In the reaction: C4H6O4 + FAD ®C4H4O4 + FADH2, what type of reaction took place to remove the protons from C4H6O4?

Question

A.  Decarboxylation
B.  Reduction
C.  Dehydrogenation
D.  Oxidation

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

  Gather Content
  What do you already know about redox reactions and electrons? What other information is related to the question?

  Choose Answer
  Do you have all necessary information to what type of reaction is taking place?

  Reflect on Process
  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

C.  Dehydrogenation

Clarify Question
What is the key concept addressed by the question?
        · The question asks you to identify what type of reaction takes place when you remove protons from C4H604.
What type of thinking is required?
        · You are being asked to use what you know about the loss and gain of electrons and protons during redox reactions and extend, or apply, that knowledge to determine what type of reaction takes place when you remove protons from C4H604.

  Gather Content
  What do you already know about redox reactions and electrons? What other information is related to the question?
        · Recall that oxidation-reduction, or redox, reactions occur when electrons are removed from (oxidation) or added to (reduction) a molecule. Remember that cells rely on redox reactions in order to harvest the high potential energy stored in electrons from broken bonds and use it to do work in the cell.
        · During the breaking of bonds in carbohydrate molecules, high-energy electrons are freed. This reaction is also accompanied by the loss of a proton. If you lose a proton and an electron together, does this give you a clue as to what type of reaction is taking place?

  Choose Answer
  Do you have all necessary information to what type of reaction is taking place?
        · Breakdown of carbohydrates by the cell requires multiple steps, many of which involve redox reactions. Several reactions are provided as options. Decarboxylation is unlikely to have happened because nothing is changing to the number of carbons before or after the reaction takes place. A reduction reaction definitely happened, but that was to the FAD molecule, not the C4H604 molecule. C4H604 was also oxidized, but it lost protons as well. Remember that each time an electron is liberated, so too is a proton, which together make hydrogen and thus constitute a dehydrogenation reaction during oxidation. The most accurate answer is dehydrogenation.

  Reflect on Process
  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Answering this question correctly depended on your ability to apply what you know about redox reactions and to identify the type of reaction that took place to remove protons from C4H604.
        · If you got the correct answer, nice job! If you got an incorrect answer, were you able to read the reaction to determine which components had their protons removed? Were you able to see that electrons would also be removed? Were you able to correlate the removal ofthe protons and electrons to determine that a dehydrogenation reaction took place?