Glycolysis is a process that breaks down glucose into 2 pyruvate molecules. Glycolysis occurs in some stages. Look at Glycolysis Phase
Stage 1 Glucose entering the cell is phosphorylated with the help of hexokinase enzyme to form glucose 6-phosphate. The reaction requires energy which is obtained from the conversion of ATP into ADP.
Stage 2 Phosphoglucoisomerase converts glucose 6-phosphate into its isomer, fructose 6-phosphate
Stage 3 The enzyme phosphofructokinase uses another ATP molecule to transfer a phosphate group to fructose 6-phosphate to form fructose 1, 6-biphosphate.
Stage 4 Fructose 1,6-biphosphate (6 carbon molecules) is broken down into 3 carbon molecules, namely glyceraldehide-8- phosphate (G3P or PGAL).
Stage 5 Each glyceraldehide-3-phosphate changes into lr3-biphosphoglycerate (PGAP) by triose phosphate dehydrogenase. In this stage, there also occurs electron transfer so that NAD changes into NADH. and the binding of, anorganic phosphate from cytoplasm.
Stage 6 The change of 1,3-bisphosphate- glycerate into 3-phosphoglycerate (PGA) occurs by the help of phosphoglycerokinase. In the stage, the formation of 2 ATP molecules also occurs by using available phosphate group in the previous stage.
Stage 7 The change of 3-phosphoglycerate into 2-phosphoglycerate occurs because phosphoglyceromutase relocates its phosphate group.
Stage 8 The change of 2-phosphoglycerate into 2-phosphoenol-pyruvate (PEP) occurs because of enzyme enolase's help which releases 2 water molecules.
Stage 9 2-phosphoenol pyruvate changes into pyruvic acid with the help of pyruvatkinase enzyme and produces 2 ATP molecules
Based on those stages, from the first to the fourth stages are energy utilization stages producing 2 ATP. Meanwhile, from the fifth to the ninth phases are energy production phases producing 4 ATP. It can be concluded that a single glucose molecule in glycolysis produces a total of 2 molecules of pyruvic acid, 2 molecules of ATP, and 2 molecules of NADH. Then, each pyruvic acid is ready to enter Krebs cycle in mitochondria
The Input And Output At Glycolysis