Which of the following organic compounds are present in acid insoluble fraction but are not strictly biomacromolecules ?

Options

A. Nucleic acids
B. Nucleic acids
C. Proteins
D. Lipids

Answer

To solve the question of which organic compounds are present in the acid insoluble fraction but are not strictly biomacromolecules, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Acid Soluble and Insoluble Fractions**:
- When living tissue is treated with trichloroacetic acid, it separates into two fractions: acid soluble and acid insoluble.
- The acid soluble fraction contains biomolecules that are soluble in acid, typically smaller molecules or monomers.
- The acid insoluble fraction contains larger molecules or polymers, which are generally referred to as biomacromolecules.

2. **Identifying the Organic Compounds**:
- The options given are nucleic acids, amino acids, proteins, and lipids.
- Nucleic acids and proteins are considered biomacromolecules because they are large polymers made up of nucleotides and amino acids, respectively.
- Amino acids are monomers and are part of the acid soluble fraction.
- Lipids, while they can be large structures, often exist as smaller units (like fatty acids) and can form structures like membranes that are insoluble in acid.

3. **Analyzing Lipids**:
- Lipids are unique because they can be found in the acid insoluble fraction due to their structural role in cell membranes.
- When cell membranes break, they form vesicles that are insoluble in acid, thus placing lipids in the acid insoluble fraction.
- However, lipids are not classified as biomacromolecules in the same way proteins and nucleic acids are.

4. **Conclusion**:
- Among the given options, lipids are present in the acid insoluble fraction but are not strictly biomacromolecules.
- Therefore, the correct answer is **lipids**.

### Final Answer:
The organic compound that is present in the acid insoluble fraction but is not strictly a biomacromolecule is **lipids**.