Anatomy & Physiology I and II

Anatomy & Physiology Study Guide Proteins are formed from amino acids and contain carbon, hydrogen, oxygen, and nitrogen: • Proteins are chains of amino acids. Each amino acid consists of an amino group, a carboxylic acid group, a hydrogen atom, and an R group (side chain) attached to a central carbon atom. A polypeptide is a linear sequence of amino acids held together by peptide bonds; proteins are polypeptides containing over 100 amino acids. • The four levels of protein structure are primary structure (amino acid sequence), secondary structure (amino acid interactions, such as hydrogen bonds), tertiary structure (complex folding, disulfide bonds, and interaction with water molecules), and quaternary structure (formation of protein complexes from individual subunits). • The reactants in an enzymatic reaction, called substrates, interact to yield a product by binding to the enzyme’s active site. Cofactors are ions or molecules that must bind to the enzyme before substrate binding can occur. • The shape of a protein determines its functional characteristics. DNA and RNA are nucleic acids: • Nucleic acids store and process information at the molecular level. The two kinds of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). • 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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