The reaction mechanism proceeds by first adding an additional phosphate group to the 2' position of the 3 phosphoglycerate. The enzyme then removes the phosphate from the 3' position leaving just the 2' phosphate, and thus yielding 2 phsophoglycerate. In this way, the enzyme is also restored to its original, phosphorylated state.
The eighth step involves the conversion of 2 phosphoglycerate to phosphoenolpyruvate (PEP). The reaction is catalyzed by the enzyme enolase. Enolase works by removing a water group, or dehydrating the 2 phosphoglycerate. The specificity of the enzyme pocket allows for the reaction to occur through a series of steps too complicated to cover here.
The final step of glycolysis converts phosphoenolpyruvate into pyruvate with the help of the enzyme pyruvate kinase. As the enzyme's name suggests, this reaction involves the transfer of a phosphate group. The phosphate group attached to the 2' carbon of the PEP is transferred to a molecule of ADP, yielding ATP. Again, since there are two molecules of PEP, here we actually generate 2 ATP molecules.
We have now completed our discussion of the steps of glycolysis. If we go back and take count of our ATP usage and generation, we find that we have consumed two molecules of ATP and generate four to leave a net gain of two ATP molecules from the glycolytic pathway. We have gone from our starting product, glucose, to our final product, pyruvate.