The enzyme inorganic pyrophosphatase contributes to making many biosynthetic reactions that generate inorganic pyrophosphate essentially irreversible in cells. By keeping the concentration of PP$_i$ very low, the enzyme "pulls" these reactions in the direction of PP$_i$ formation. The synthesis of ADP-glucose in chloroplasts is one reaction that is pulled in the forward direction by this mechanism. However, the synthesis of UDP-glucose in the plant cytosol, which produces PP$_i$, is readily reversible in vivo. How do you reconcile these two facts?

Given some ${ }^{14} \mathrm{CO}_2$ and all the tools typically present in a biochemistry research lab, how would you design a simple experiment to determine whether a plant was a typical $\mathrm{C}_4$ plant or a CAM plant?

If a maize (corn) plant is illuminated in the presence of ${ }^{14} \mathrm{CO}_2$, after about 1 second, more than $90 \%$ of all the radioactivity incorporated in the leaves is found at C-4 of malate, aspartate, and oxaloacetate. Only after 60 seconds does ${ }^{14} \mathrm{C}$ appear at $\mathrm{C}-1$ of 3-phosphoglycerate. Explain.

Segregation of Metabolism in Organelles

What are the advantages to the plant cell of having different organelles to carry out different reaction sequences that share intermediates?

Where does fatty acid synthesis occur in the cell?

Predict the major products of the following reactions, including stereochemistry. (a) cyclohexene+$\mathrm{KMnO}_{4} / \mathrm{H}_{2} \mathrm{O}$ (cold, dilute). (b) cyclohexene+peroxyacetic acid in water. (c) cis-pent-2-ene+$\mathrm{OsO}_{4} / \mathrm{H}_{2} \mathrm{O}_{2}$. (d) cis-pent-2-ene+peroxyacetic acid in water. (e) trans-pent-2-ene+$\mathrm{O} \mathrm{s} \mathrm{O}_{4} / \mathrm{H}_{2} \mathrm{O}_{2}$. (f) trans-pent-2-ene+peroxyacetic acid in water

Determine the area under the standard normal curve that lies to the left of

(a) $z=-3.49$

(b) $z=-1.99$

(c) $z=0.92$

(d) $z=2.90$

Synthesis of L-Malate in Wine Making The tartness of some wines is due to high concentrations of L-malate. Write a sequence of reactions showing how yeast cells synthesize L-malate from glucose under anaerobic conditions in the presence of dissolved $\mathrm{CO}_2\left(\mathrm{HCO}_3{ }^{-}\right)$. Note that the overall reaction for this fermentation cannot involve the consumption of nicotinamide coenzymes or citric acid cycle intermediates.

Glycogen storage diseases are the result of a defective enzyme involved in pathways for glycogen storage or degradation. What is the effect of a defective glycogen synthase enzyme

Ethanol Affects Blood Glucose Levels The consumption of alcohol (ethanol), especially after periods of strenuous activity or after not eating for several hours, results in a deficiency of glucose in the blood, a condition known as hypoglycemia. The first step in the metabolism of ethanol by the liver is oxidation to acetaldehyde, catalyzed by liver alcohol dehydrogenase:

$$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH}+\mathrm{NAD}^{+} \rightarrow \mathrm{CH}_3 \mathrm{CHO}+\mathrm{NADH}+\mathrm{H}^{+}$$

Explain how this reaction inhibits the transformation of lactate to pyruvate. Why does this lead to hypoglycemia?

Write the Ka expression for each of the following in water:

HCN,

Inorganic Pyrophosphatase The enzyme inorganic pyrophosphatase contributes to making many biosynthetic reactions that generate inorganic pyrophosphate essentially irreversible in cells. By keeping the concentration of $P P_i$ very low, the enzyme "pulls" these reactions in the direction of $\mathrm{PP}_{\mathrm{i}}$ formation. The synthesis of ADP-glucose in chloroplasts is one such reaction. However, the synthesis of UDP-glucose in the plant cytosol, which also produces $\mathrm{PP}_{\mathrm{i}}$, is readily reversible in vivo. How do you reconcile these two facts?

Show that the resistance required to achieve a heart rate H, in beats per minute, is given by the equation R = ((-60/(HC ln (1 - (Vmax/Vs))). where C is the capacitance, Vs. is the source voltage, and Vmax is the capacitor voltage at which discharge occurs.

Sketch the shape of an s orbital and a p orbital.