Quiz 9 Key
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An answer may be used more than once for each section.

1-2. Classify each carrier as a/n (A) antiport; (S) symport; or (U) uniport.

    U        GLUT1 (glucose transporter)

    U        Ca2+ ATPase

    A        Na+–K+ ATPase

    S          Na+–glucose carrier

    A        HCO3–Cl carrier

 

3-4. Classify the same carriers as performing (R) primary active transport;
(E) secondary active transport; (D) diffusion, not active transport.

     D       GLUT1 (glucose transporter)

     R       Ca2+ ATPase

     R       Na+–K+ ATPase

     E       Na+–glucose carrier

     D       HCO3–Cl carrier

 

5-6. Answer with (C) acetylcholine receptor; (E) epinephrine receptor; (I) insulin receptor; or (L) all three receptors.

     C       a gated ion channel

     L       an integral membrane protein

     I       an enzyme (a kinase)

     C       has helices that rotate

     E      activates an enzyme indirectly

     E       desensitized by β-arrestin

7-10. Answer with (A) adenylyl cyclase; (G) Gα; (P) protein kinase A; or (R) 7tm receptor.

     A       converts ATP to cAMP

     G       activated by binding the receptor

     G       converts GTP to GDP

     R       activated by binding epinephrine

     P       converts ATP to ADP

     P       activated by binding cAMP

     R       not an enzyme

     A       activated by binding Gsα

    R, A      an integral membrane protein

     G       Its inactive form is heterotrimeric.

     G       a lipid-anchored membrane protein

     P       Its inactive form has 4 subunits.

     P       a protein in the cytosol

     P       inactivated when cAMP → AMP

     A       synthesizes a second messenger

     G       inactivated when GTP → GDP

 

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