4. In what ways has Watson and Crick’s model of the double helix shaped the course of biological studies over the past 50 years? Watson and Crick first proposed the double helix as the three-dimensional structure of DNA. This has become the symbol of molecular biology. They saw the functional significance of base pairing rules, and in turn determined how DNA replicates. Prior to duplication hydrogen bonds are broken, and the double helix unwinds and separates. Each chain then acts as a template for the formation onto itself of a new companion chain. Two chains result (composed of one old strand and one new strand), and the sequence of base pairs are duplicated exactly. Their research spurred the Human Genome Project in which the goal was to determine all the genes in the human genome. 5. By what mechanisms can cells regulate gene activity? How do prokaryotes differ from eukaryotes in this regard? Genes provide the instructions for making specific proteins through RNA.
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