Where do the enzymes of glycolysis operate, and what is its principal end product under anaerobic conditions?

### Why this is right Glycolytic enzymes are located in the cytoplasm. When oxygen is limited, lactate dehydrogenase reduces pyruvate to lactate, using reduced nicotinamide adenine dinucleotide (NADH) and restoring nicotinamide adenine dinucleotide (NAD+). ### The concept Glycolysis breaks glucose into two three-carbon pyruvate molecules. Fermentation is the subsequent reaction that disposes of pyruvate and regenerates NAD+, allowing glycolysis to keep producing energy without oxygen. ### The other options - **B. Mitochondrial matrix; citrate**: Citrate is made in the mitochondrial tricarboxylic acid cycle, not by anaerobic glycolysis. - **C. Cytoplasm; acetyl coenzyme A (acetyl-CoA)**: Acetyl-CoA is formed from pyruvate during aerobic metabolism. - **D. Mitochondrial matrix; glucose**: Glucose is a starting substrate, not the anaerobic end product. ### Terms - **NADH**: Reduced nicotinamide adenine dinucleotide, an electron carrier. - **NAD+**: Nicotinamide adenine dinucleotide, the oxidized form of that carrier. - **Acetyl-CoA**: An activated two-carbon group carrier. ### Remember Glycolysis occurs in the cytoplasm; anaerobic pyruvate becomes lactate.