AAMC FL Practice Exam

What is the primary role of phosphorylase in biochemical processes?

1. Removed phosphate groups

2. Add phosphate from ATP

3. Add phosphate from inorganic phosphate

4. Degrade proteins

The correct answer is: Add phosphate from inorganic phosphate

Phosphorylase plays a crucial role in the biochemical process of glycogen breakdown, where it catalyzes the addition of inorganic phosphate to glycogen. This process results in the enzymatic release of glucose-1-phosphate from the glycogen polymer, enabling the organism to mobilize stored energy efficiently. The addition of the phosphate group occurs without the involvement of ATP, making it distinct from other phosphorylation processes. This specificity of phosphorylase is fundamental to metabolic pathways, especially during periods of energy demand when glucose needs to be swiftly converted into usable forms. The activity of phosphorylase is tightly regulated by various factors, including hormonal signals, ensuring that glucose is available when required by the body.