Final answer:
The first step of glycolysis involves the enzyme hexokinase phosphorylating glucose to form glucose-6-phosphate. Simultaneously, high-energy electrons are extracted from glyceraldehyde-3-phosphate and picked up by NAD+, producing NADH.
Step-by-step explanation:
The first step of glycolysis involves the enzyme hexokinase phosphorylating glucose, forming glucose-6-phosphate. This reaction is exergonic, meaning it releases energy. Simultaneously, high-energy electrons are extracted from the sugar glyceraldehyde-3-phosphate and picked up by the electron carrier NAD+, producing NADH. The sugar is then phosphorylated by the addition of a second phosphate group, forming 1,3-bisphosphoglycerate.