Anatomy & Physiology

Anatomy & Physiology Study Guide • Nucleic acids are chains of nucleotides. Each nucleotide contains a sugar, a phosphate group, and a nitrogenous base. The sugar is ribose in RNA and deoxyribose in DNA. • DNA is a two-stranded double helix containing the nitrogenous bases adenine, guanine, cytosine, and thymine. RNA consists of a single strand; it contains uracil instead of thymine. ATP is a high-energy compound used by cells: • Cells store energy in the high-energy bonds of high-energy compounds. The most important high-energy compound is ATP (adenosine triphosphate). Cells make ATP by adding a phosphate group to ADP (adenosine diphosphate). When ATP is broken down to ADP and phosphate, energy is released. The cell can use this energy to power essential activities.

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