Chapter 28

A molecule in which the energy of metabolism is stored is (a) glucose; (b) DNA; (c) RNA; (d) glycerol; (e) ATP.

Of the following, the one that is not a constituent of a nucleic acid chain is (a) purine base; (b) phosphate group; (c) glycerol; (d) pentose sugar; (e) pyrimidine base.

The structure of the DNA molecule is best described as (a) a random coil; (b) a double helix; (c) a pleated sheet; (d) partly coiled; (e) a branched chain.

The \(R\) group \(-\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\) is that of what amino acid? (a) alanine; (b) serine; (c) threonine; (d) arginine; (e) none of these.

Which molecule is not optically active? (a) 1,2 -dichlorobutane; (b) 1,4 -dichlorobutane; (c) 1,3 -dichlorobutane; (d) 1,2 -dichloropropane; (e) none of these.

Which of the following amino acids does not have a chiral carbon? (a) glycine; (b) alanine; (c) threonine; (d) lysine; (e) none of these.

Enantiomers always (a) have an asymmetric carbon; (b) have different physical properties; (c) change the color of light; (d) rotate polarized light; (e) none of these.

The \(R\) group of valine is (a) \(-\mathrm{CH}_{2} \mathrm{OH}\) (b) \(-\mathrm{CH}_{2} \mathrm{COOH} ;(\mathrm{c})-\mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}\) (d) \(-\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\); (e) none of these.

Amino acids are joined into proteins by (a) \(3^{\prime}-5^{\prime}\) linkage; (b) a glycosidic bond; (c) \(\beta(1 \longrightarrow 4)\) linkage; (d) a condensation reaction; (e) none of these.

Which of the following fatty acids is unsaturated? (a) palmitic acid; (b) oleic acid; (c) lauric acid; (d) stearic acid; (e) none of these.

Upon complete hydrolysis of a pentapeptide, the following amino acids are obtained: valine, phenylalanine, glycine, cysteine, and tyrosine. Partial hydrolysis yields the following fragments: Val-Phe; Cys-Gly; Cys-Val-Phe; Tyr- Phe. If glycine is the N-terminal acid, what is the sequence of amino acids in the polypeptide?