What are the key steps in glycolysis?

Glycolysis is a crucial metabolic pathway that takes place in the cytoplasm of cells. It is the first stage of cellular respiration and involves the breakdown of glucose into pyruvate to produce energy in the form of ATP. Here are the key steps in glycolysis:

Step 1: Glucose phosphorylation

The first step involves the phosphorylation of glucose to glucose-6-phosphate. This reaction is catalyzed by the enzyme hexokinase and requires the input of one ATP molecule.

Step 2: Isomerization

Glucose-6-phosphate is then converted to fructose-6-phosphate through an isomerization reaction catalyzed by the enzyme phosphoglucose isomerase.

Step 3: Phosphorylation

Fructose-6-phosphate is further phosphorylated to fructose-1,6-bisphosphate with the help of the enzyme phosphofructokinase-1, using another ATP molecule.

Step 4: Cleavage

Fructose-1,6-bisphosphate is then cleaved into two 3-carbon molecules, dihydroxyacetone phosphate, and glyceraldehyde-3-phosphate by the enzyme aldolase.

Step 5: Energy production

Glyceraldehyde-3-phosphate is oxidized and phosphorylated to form 1,3-bisphosphoglycerate, which generates NADH and ATP through a series of reactions including the enzyme glyceraldehyde-3-phosphate dehydrogenase.

Overall, glycolysis is a series of enzymatic reactions that efficiently breaks down glucose to produce ATP, NADH, and pyruvate, serving as a critical pathway for energy production in cells.