Zoology 211; Fall, 1995

W. Higgins, Round II
 

DIRECTIONS:
 

1.Draw the complete structure (i.e., all the carbons) of phosphatidylcholine with mono-unsaturated, 12 carbon atom long side chains, and using a "C" to represent choline.
 

 
 
 

2.Phospholipids spontaneously form bilayers or liposomes when mixed in an aqueous solution.Why is ?G negative for this reaction?
 

 
 
 

3. As the aquatic plants in my grandmother's fish pond prepare enter the spring and summer, they do three things to their membrane lipids.  List them below:
 

 1._____________________________________________________________  

 2._____________________________________________________________  

 3._____________________________________________________________
 
 

4. List three ways that integral proteins may be attached to a membrane.  Do not consider transmembrane proteins:

 1.  _____________________________________________________________

 2.  _____________________________________________________________

 3.  _____________________________________________________________
 

5. List four DIFFERENT and unrelated characteristics of a uniport transport system:

1.  _____________________________________________________________

2.  _____________________________________________________________

3.  _____________________________________________________________

4.  _____________________________________________________________

6. List, describe or draw the sites on Na⁺ - K⁺ ATPase that bind the ions and ATP.  Be sure to indicate on which side of the membrane they occur before ATP is hydrolyzed:
 
 
 
 
 
 

 *Dr. Harley Schmedlap, Jr., noted physiologist, 211 alumnus, and part-time pizza delivery driver, recently struck and killed an unfortunate and heretofore unknown little creature while cruising on Campus Drive.  Never one to miss the opportunity to study a new animal or to pass up an extra pizza topping, the good doctor named it Roadkillus higginsii and began a study of its cellular physiology.  This animal has some rather strange cellular components.   Dr. Schmedlap requires your help to answer questions 6, 7, and 8 below:
 

7. Schmedlap was able to study the entry of glucose into the animal's red blood cells.  He also noted that the animal's extracellular fluids contained 100 mM Na⁺.  Examine his data and provide the answers to the questions below:

Blood Glucose uptake fromGlucose uptake from blood

[GLUCOSE] (mM)        blood (umoles/min/10⁶cells)        with no Na⁺

 2                                    1                                                    0.01

 4                                    2                                                    0.03

 6                                    3                                                    0.04

 8                                    4                                                    0.06

10                                   5                                                    0.07

12                                   5                                                    0.09
 
 
 

a. What type of glucose transport mechanism is at work here?  How did you arrive at this conclusion from the data?  (Be complete and specific!)
 
 
 
 
 
 
 

b. In 25 words or less, tell Schmedlap what other experiment he could run with these red blood cells to confirm this opinion:
 
 
 
 
 
 

c. Under normal conditions, what is the affinity constant for the system? __________________
 

d. Under normal conditions, what is the V_max for the system? _________________________

e. With no extracellular Na⁺, how does glucose most likely enter?

________________________________________
 
 

8. These red blood cells have an internal osmotic pressure of 250 mOsm consisting of the usual intracellular solutes.  Please describe the osmicity and tonicity of the following solutions and tell Schmedlap what happens to the cell volume when they are placed in each of them:
 
 

9. Schmedlap found the following strange ion concentrations in this little beast's nerve cells:
 

a. Write the equation for accurately determining the membrane potential:
 
 

b. Solve it and give the correct units and sign:_____________________________
 

c. The equilibrium potential for GL₄⁼ is _________________________________
 

d. At each of the membrane potentials (V_m) listed below, determine which way Z⁺ would move:
 

 If V_m = -59 mV, then Z⁺ will _______________________
 

 If V_m = +59 mV, then Z⁺ will _______________________
 

 If V_m = -70 mV, then Z⁺ will _______________________
 

e. If the equilibrium potential for Q⁺⁺ = -118 mV, what is the [Q⁺⁺]_in? 

______________________
 

f. If [Z⁺]_out increases, Vm _____________________________________
 

g. List three changes in membrane permeability that could produce an ipsp: 

1.________________2.________________3.________________
 

10. Draw the membrane components (and the subunits of all components) of a target cell that responds to a signal molecule by producing cyclic AMP.
 

11. On the graph, plot the data expected for:

X which enters by simple diffusion
 

Y which enters by uniport
 

Z which enters by symport
 
 

Label each plot, please!!!!!
 
 

12.  Just for grins and a few easy points each, answer each of the following with (I)ncrease, (D)ecrease, or (N)o (C)hange (NC):  

a. As the area of plasma membrane surface increases, the rate of entry of a lipid soluble solute into a cell  

b. As the number of uniport carriers on a cell membrane increases, the transport V_max  

c. As V_m becomes depolarized, nerve cell membrane sodium conductance (permeability)

d. As the affinity of a receptor for a signal molecule increases, the K_D of the receptor
 

e. After stimulus intensity increases, the number of postsynaptic receptors occupied by neurotransmitter
 

f. As the frequency of action potentials on a nerve decreases, the synaptic concentration of neurotransmitter
 

g. As stimulus intensity increases, the amplitude of a resulting action potential
 

h. As stimulus intensity increases, the amplitude of a resulting graded potential
 

i. As external calcium concentration decreases, the amount of neurotransmitter released per action potential
 

j. As polar groups are added to a small lipid-soluble molecule, its rate of entry into a cell by diffusion

                                                a__________
 

                                                b__________
 

                                                c__________
 

                                                d__________
 

                                                e__________
 

                                                f__________
 

                                                g__________
 

                                                h__________
 

                                                i__________
 

                                                j__________