91Ó°ÊÓ

DNA has been called the "thread of life." Comment on the appropriateness of this expression.

Coupling ATP hydrolysis to a thermodynamically unfavorable reaction can shift the equilibrium of a reaction (see Chapter 19). (a) Calculate \(K\) for the hypothetical reaction \(A \longrightarrow B\) when \(\Delta G^{\circ}\) is \(23 \mathrm{kJ} \mathrm{mol}^{-1}\) at \(25^{\circ} \mathrm{C}\) (b) Calculate \(K\) for the same reaction when it is coupled to the hydrolysis of \(\operatorname{ATP}\left(\Delta G^{\circ \prime}=-30 \mathrm{kJ} \mathrm{mol}^{-1}\right)\) Compare with the value obtained in part (a). (c) Many cells maintain [ATP] to [ADP] ratios of 400 or more. Calculate the ratio of \([\mathrm{B}]\) to \([\mathrm{A}]\) when \(\left.[\mathrm{ATP}] /[\mathrm{ADP}]=400 \text { and } \mathrm{P}_{\mathrm{i}}\right]=5 \mathrm{mM} .\) Compare this ratio to that for the uncoupled reaction.

The coagulation of egg whites by boiling is an example of (a) saponification; (b) inversion of a sugar; (c) hydrolysis of a protein; (d) denaturation of a protein; (e) condensation of amino acids.

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

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.

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.

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