I. (Z)-9-Tricosene is a pheromone on the surface of female Musca domestica the common housefly. Outline its probable biosynthesis from acetic acid units.

2. Outline the biosynthetic route to 5-methyltricosane.

3. Suggest a probable biosynthetic route to (9£,11^-9,11-tetra-decadienyl acetate, the sex pheromone of the apple moth Epiphytas postvittana, from palmitic acid.

4. [18,18,18-2H3]Stearic acid was used in the study of the formation of 9-hydroxy- and 10-hydroxy-dec-2-enoic acids (see Figure 3.32) in queen and worker honeybees, using mass spectrometry. How many of the deuterium atoms per molecule would you expect to find in 9-hydroxydec-2-enoic acid, and how many in 10-hydroxydec-2-enoic acid?

5. When 2-fluorostearic acid was used in the study in Question 4, none of the 9-hydroxy- or 10-hydroxy-decenoic acids was formed. Why was that?

6. If all the hydrogen atoms on carbon in isoleucine were replaced by deuterium, show where and how many deuterium atoms would be present in 14-methylhexadecanoic acid (Figure 3.12) if it is made from the labelled isoleucine.

7. Bruchin A is a substance made by certain strains of the larvae of the pea weevil Bruchus pisorum. It causes the formation of callus tissue around the larva inside the pea. Its structure is specific; propionic, lactic or 3-hydroxybutyric acids or no acid esterified onto the long chain diol all give inactive compounds. Predict the biosynthetic origin of bruchin A.

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