Total points: 23

General
•	Some Figures are provided. You may use your (one) page of notes. Otherwise, “closed book”: no models, books, other notes, or periodic table.
•	If a question isn’t clear, please ask me about it.
•	In a multi-part question, if a difficulty with one part is keeping you from continuing, please see me.
•	Some questions request a simple answer and an explanation. It’s the explanation that is important. No credit for answer without a requested explanation. 
•	When you are asked to mark something, please do so clearly, and label it clearly.

1. (2 pts.) A buffer used in biochemistry labs is bicine. Bicine is N,N-bis(2-hydroxyethyl)glycine. (Bis is an alternative to di; bis is commonly used with complex groups.) Draw the structure of bicine.

2. (2 pts.) Fish that live at temperatures below 0 C (such as in the Antarctic) have “anti-freeze proteins” to help prevent water from freezing in their systems. One type of anti-freeze proteins contains mainly the amino acids alanine and threonine. A sugar is attached to the side chain of one of these amino acids. 

The following parts refer to this anti-freeze protein, and make use of common X402 level chemistry. The parts are closely related.

a. (1/2 pt.) Which amino acid is the sugar attached to? 

b. (1 1/2 pts.) How? That is, what functional group of the sugar connects to what functional group of the amino acid side chain? What functional group is formed? (The linkage is stable.)

3. (2 pts.) Most types of biological molecules are soluble in water (although there is a wide variation). What type (class) of biochemical is typically insoluble in water. What feature of the chemical structure makes them insoluble? What role do these insoluble chemicals play in biology? Why is the insolubility important in that role?

4. (8 pts.; 1 pt. per part except as noted) Continues on next page. The following structure shows a synthetic lipid that was reported recently. It was used in nanotechnology studies, assembling lipid layers on carbon nanotubes.

Many of the parts below are substantially independent, though some are related. (That is, if you are stuck on one part, go on and do other parts. You may be able to do them fine, and you may get a hint about an earlier part from going on.)

You can answer many of these by marking the structure above. Please be sure your markings are well-labeled.

a. Why is this considered a lipid? Point out specific features of the molecule that make it a lipid. (Don’t worry that it is not a bio-molecule. The idea of synthetic lipids is well accepted.)

b. In the common bio-lipids, groups are linked to the glycerol by ester linkages. 

–	How are the three groups linked to the glycerol in this lipid? 
	
–	Are all three groups linked the same way (same functional group)? If not, explain.

c. How is the arrangement of the three groups on the glycerol different here than in common membrane lipids? (Note that this question does not refer to the specific type of chemical linkage, or functional group; that is in the previous part.)

d. For each of the two nitrogen atoms in the structure: what functional group is it? Include the “degree” (primary etc).

e. (2 pts.; 1 pt. per N) For each nitrogen atom, along with its directly bonded hydrogens, in the structure: can it serve as a hydrogen bond donor? as a hydrogen-bond acceptor? Briefly explain any “no” answers.

f. This chemical could be hydrolyzed, at one position. Mark the bond that would be hydrolyzed (in a common hydrolysis reaction). What are the products of the hydrolysis? (You need not draw the entire structures; just show the key groups that change.)

g. Mark and label all the major acidic and basic groups.

5. (4 pts.; 1 pt. per part) In each part below, give one compound from the citric acid cycle that has the indicated feature. Draw the compound and point out the feature. If there is no such compound in the cycle, say so.

a. a ketone					b. a secondary alcohol

c. an ether					d. chiral; mark the stereocenter(s)

6. (1 pt.) As you may know, detergents are put in gasoline. Sketch a micelle (lipid droplet) as it would occur in gasoline. (You can think of one of the fatty acids as the lipid molecule, but it is fine to just sketch the lipid diagrammatically, with a head and tail, so long as you label the key relevant properties.)

7. (2 pts.) The structure below is for the drug AG7088. It has been shown to inhibit certain cold viruses, and is considered a candidate worth further study as an inhibitor of SARS virus.

AG7088 is an inhibitor of the viral protease; not surprisingly, it is a pseudopeptide. It can be thought of as a peptide containing three subunits linked by peptide bonds. (Ignore “P2”, which is not identified here. Also, this molecule contains an N-O bond, which is unfamiliar to you; nothing below deals with this.)

a. (1 pt.) Mark the two peptide bonds in the main chain. For each, mark the specific bond that is created during amide formation.

b. (1/2 pt.) What is the most hydrophobic part of the side chains in AG7088?

c. (1/2 pt.) What is the charge on this drug (at pH 7)? Explain.

8. (2 pts.; 1 pt. per part) One major purpose of metabolizing your food is to produce energy. ATP is the common energy carrier in cells. In each part below, give one reaction from the citric acid cycle that has the indicated feature, regarding ATP production. You can refer to the reactions by number, from the Fig. If there is no such reaction in the cycle, say so.

a. Results in the direct production of ATP. 

b. Results in the production of 2 or 3 ATP, indirectly. Briefly explain how you can tell.

cq\bq4
8/24/03