Fig. 3-6, p. 38

Fig. 3-5, p. 37

one of the estrogens Fig. 3-4, p. 37 testosterone

glucosefructose sucrose Fig. 3-6, p. 38 c Formation of a sucrose molecule

Fig. 3-8, p. 39

c Glycogen. In animals, this polysaccharide is a storage form for excess glucose. It is especially abundant in the liver and muscles of highly active animals, including fishes and people. Structure of cellulose

glycerol three fatty acid tails Triglyceride, a neutral fat Fig. 3-11, p. 40

Fig. 3-12, p. 41

hydrophilic head two hydrophilic tails Fig. 3-13, p. 41

c Cell membrane section

Fig. 3-15, p. 42 carboxyl group amino group

Fig. 3-17, p. 43 a Protein primary structure: Amino acids bonded in a polypeptide chain.

Fig. 3-17, p. 43 b Protein secondary structure: A coiled (helical) or sheetlike array, held in place by hydrogen bonds ( dotted lines) between different parts of the polypeptide chain. helical coilsheet

Fig. 3-17, p. 43 c Protein tertiary structure: A chain’s coiled parts, sheetlike arrays, or both have folded and twisted into stable, functional domains, including clusters, pockets, and barrels. barrel

Fig. 3-17, p. 43 d Protein quaternary structure: Many weak interactions hold two or more polypeptide chains together as a single molecule.

alpha globin beta globin Fig. 3-18, p. 44 alpha globin b Hemoglobin is one of the proteins with quaternary structure. It consists of four globin molecules held together by hydrogen bonds. To help you distinguish among them, the two alpha globin chains are shown here in green, and the two beta globins are in brown.

Fig. 3-19, p. 45 VALINEHISTIDINELEUCINEGLUTAMATEVALINETHREONINEPROLINE sickle cell normal cell b One amino acid substitution results in the abnormal beta chain in HbS molecules. Instead of glutamate, valine was added at the sixth position of the polypeptide chain. c Glutamate has an overall negative charge; valine has no net charge. At low oxygen levels, this difference gives rise to a water-repellent, sticky patch on HbS molecules. They stick together because of that patch, forming rodshaped clumps that distort normally rounded red blood cells into sickle shapes. (A sickle is a farm tool that has a crescent-shaped blade.)

Fig. 3-20, p. 46 three phosphate groups base (blue) sugar (orange)

Fig. 3-21, p. 46

Fig. 3-22, p. 47 covalent bonding in carbon backbone hydrogen bonding between bases