1.  Describe how you would measure glycogen phosphorylase activity?  Draw a graph that shows glycogen phosphorylase activity before and after phosphorylation of this enzyme.  Also show on the graph how activity will change upon glycogen depletion.
 
 
 

2.  How would you make 250 milliliters of 1.4M NaCl?  What percent solution is this?  Hint: the molecular weight of NaCl is 58.5.
 
 
 

Answer 5 of the following 7 questions

3.  Glycogen and cellulose are both polymers of glucose.  Most animals, however, cannot  utilize cellulose as an energy source.  Why?
 
 
 

4.  Typically, the following concentrations of ions are found inside and outside mammalian cells:

Inside:       Na+ = 15mM          K+ = 150mM          Cl- = 10mM
Outside:     Na+ = 150mM        K+ = 5mM              Cl- = 120mM

Gamma-aminobutyric acid (GABA) is a neurotransmitter that, upon binding to its receptor, results in the opening of ligand-gated Cl- channels.  What effects would GABA have on a muscle cell?
 
 
 

5.  Recently, an experimental drug, LY354740, has been shown to alleviate some of the signs of schizophrenia in rats.  Also recently, an FDA advisory committee recommended approval of Herceptin as a breast cancer therapy.  Compare and contrast the modes of action of these two compounds.
 
 
 

6.  The binding of a sperm to an egg and the binding of epinephrine to its receptor on a myocardial cell both result in increased intracellular Ca2+ levels.  Compare and contrast these two systems.
 
 

7.  You discover a new hormone, Wildcatine, and hypothesize that it binds to a receptor on pancreatic cells, thereby triggering a signal transduction pathway utilizing Ca2+ as a second messenger.  How would you test this hypothesis?
 
 

8.  A recent report showed that the hormone estrogen can bind to two different receptors, ERa and ERb.  Furthermore, the researchers demonstrated that binding of estrogen to ERa results in increased production of certain proteins, but binding of estrogen to ERb results in decreased production of these proteins.  How can estrogen bind to two different receptors and cause such different outcomes?
 
 

9.  Clostridium botulinum, the bacteria that causes botulism, produces a neurotoxin that inhibits the release of acetylcholine from pre-synaptic cells at neuromuscular junctions.  Clostridium tetani, the bacteria that causes tetanus, produces a neurotoxin that causes the increased activity of acetylcholine at neuromuscular junctions.  What effects would these two neurotoxins have on a muscle cell and why?