A molecule that closely resembles the shape of a substrate for an enzyme would most likely serve as a

Question

A.  noncompetitive inhibitor.
B.  allosteric inhibitor.
C.  competitive inhibitor.
D.  allosteric activator.

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 enzymes and inhibition? What other information is related to the question?

  Choose Answer
  Do you have all the information needed to answer the question?

  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.  competitive inhibitor.

Clarify Question
  What is the key concept addressed by the question?
        · The question asks for you to identify the most likely function of a molecule that closely resembles the shape of the substrate.
What type of thinking is required?
        · You are being asked to take what you already know aboutenzymes and molecular shape and apply your understanding to determine which function is most likely.

  Gather Content
What do you already know about enzymes and inhibition? What other information is related to the question?
        · To solve this problem you’ll need to apply what you know about the different ways thatenzyme inhibition can occur and molecular shape and determine the most likely role for a molecule with similar shape to the substrate. Recall that enzyme function can be inhibited competitively, noncompetitively, and allosterically. Why is the shape of substrate molecules important, and what possible role could a molecule that mimics the substrate’s shape play in enzyme function?

  Choose Answer
  Do you have all the information needed to answer the question?
        · At this point you should have everything you need to answer the question. Remember that enzyme function can be competitively, noncompetitively, and allosterically inhibited. What are the key differences between these methods?
        · Let’s consider noncompetitive inhibition first. Noncompetitive means molecules are not trying to outcompete substrate molecules for the enzyme’s active site. As such, the shape of noncompetitive inhibitors is unlikely to closely match the shape of the substrate molecule.
        · Likewise, allosteric inhibitors, which are noncompetitive by definition, bind at a site remote from the active site to inhibit enzyme function. Again, the shape of allosteric inhibitor is unlikely to closely resemble the shape of a substrate molecule because it doesn’t need to function as a mimic.
        · That leaves competitive inhibition as the only viable option, but why does that make sense? In order to compete for the active site of an enzyme, an inhibitor needs to be able to fit into the same space as a substrate molecule. This means the inhibitor must closely resemble the substrate’s shape in order to inhibit enzyme function.

  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 use your understanding of enzymes and inhibitionto determine what the most likely function would be for a molecule