Chapter 9, Problem 9.1PS

High-Energy Bonds. When first introduced by Fritz Lipmann in 1941, the term high-energy bond was considered a useful concept for describing the energetics of biochemical molecules and reactions. However, the term can lead to confusion when relating ideas about cellular energy metabolism to those of physical chemistry. To check out your own understanding, indicate whether each of the following statements is true (T) or false (F). If false, reword the statement to make it true.

(a) Energy is stored in special high-energy bonds in molecules such as ATP and is released when these bonds are broken.

(b) Energy is always released whenever a covalent bond is formed and is always required to break a covalent bond.

(c) To a physical chemist, high-energy bond means a very stable bond that requires a lot of energy to break, whereas to a biochemist, the term is likely to mean a bond that releases a lot of energy upon hydrolysis.

(d) The terminal phosphate of ATP is a high-energy phosphate that takes its high energy with it when it is hydrolyzed.

(e) Phosphoester bonds are low-energy bonds because they require less energy to break than the high-energy bonds of phosphoanhydrides.

(f) The term high-energy molecule should be thought of as a characteristic of the reaction the molecule is involved in—not as an intrinsic property of a particular bond within that molecule.