Quiz 4 Key
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1-4. Use these types of enzymes: (O) oxidoreductase; (H) hydrolase; (I) isomerase;
                                                     (T) transferase; (Y) lyase; (G) ligase.

    O     converts Fe2+ to Fe3+

   G    forms a bond using ATP to provide energy

   H    breaks a bond by adding H2O to it

   Y    adds a functional group to a C=C bond

   H    synthesizes a bond by          removing H2O

   Y    removes a functional group,
         creating a C=C bond

    I     rearranges the structure of a
          molecule

   T    transfers a functional group from one
          molecule to another

5-8. For exam 4 we will study the enzyme that catalyzes this reaction.

The enzyme requires the coenzymes FAD and TPP.
Use the letters from 1-4 as well as these: (S) substrate; (P) product;
                                                          (C) co-substrate coenzyme; (R) prosthetic coenzyme

 O,Y,T   one type of enzyme this could be

      R        FAD

I,G,H one type of enzyme this could not be

      R       TPP

     S       pyruvate

      C      CoA-SH

      P      CO2

      P       AcCoA

      C      NAD+

9-10. Underline the value for the least favored (least spontaneous) reaction and circle the most favored.

ΔG°′ = – 2,000 J/mol

Keq = 137

Keq = 0.62

ΔG°′ = 13,000 J/mol

Keq = 137

ΔG°′ = 3,000 J/mol

ΔG°′ = 3,000 J/mol

Keq = 137

9-10. Underline the value for the least favored (least spontaneous) reaction and circle the most favored.

Keq = 0.062

ΔG°′ = 3,000 J/mol

ΔG°′ = - 20,000 J/mol

Keq = 1.37

ΔG°′ = 6,900 J/mol

Keq = 0.298 = 0.30

Keq = 3200

ΔG°′ = –780 J/mol

Comment: I added the complementary values to make the choices clearer, but I didn't expect you to do any calculations. Instead I hoped that the answers would be fairly obvious. What was clear was that most students are more comfortable with ΔG than with Keq. Oh yes, also note the units.

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