John McMurry, Professor Emeritus

Figure 28.1 If these Afghan hounds look similar, that’s because they’re identical—all cloned from somatic cells of the same donor. (credit: modification of work “Figure 1” in “Birth of clones of the world’s first cloned dog” by Kim, M.J., Oh, H.J., Kim, G.A. et al./Sci Rep 7, 15235 (2017), CC BY 4.0)

Chapter Contents

28.1 Nucleotides and Nucleic Acids

28.2 Base Pairing in DNA

28.3 Replication of DNA

28.4 Transcription of DNA

28.5 Translation of RNA: Protein Biosynthesis

28.6 DNA Sequencing

28.7 DNA Synthesis

28.8 The Polymerase Chain Reaction

28 • Why This Chapter?

Nucleic acids are the last of the four major classes of biomolecules we’ll consider. So much has been written and spoken about DNA in the media that the basics of DNA replication and transcription are probably known to you. Thus, we’ll move fairly quickly through the fundamentals and then look more closely at the chemical details of DNA sequencing, synthesis, and metabolism. This field is moving rapidly, and there’s a lot you may not be familiar with.

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are the chemical carriers of a cell’s genetic information. Coded in a cell’s DNA is the information that determines the nature of the cell, controls its growth and division, and directs biosynthesis of the enzymes and other proteins required for cellular functions.

In addition to nucleic acids themselves, nucleic acid derivatives such as ATP are involved as phosphorylating agents in many biochemical pathways, and several important coenzymes, including NAD⁺, FAD, and coenzyme A, have nucleic acid components. See Table 26.3 for their structures.