT genetic trait is expressed to appear as tt due to nutrition. Yet, it is not clear why and which aspect of nutrition at which point in the organism (or person’s) life causes the stunted growth and whether with subsequent adequate nutrition the person can reach full height.


Last, it may be helpful to review some real-world case studies of phenotypic vs. genotypic traits as influenced by genetics and the environment. The case of England’s peppered moth is a good example.


Enotes has some good references as starting points, which are included below. Best of luck with further study!

Sources:

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