We eat foods containing sucrose (table sugar), lactose (milk sugar), and cellobiose (disaccharide of cellulose in plants). How many net moles of ATP per mole disaccharide do humans generate from the disaccharides sucrose, lactose, and cellobiose using the glycolytic pathway?Options:1. Sucrose: 4 ATP; Lactose: 2 ATP; Cellobiose: 2 ATP2. Sucrose: 2 ATP; Lactose: 4 ATP; Cellobiose: 2 ATP3. Sucrose: 2 ATP; Lactose: 2 ATP; Cellobiose: 0 ATP4. Sucrose: 6 ATP; Lactose: 2 ATP; Cellobiose: 0 ATP5. Sucrose: 4 ATP; Lactose: 4 ATP; Cellobiose: 0 ATP

Carbohydrates that are obtained through the diet include monosaccharides, disaccharides, and polysaccharides. All the disaccharides and polysaccharides that are obtained through the diet are cleaved by specific enzymes during the digestion process, in order to release their monosaccharide units. These monosaccharide units are then easily absorbed by the cells. Inside the cells, the glucose molecules are metabolized through the glycolytic pathway, which release energy required for cellular activities. Sucrose is a disaccharide that is composed of glucose and fructose units. The glucose molecule enters into the glycolytic pathway and synthesizes 4 ATP and 2 NADH. Since the energy investment phase of glycolysis utilizes 2 molecules of ATP, the net energy yield is 2 ATP and 2 NADH. Fructose is converted into fructose-1-phosphate by the enzyme fructokinase, which utilizes one molecule of ATP. Fructose-1-phosphate is converted into glyceraldehyde and dihydroxyacetone phosphate by the enzyme aldolase B. Glyceraldehyde is converted into glyceraldehyde-3-phosphate by the enzyme triose kinase, which utilizes one molecule of ATP. The entry of one molecule of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate into the glycolytic pathway results in the formation of 2 NADH and 4 ATPs. Since the conversion of fructose into fructose-1-phosphate and glycolytic intermediates utilizes two molecules of ATP, the net ATP yield through fructose is 2 ATP and 2 NADH. Thus, the total number of ATP produced from one molecule of sucrose is 4. Lactose is composed of galactose and glucose units. The net energy yield through the glycolysis of one molecule of glucose is 2 ATP and 2 NADH. Galactose is converted into galactose-1-phosphate by the enzyme galactokinase. During this reaction, one molecule of ATP is consumed. Galactose-1-phosphate is then converted into glucose-1-phosphate by the enzyme uridyltransferase. The glucose-1-phosphate is converted into glucose-6-phosphate by the enzyme phosphoglucomutase, and the glucose-6-phosphate enter into the glycolytic pathway. The entry of glucose-6-phosphate into the glycolytic pathway results in the formation of 2 NADH and 4 ATP. Since one molecule of ATP is consumed during the conversion of galactose into galactose-1-phosphate and the conversion of fructose into fructose-6-phosphate in the energy investment phase, the net energy yield through galactose is 2 ATP and 2 NADH. Thus, the total number of ATP produced from one molecule of lactose is 4 ATP. Since there are no enzymes to digest the glycosidic bonds in cellulose, humans cannot use cellulose and its disaccharide unit cellobiose as an energy source. Thus, the total number of ATP produced from cellobiose is 0 (zero). Answer: 5) Sucrose: 4 ATP; Lactose: 4 ATP; Cellobiose 2 ATP.