Lecture.15.Fall.2013(1)

One gene one polypeptide not all proteins are enzymes

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Unformatted text preview: 2,3 citrulline arg1 arginine One Gene: One Enzyme • Thus: one gene seemed to affect only one protein (enzyme) • Genes seemed to regulate all biological processes. One Gene, One Polypeptide • Not all proteins are enzymes • Some proteins are composed of more than one polypeptide • One mutation can affect many phenotypes (pleiotropy) - how can a single mutant enzyme result in so many changes? Sickle Cell Anemia • Elongated red blood cells (erythrocytes) • Neel and Beet (1949): sickle cell is heritable Sickle Cell Anemia • Linus Pauling (1949): hemoglobin from patients with sickle cell anemia • migrates more slowly towards a positive charge • First evidence of a “molecular disease” Sickle Cell Anemia • Vernon Ingram (1957): ss hemoglobin differs in only one amino acid (Glu to Val) in the " chain • Glu is negatively charged; Val is neutral • Hemoglobin is a protein composed of four polypeptide chains (2 ! and 2 ") • Only the " chain was affected Conclusions...
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This document was uploaded on 02/25/2014.

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