Feedback for Multiple Choice Quiz 32

  1. These are important generalizations to remember, but even better is to think through the rationale of each of these features for regulation.

  2. All metabolic reactions are enzyme-catalyzed. The speed and specificity are both required, but so is the control. Uncatalyzed (i.e. chemical) reactions in the cell are nearly always deleterious, e.g. toxic reagents, DNA-modifying reactions, etc.

  3. Peptide hormones act outside the cell at specific receptors. In contrast the steroid class of hormones enter the cell before binding to their respective receptor molecules.

  4. This is the prototype of a large (and still growing) number of protein phosphorylation cascade pathways.

  5. The name in the correct answer is the explanation.

  6. This is true in plants and animals. A related generalization is that NADH is primarily a mitochondrial coenzyme whereas NADPH is the cytosolic reducing agent.

  7. Although the first three are used to regulate biological pathways they are not used to communicate between these two. Fructose 1,6 bis phosphate is a metabolite in glycolysis. F2,6 bis phosphate regulates the conversion betwen F6P and F1,6P.

  8. All of these are hallmarks of opposing pathways. A great example is glucolysis and gluconeogensis. Many of the steps are the same, however the interconversion of F-6-P to F-1,6-P is accomplished by different enzymes that are regulated in the opposite fashion. Most organisms can degrade glucose as well as synthesize it from pyruvate. Humans cannot convert acetyl-CoA to pyruvate.
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  Incorrect answers have the "red-lit" button next to your choice.