What is the net gain of ATP molecules in alcoholic and lactic acid fermentation , respectively?

Options

A. 2,4
B. 3,2
C. 2,3
D. 2,2

Answer

To determine the net gain of ATP molecules in alcoholic and lactic acid fermentation, we will analyze the processes step by step.

### Step-by-Step Solution:

1. **Understanding Fermentation**:
- Fermentation is the anaerobic breakdown of glucose, meaning it occurs in the absence of oxygen. There are two main types of fermentation: alcoholic fermentation and lactic acid fermentation.

2. **Initial Breakdown of Glucose**:
- The process begins with one molecule of glucose (C6H12O6) which is broken down into two molecules of glyceraldehyde-3-phosphate (PGAL). During this initial step, ATP is consumed.

3. **Conversion of PGAL to Pyruvate**:
- Each PGAL is then converted into pyruvate. This step produces ATP and NADH. For each PGAL converted, one ATP is generated. Since two PGAL are produced from one glucose, this results in a total of 2 ATP molecules generated from the conversion of PGAL to pyruvate.

4. **Net Gain of ATP Before Fermentation Type**:
- At this point, from the breakdown of glucose to pyruvate, a total of 2 ATP molecules have been produced.

5. **Alcoholic Fermentation**:
- In alcoholic fermentation, pyruvate is converted into ethanol and carbon dioxide. During this process, NADH produced in the earlier step is utilized, and NAD+ is regenerated. However, this does not produce any additional ATP.
- Therefore, the net gain of ATP from alcoholic fermentation remains at **2 ATP**.

6. **Lactic Acid Fermentation**:
- In lactic acid fermentation, pyruvate is converted into lactic acid. Similar to alcoholic fermentation, NADH is utilized, and NAD+ is regenerated, but again, no additional ATP is produced.
- Thus, the net gain of ATP from lactic acid fermentation also remains at **2 ATP**.

### Conclusion:
- The net gain of ATP molecules in alcoholic fermentation is **2 ATP**.
- The net gain of ATP molecules in lactic acid fermentation is also **2 ATP**.

### Final Answer:
The net gain of ATP molecules in alcoholic and lactic acid fermentation, respectively, is **2 ATP and 2 ATP**.