Phosphorylation means

Options

A. Formation of ATP
B. Formation of glucose
C. Formation of `NADPH_2`
D. Formation of starch

Answer

**Step-by-Step Solution:**

1. **Definition of Phosphorylation**: Phosphorylation refers to the process of adding a phosphate group (PO4) to a molecule, typically a protein or a nucleotide. In the context of energy production, it specifically involves the formation of ATP (adenosine triphosphate).

2. **Understanding ATP**: ATP is known as the energy currency of the cell. It is composed of adenosine and three phosphate groups. When ATP is broken down, it releases energy that can be used for various cellular processes.

3. **Formation of ATP**: The process of phosphorylation occurs when ADP (adenosine diphosphate) combines with an inorganic phosphate (Pi) to form ATP. This reaction is crucial for energy transfer within cells.

4. **Light Reaction in Photosynthesis**: In plants, phosphorylation is particularly important during the light reactions of photosynthesis. Here, light energy is used to convert ADP and inorganic phosphate into ATP, which is then utilized in the dark reactions to synthesize carbohydrates.

5. **Photophosphorylation**: It is important to distinguish between phosphorylation and photophosphorylation. Photophosphorylation specifically refers to the formation of ATP in the presence of sunlight, highlighting the role of light in this energy-producing process.

6. **Conclusion**: Therefore, phosphorylation is the process of forming ATP from ADP and inorganic phosphate, which is essential for energy production in living organisms.