The enzyme, sucrose synthase, catalyses the synthesis of sucrose from:

Options

A. UDPG + fructose
B. UDPF + glucose
C. UDPG + glucose-6-phosphate
D. UDPG + fructose-6-phosphate

Answer

To answer the question regarding the enzyme sucrose synthase and the substrates it uses to synthesize sucrose, we can break down the process step by step:

### Step-by-Step Solution:

1. **Identify the Enzyme**: The enzyme in question is sucrose synthase. This enzyme is crucial in the synthesis of sucrose.

2. **Understand the Substrates**: Sucrose synthase catalyzes the synthesis of sucrose from two specific substrates: uridine diphosphoglucose (UDPG) and fructose 6-phosphate.

3. **Chemical Reaction**: The reaction can be summarized as follows:
- **Substrates**: UDPG + Fructose 6-phosphate
- **Product**: Sucrose

4. **Mechanism of Action**: Sucrose synthase facilitates the transfer of a glucose unit from UDPG to fructose 6-phosphate, resulting in the formation of sucrose. This reaction is favored due to the low affinity of the substrates, allowing for a rapid synthesis of sucrose.

5. **Location of Reaction**: This reaction occurs in the cytosol of the plant cells, where both sucrose and its substrates are present.

6. **Conclusion**: Therefore, the correct substrates for the enzyme sucrose synthase to synthesize sucrose are UDPG and fructose 6-phosphate.

### Final Answer:
The enzyme sucrose synthase catalyzes the synthesis of sucrose from **uridine diphosphoglucose (UDPG) and fructose 6-phosphate**.

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