Chapter 9, Problem 22TYK

Brown fat, which is found in newborn infants and hibernating mammals, has uncoupler proteins that, when activated, make the inner mitochondrial membrane leaky to H⁺. What is the function of brown fat?

1. a. It produces more ATP than does regular fat and is also found in the flight muscles of ducks and geese, providing more energy for long-distance migrations.
2. b. It lowers the pH of the intermembrane space, which results in the production of more ATP per gram than is produced by the oxidation of glucose or regular fat tissue.
3. c. Because it dissipates the proton gradient, it generates heat through cellular respiration without producing ATP, thereby raising the body temperature of hibernating mammals or newborn infants.
4. d. Its main function is insulation in the endothermic animals in which is it common.