Energy, Enzymes, and Metabolism

Metabolism includes all the reactions in an organism. Catabolic and anabolic pathways (series of reactions) intertwine to breakdown molecules (often the food we eat) to provide energy or to use energy to build up biomolecules.

Getting into bioenergetics a little more, we’ll need to understand those energy transformations. In particular, the concept of energy coupling of reactions, which then involves understanding how proteins work.

Try these questions. Publish your answers in the comments to one, some or all.

1. How would you label the three components (a, b, and c) of the ATP molecule in the image below?
2. In the image above, which bond(s) is/are likely to break? And, name the chemical mechanism by which this bond is broken.
3. Explain why this reaction releases so much energy.
4. In the figure illustrating an exergonic reaction below, indicate the correct labels for a-e.
5. Both ATP and ADP serve as regulators of enzyme activity. In catabolic pathways, which of these two molecules would you predict acts as an inhibitor? Which one acts as an activator?
6. Why are catabolic and anabolic pathways often coupled in a cell?
7. When a cell breaks down glucose, only about 34% of the energy is captured by ATP. According to the 2nd law of thermodynamics, what happens to the other 66% of the energy?
8. In reference to enzymes and substrates, what is meant by an “induced fit”?
9. When substance A was added to an enzyme reaction, product formation was decreased. The addition of more substrate did not increase product formation. What could substance A be?