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Willietta Gibson
Associate Professor of Biology
Department of Biological and Chemical Sciences
Bennett College
The Biochemistry of Curly and Straight Hair 

This interrupted case study examines basic concepts of chemical bonding by telling the story of “Madison,” who is learning about the texture of her hair and how it can transition between its natural curly state to a smooth, straight texture. The case can be used to teach or review the major categories of bonds (ionic, covalent and hydrogen), major macromolecules of life, and hydrolytic and dehydration reactions. It also explores how chemical relaxers and heat through blow drying and flat-ironing can change the nature of straight, wavy and curly hair through the disruption of protein shape. Students learn what it means when a protein has become denatured and how various variables such as pH, heat and salts can lead to the unraveling of the three-dimensional shape of proteins. This case is suitable for an AP high school course, or for an introductory biology or chemistry course for majors or non-majors; it can also be used as a review of basic biology and chemistry for students in an upper-level biochemistry course.