4.3 Genotype to Phenotype

Figure 4.3 The four bases to a DNA strand

Simply, an individual’s cells read genetic information in our DNA like words in a book, although DNA’s “alphabet” is a mere four letters—Adenine (expressed as “A”), Guanine (G), Cytosine (C), and Thymine (T). These letters combine to form an individual’s unique genotype, its total set of genes—but organisms are more than just a sequence of letters. In fact, identical twins, with almost the exact same genotype, may look and act very different from each other. An individual’s phenotype is its observable characteristics, and the result of a lifetime of environmental influences acting on his or her genotype. For example, prolonged exposure to the sun makes some people tan, while others burn; how you react to the sun is a result of your genotype. Yet nobody is born tanned or sunburned. Rather, ultraviolet radiation from the sun activates your genes to produce pigments that will darken skin.

 

An icon of a chromosome labeled genes + an icon showing sunlight and water labeled environment creates an icon showing corn plants labeled phenotype.
Figure 4.4 An individual’s phenotype is created by the combination of its genotype and environmental conditions. From Berkeley Evolution.

 

  Check Yourself

Content on this page was originally published in The Evolution and Biology of Sex by Sehoya Cotner & Deena Wassenberg and has been expanded and updated by Katherine Furniss & Sarah Hammarlund in compliance with the original CC-BY-NC 4.0 license.

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Introduction to the Evolution & Biology of Sex Copyright © by Katherine Furniss and Sarah Hammarlund is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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