Brown adipose tissue (BAT) is specialized in thermogenesis, the production of heat, to maintain body temperature in response to cold exposure. Unlike white adipose tissue (WAT), which primarily stores energy in the form of triglycerides, BAT contains abundant mitochondria and is highly vascularized, making it metabolically active. The thermogenic activity of BAT is attributed to the presence of uncoupling protein 1 (UCP1), also known as thermogenin, which is embedded in the inner mitochondrial membrane. Thermogenin functions by uncoupling oxidative phosphorylation. Instead of allowing the proton gradient generated by the electron transport chain (ETC) to drive ATP synthesis, UCP1 facilitates the flow of protons back into the mitochondrial matrix, dissipating the gradient as heat. This process is activated in response to norepinephrine signaling, which triggers lipolysis and the release of free fatty acids that activate UCP1. The role of BAT and UCP1 extends beyond thermoregulation; studies suggest that BAT activity may improve metabolic health by increasing energy expenditure, making it a potential therapeutic target for obesity and metabolic disorders. However, excessive or uncontrolled activation of BAT thermogenesis may pose risks, such as increased oxidative stress or wasting of metabolic substrates. Which of the following best describes the primary role of thermogenin (UCP1) in brown adipose tissue?

Flavin adenine dinucleotide (FAD) is a cofactor involved in various enzymatic redox reactions. Which one of the following enzymes does NOT use FAD as a cofactor?  

Which of the following scenarios would likely result in the greatest increase in HMG-CoA reductase activity?

What is the best analytical technique to detect and quantify a complex mixture of compounds in biofluids?

Which of the following steps in glycolysis is reversible, and why are reversible steps critical for regulating the pathway?

Which of the following is the most appropriate treatment approach for managing diabetic ketoacidosis (DKA)?  

When a 16-carbon fatty acyl-CoA undergoes β-oxidation followed by the citric acid cycle, the following molecules are produced: 8 acetyl-CoA, 16 CO₂, and 64 electrons. Based on this process, how many electrons are produced from the β-oxidation of stearic acid assuming the same route? ?

Positive HCG is a urinary test for determining presence of the hormone human chorionic gonadotropin.

Substernal means above the breastbone.

Insufficient oxygen in the tissue is called hypoxia.