Lab Section # _______________________         TA Name: ______________________

DIRECTIONS:
1. PRINT your name on each page of this examination NOW!!!!
2.  Place your answers only in the spaces provided.
3. When you are finished, you may turn in your exam and leave QUIETLY.
4. Keep your eyes on your own test.  Any attempt to ‘borrow’ answers from your neighbor will not be tolerated.
5. Sign the Honor Code statement below before turning in your examination.

SCOREBOARD:

QUESTIONS              POINTS            POINTS EARNED

1 - 15                              45                  _______________

16 - 19                            29                  _____________

20 & 21                          26                  _____________
 

                                            TOTAL  _______________

I certify that I neither sought nor gave any unauthorized information while taking this examination.

_____________________________________ ________________
 Signature                                                                   Date
__________________________________________________________________
 

Circle the one correct answer for each of the first 15 questions:

1. For catabolic reactions:
 a. G is positive
 b. S is decreasing
 c. H is negative
 d.  ATP must be used
 e.  involves protons

2. As summer approaches, the goldfish in my grandmother’s fish pond would:
 a.  decrease the number of glycerol groups in the membrane phospholipids
 b.  increase the number of double bonds in the membrane phospholipid fatty acids
 c.  decrease the number of methyl groups in the membrane phospholipid fatty acids
 d.  increase the degree of saturation in the membrane phospholipid fatty acids
 e.  decrease the length of the fatty acids in the membrane phospholipids

3. Which of the following would decrease the rate of diffusion of a solute molecule across a cell plasma membrane:
 a.  increased c
 b.  decreased x
 c.  increased surface area of membrane
 d.  decreased oil/water partition coefficient of solute molecule
 e.  increased extracellular [Na⁺]

4. If a solute molecule diffuses 0.01 mm in 1 sec, how long does it take this molecule to diffuse 1.0 mm?
 a.  10 sec
 b.  100 sec
 c.  1,000 sec
 d.  10,000 sec
 e.  100,000 sec

5. Enzymes
 a.  shift the equilibrium of a reaction to the right
 b.  change G
 c.  change H
 d.  change S
 e.  change the activation energy

6. Which of the following is NOT true of most transmembrane proteins:
 a.  contains  helices
 b.  contains primary structure
 c.  contains  pleated sheets
 d.  can only be extracted from the membrane by dissolving the membrane
 e.  are purple in the textbook

7. The famous 1925 Gorter and Grindel experiment:
 a.  demonstrated that the surface area occupied by the extracted lipids was equal to  one-half the surface area of the cells’ plasma membranes
 b.  demonstrated the relationship between surface area and rate of diffusion
 c.  provided evidence for a cell membrane with a lipid bilayer
 d  was observed in person by Dr. Higgins

8. A solute channel through a plasma membrane is most likely formed by
 a.  water
 b  phospholipids
 c.  fatty acid side chains
 d.  transmembrane proteins with  helices
 e.  glycogen

9. Phospholipids form a bilayer in water because they
 a.  are saturated
 b.  contain a sugar
 c.  are soluble in water
 d.  are amphipathic (both polar and non-polar)
 e.  are hydrophylic

10. A spontaneous reaction
 a.  requires a catalyst
 b.  is always endergonic
 c.  requires ATP
 d.  results in decreased entropy
 e.  has a negative G

11. Which of the following is NOT a characteristic of facilitated diffusion?
 a.  depends upon C
 b.  saturates or reaches a maximum velocity at high [solute]
 c.  depends upon the oil/water partition coefficient
 d.  is subject to competition
 e.  has a negative G

12.  In the active transport of glucose into most cells, the energy comes from
 a.  ADP
 b.  ATP
 c.  NADH
 d.  the Na⁺ concentration gradient across the plasma membrane
 e.  photosynthesis

13. Diffusion of a non-polar molecule across a cell membrane depends upon all of the following EXCEPT:
 a.  number of transport sites
 b. C
 c.  degree of solubility in oil or lipids
 d. x
 e.  Diffusion coefficient (D)

14. Which of the following statements are true for the membrane Na⁺ - K⁺ ATPase or pump?
 a.  it pumps 2 Na⁺  in and 3 K⁺ out
 b.  it pumps 3 Na⁺  in and 2 K⁺ out
 c.  it pumps 2 K⁺ in and 3 Na⁺ out
 d.  it pumps 3 K⁺ in and 2 Na⁺ out
 e.  is an example of symport

15. As the size of a cell increases, the volume of the cell is increasing at a rate proportional to:
 a.  the cube of the radius (i.e., r³)
 b.  the radius squared (i.e., r²)
 c.  the square of the distance between the cell walls (i.e., d²)
 d.  the velocity of diffusion
 e.  the thickness of the membrane

16. You just knew I was going to ask it, so here it is!   Assume that you have isolated cells with an intracellular osmotic pressure of 300 mOsM.  Now you place some of those cells into each of the following solutions.  Characterize the osmicity and tonicity of the solutions relative to the 300 mOsM cytoplasm:
 
 

Solution	Osmicity	Tonicity
100 mM NaCl	_______________________	_______________________
150 mM CaCl2	_______________________	_______________________
300 mM sucrose	_______________________	_______________________
400 mM sucrose	_______________________	_______________________

16.  continued
Now if you place those same cells into a solution of 300 mM of solute X (it does NOT ionize in solution) and the cells swell and then soon burst, what do you know about the physical nature or property of solute molecule X:

___________________________________________________________________

17. Characterize the following reaction by circling the correct choices below:

Catabolic	or	anabolic
G = +686 kcal/mole	or	G = -686 kcal/mole
S is increasing	or	S is decreasing
H is negative	or	H is positive
Exergonic	or	endergonic
Endothermic	or	exothermic

18. List THREE pieces of evidence that support the endosymbiotic origin of mitochondria:

 1. ______________________________________________________

 2.  ______________________________________________________

 3.  ______________________________________________________

19. List FOUR characteristics of EUKARYOTIC cells that distinguish them from prokaryotic cells:

 1. ______________________________________________________

 2.  ______________________________________________________

 3.  ______________________________________________________

 4.  ______________________________________________________

20. We are going to examine the uptake of two solute molecules, V and M, into human red blood cells.  Before we begin, assume one solute molecule will enter by simple diffusion while the other enters by a carrier-mediated mechanism.  Fill in the following graph (next page) with two curves, one for simple diffusion (LABEL it D) and a second curve for the carrier mediated uptake (LABEL it C).  Do not worry about or use the data; just draw the curves in the correct shapes:

• Now go the graph above and indicate and label the Ka value for the correct curve.  Be sure to place the Ka on the correct axis.

• What are the units of Ka?  ____________________________

• If we introduce another solute molecule with a higher Ka, it will be transported faster or slower than the first one you plotted above?
___________________

Now examine the data:
 

Initial [solute] in mM	Rate of uptake of solute V (mmoles/min)	Rate of uptake of solute M (mmoles/min)
2	0.6	0.1
4	1.2	0.2
6	1.8	0.3
8	2.4	0.4
10	3.0	0.5
12	3.0	0.6
14	3.0	0.7

• What is the mechanism by which solute M enters the cells?
______________________________

• What evidence from the data support your answer?

_____________________________________________________________________

• What can you infer about the physical properties of M?

__________________________________________________

• By what two general mechanism(s) could solute V enter?

____________________________________________________________________
• If the entry of V depended upon the external [Na⁺], what specific type of transport would be involved?

___________________________________________________

21. Identify the cellular organelle, specific part or side of an organelle, or intracellular structure where each of the following occur.  BE SPECIFIC!
 
 

a.	synthesis of ribosomal components	____________________
b.	transcription	____________________
c.	synthesis of cytoplasmic proteins	____________________
d.	synthesis of plasma membrane proteins	____________________
e.	site of most of ATP synthesis	____________________
f.	hydrolysis of ingested macromolecules	____________________
g.	receives transport vesicles from ER	____________________
h.	formation of secretory vesicles	____________________