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Name: Leonard D.
Status: Educator
Age: 40s
Location: N/A
Country: N/A
Date: 2001

Does the amino acid Tyrosine play any role in how hair color adheres to the hair shaft?

Helen Kreutzer and Adrianne Massey have come out with a new edition of their book "Recombinant DNA and Biotechnology" . In this book they include an activity that deals with the pigmentation of Labrador retrievers. On page 366 of the teacher's edition: "Pigmentation in dogs and other mammals (including you) is caused by the relative amounts and types of two classes of pigment: eumelanin and phaeomelanin. The eumelanins are black and brown pigments and phaeomelanins are red and yellow. Both.. are synthesized in pigment-producing cells called melanocytes......First the enzyme tyrosinase converts the amino acid tyrosine to dopaquinone. If tyrosinase-related protein 2 is present, it converts the dopaquinone to a version of eumelanin that has a brown color. If the enzyme tyrosinase related protein 1 is present, it converts the brown version of eumelanin into the final black pigment. If there is no TRP-1, the color remains brown.

There is more to this activity that shows students why yellow color is produced and why albinos result as well.


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