University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

289

Pages:

6
Author:

Sheha A.

Glycolysis Glycolysis is the basic breakdown of glucose. In this process, a molecule of glucose is converted into two molecules of pyruvic acid in the cytoplasm of the cell. It is an aerobic process, but it can also take place under anaerobic conditions. Steps: Phosphorylation of Glucose: This is the first step of glycolysis. Glucose is phosphorylated to glucose-6-phosphate with ATP. This reaction is catalyzed by the enzyme hexokinase in the presence of Mg2+. Isomerization: Glucose-6-phosphate is isomerized to fructose-6-phosphate. This reaction is catalyzed by the enzyme phosphoglucose isomerase. 3. Phosphofructokinase-1: Catalyzes the transfer of a phosphate group from ATP to fructose-6-phosphate to form fructose-1,6-bisphosphate. This step is a major regulatory step in glycolysis. 4. Splitting: Fructose-1,6-bisphosphate is split into two 3-carbon molecules: dihydroxyacetone phosphate (a ketone) and glyceraldehyde 3-phosphate (an aldehyde). 5. Phosphoglycerate Kinase: In this step, glyceraldehyde 3-phosphate is oxidized and phosphorylated to form 1,3-bisphosphoglycerate. This is the first energy-yielding step of glycolysis as a high-energy phosphate bond is formed. 6. Substrate-level phosphorylation: 1,3-bisphosphoglycerate loses a high-energy phosphate group to ADP, forming ATP and 3-phosphoglycerate. This is the first instance of substrate-level phosphorylation in glycolysis. 1,3-bisphosphoglycerate is a high-energy compound. 7. Isomerization: 3-phosphoglycerate is converted to 2-phosphoglycerate. This reaction involves the transfer of a phosphate group from the third carbon to the second carbon. 8. Dehydration: 2-phosphoglycerate loses a water molecule, forming phosphoenolpyruvate (PEP). PEP is a high-energy compound. 9. Substrate-level phosphorylation: The last step in glycolysis. PEP transfers its high-energy phosphate group to ADP, forming ATP and pyruvate. This is the second instance of substrate-level phosphorylation in glycolysis.