In addition to transporting oxygen red cells also remove C0₂ in the form of [HCO₃]^-, from actively metabolizing cells.  As erythrocytes circulate through tissue capillaries, [HCO₃]^- is picked up and cytoplasmic Cl^- is lost. The reverse processes - [HCO₃]^- efflux and Cl^- uptake - occur in the small capillaries of the lungs where the concentration of C0² is naturally quite low. Consider the membrane mechanism(s) possibly responsible for these transport phenomena and answer the following questions.

A. (6 pts)  Are Cl^- and [HCO₃]^- transport likely mediated by active or passive mechanism(s)?  Which is the more reasonable hypothesis?  Why? 
 
 
 
  
B. (24 pts)  Describe how any three of the following determinations could be made, indicating clearly what the results would show:          
a. whether Cl^-and [HCO₃]^- transports are carrier-mediated?
b. whether a single antiport or two uniport carriers are involved?
c. whether Band 3 or another membrane constituent(s) are involved?
d. whether the transport processes are active or passive?
 
 
 

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