Final answer:
Brown-fat mitochondria uncouple oxidative phosphorylation to produce heat, which is vital for thermoregulation in certain animals and newborn babies. This process involves the use of uncoupling proteins that allow for energy release as heat instead of ATP production.
Step-by-step explanation:
Brown-fat mitochondria have a unique characteristic that allows them to produce heat as an adaptation for thermal regulation. This process is known as the uncoupling of oxidative phosphorylation, where the electron transport chain continues to function, but the synthesis of ATP is bypassed. Instead, proteins called uncoupling proteins (like thermogenin) allow protons to re-enter the mitochondrial matrix without passing through ATP synthase, which is normally required for ATP production. The energy that would have been used to produce ATP is instead released as heat energy, making it a thermogenic process.
Therefore, brown-fat mitochondria uncouple oxidative phosphorylation to produce C. heat. This is crucial in organisms that require heat production for thermoregulation, such as in certain cold-adapted animals and newborn babies who have higher surface area to mass ratios, leading to more rapid heat loss.