Exam2 Name_______________________

1. In the catalysis of a reaction, an enzyme

a. increases the K_eq.

b. increases the rate and increases the activation energy of the reaction.

c. makes the ΔG more negative for the reaction.

d. decreases the K_eq.

e. increases the rate and decreases the activation energy of the reaction.

2. By doing site directed mutagenesis experiments, researchers are able to generate mutants of proteins that have specific changes in their primary amino acid sequence. The sequence of the active site of phosphoglycerate mutase was being investigated using this technique. Based upon what you know about the enzyme mechanism, which of the following mutants will have no activity?

a. I and III

b. II and IV

 

c. III only

d. I, II and III

e. none of the above mutants

Part II: Short answer. Please write complete sentences when text is required. Draw structures when appropriate.

12. (5 points) Briefly describe the fate of pyruvate in a yeast cell that is growing under anaerobic conditions. What is the end product? Why does the yeast cell make this toxic product?

 

 

 

 

 

 

 

 

 

 

13. (10 points) You have just started to work in a biochemistry lab, and you are given the following recipe to make ³²P labeled ATP for your boss to use in his BIG experiment. Trial after trial after trial, you can not produce any labeled ATP using this recipe. Obviously, a mistake has been made in writing out the ingredients. Explain why this recipe doesn=t work. What would you change, to make this work.

Part III, Short Essay: Your answer should be written in complete sentences that are in well organized paragraphs. If you don=t want a portion to be graded, just put a line through it and I will not read it. Questions will be graded on content (14 points), organization (4 points), grammar (2 points). I realize these are rough drafts and I will fully consider that when I grade these. Each question is worth 10 points.

14. Fully describe the control mechanisms (thermodynamic and kinetic) involved in glycolysis. Include a description of the glycolytic enzymes that are regulated, including how they are inhibited and stimulated. Are all of the reactions kinetically controlled? Why or why not?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15. An ER patient was experiencing cardiac arrest, so the attending physician barked, Aepi IV STAT@. The freaked out first year resident grabbed a vial that he thought was epinephrine and injected the contents into the patient. The patient recovered from the Aflat line@ and started to regain consciousness, only to quickly black out and go into a comatose state. The heart was beating just fine (blip, blip, blip). The nurse who was cashing out the crash cart then discovered the error of the first year resident, and immediately told the resident that the patient needed some insulin quickly. (No epi was used, and another drug was missing.) Upon receiving an injection of insulin, the patient began to recover consciousness. A blood analysis later confirmed that the patient=s blood glucose level was Athrough the roof@ and thus responsible for the comatose state of the patient. (Cashing out the crash court is when a nurse goes through and tallies up all of the drugs that were used for the cardiac arrest so the cart can be restocked and the patient can be billed.) Also, the drugs are placed alphabetically in the cart and a number of drugs are packaged very similarly.

b. What drug was erroneously given to the patient? How did it raise the patient=s blood glucose levels? Please answer this question in detail. (Use the back of this page if needed.)