Chapter 1: Heritable Material

What defines you as a human being? Why is every human different, even “identical” twins? Your body contains 10 to 50 trillion cells. Each cell contains instructions for the processes and functions of a human body. The information to carry out these functions is encoded in your deoxyribonucleic acid (DNA), half of which you inherited from each of your parents. What evidence supports the claim that DNA is the heritable material? How does DNA relay its information to the next generation? For many years, scientists mistakenly thought that protein was the heritable material. However, over many years of clever and now famous experiments, the evidence mounted in favor of DNA and against protein as the carrier of genetic information. One of the most famous discoveries in science was the double helix structure of DNA. DNA’s structure helps explain how your DNA replicates itself to produce the next generation. Chemical modifications to DNA can lead to differences among individuals, including some we can observe and some that make us sick. In Chapter 1, you will explore and interpret the original data from experiments that led to our current understanding of DNA as heritable information. Genetic information defines you as a human being and differentiates you as an individual. The five sections of Chapter 1 focus on information at the molecular level.

Dog breeds vary in phenotype, but they are all the same species. A is courtesy Kevin G. Smith, Davidson, NC. B - D are courtesy Abbye W. Stooksbury, Marietta, GA. 

    Contents

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    Learning Objectives