Glycolysis is the first step in cellular respiration. Which option best summarizes the process?
Glycolysis is the process in which one molecule of glucose is broken down into two molecules of pyruvate, producing a small amount of ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide). This process occurs in the cytoplasm of the cell and does not require oxygen.
Glycolysis is the initial step of cellular respiration, which is the process that converts glucose into energy in the form of ATP (Adenosine Triphosphate). Here is a step-by-step summary of glycolysis:
1. Glucose Activation: The process begins with the activation of glucose using two molecules of ATP. This step converts glucose into fructose-1,6-bisphosphate.
2. Cleavage: Fructose-1,6-bisphosphate is then split into two three-carbon molecules known as glyceraldehyde-3-phosphate (G3P).
3. Energy Capture: For each G3P molecule, two molecules of NAD+ are reduced to form NADH, while one molecule of ATP is produced through substrate-level phosphorylation. This step converts G3P into 1,3-bisphosphoglycerate.
4. ATP Production: In this step, 1,3-bisphosphoglycerate donates a phosphate group to ADP, forming ATP and producing 3-phosphoglycerate.
5. Conversion: 3-phosphoglycerate is converted into 2-phosphoglycerate through the transfer of a phosphate group.
6. Rearrangement: 2-phosphoglycerate is then transformed into phosphoenolpyruvate (PEP) by removing a water molecule.
7. ATP Generation: PEP donates a phosphate group to ADP to produce ATP and pyruvate.
At the end of glycolysis, two molecules of pyruvate are generated along with a net gain of two ATP molecules and two NADH molecules. These pyruvate molecules can further enter the next steps of cellular respiration if oxygen is available or undergo fermentation in the absence of oxygen.