When succinyl-CoA is converted into succinic acid, the energy-storing compound formed is

Options

A. ADP
B. GDP
C. AMP
D. GTP

Answer

To solve the question of what energy-storing compound is formed when succinyl-CoA is converted into succinic acid, we can follow these steps:

### Step 1: Understand the Context
The conversion of succinyl-CoA to succinic acid occurs in the Krebs cycle (also known as the citric acid cycle or TCA cycle). This cycle is a key metabolic pathway that generates energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

**Hint:** Remember that the Krebs cycle is a series of reactions that produce energy-rich molecules.

### Step 2: Identify the Reaction
During the conversion of succinyl-CoA to succinic acid, a high-energy thioester bond in succinyl-CoA is broken. This reaction is coupled with the phosphorylation of GDP (guanosine diphosphate) to form GTP (guanosine triphosphate).

**Hint:** Look for the specific reactions in the Krebs cycle where energy transfer occurs.

### Step 3: Recognize the Products
In this specific reaction, the energy released from the conversion of succinyl-CoA to succinic acid is used to convert GDP into GTP. GTP is an energy-storing compound similar to ATP and can be readily converted to ATP.

**Hint:** Focus on the energy-storing compounds that are typically produced during the Krebs cycle.

### Step 4: Conclusion
The energy-storing compound formed when succinyl-CoA is converted into succinic acid is GTP.

**Final Answer:** GTP

### Summary of Steps:
1. Understand the Krebs cycle context.
2. Identify the specific reaction involving succinyl-CoA.
3. Recognize that GDP is phosphorylated to form GTP.
4. Conclude that GTP is the energy-storing compound formed.