3.  (5 points) High levels of glucose in the blood cause tissue damage, while high blood fructose levels do not. Explain this using the structures and chemical reactivities of the two hexoses.

4.  (15 points) The following enzyme mechanisms were presented in class:

Ribonuclease A

Thermolysin

Triosephosphate Isomerase

Lysozyme

5.  Choose one and show the reaction that is catalyzed. Then show a detailed description of the enzyme mechanism. Be sure to emphasize the type(s) of catalytic methods that are used, e.g.: general acid/base, metal ion, induced fit, etc.

6.  (5 points) Why are polar membrane lipids in a constant cycle of synthesis and breakdown?

7.  (10 points) Why does a build up of breakdown products cause problems? Why can’t these products just be recycled? Where does synthesis occur? Where does breakdown occur. What are the starting materials for membrane lipid synthesis?

8.  (10 points) The following enzyme deficiencies were discussed in class. Choose two and describe the symptoms, genetic characteristics (eg: autosomal recessive, X-linked dominant, etc.) and rates of occurrence for the following diseases:

Tay Sach’s

Niemann-Pick

Gauchers’s

Sandoff’s

Gaucher’s disease

Fabry’s disease

Sandoff’s disease

Generalized gangliosidosis

9.  (5 points) For the two diseases that you chose above, relate the symptoms of each disease to the enzyme defect.

10.  (16 points) Complete the following table:

11.  (10 points) Triose phosphate isomerase catalyzes an important glycolytic reaction. The mechanism involves a proton transfer from a neutral histidine. (The pKa for the proton on the nitrogen in neutral histidine is 18.8! ) There must be some environmental effects that alter this pKa so that this proton dissociates during the enzyme mechanism. Describe a possible environment for this histidine inside triose phosphate isomerase.