Which of the following statements about proteins and amino acids is incorrect?

Options

A. Proteins have peptide bonds in them
B. Proteins are present in the acid insoluble pool
C. Amino acids form Zwitter ions
D. Pleated structures in proteins form tertiary structure

Answer

To determine which statement about proteins and amino acids is incorrect, let's analyze each of the provided statements step by step.

### Step 1: Analyze the first statement
**Statement:** Proteins have peptide bonds in them.
**Analysis:** This statement is correct. Proteins are polymers made up of amino acids linked together by peptide bonds. A peptide bond forms between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water in the process.

**Hint:** Remember that peptide bonds are the linkages that form the backbone of protein structures.

### Step 2: Analyze the second statement
**Statement:** Proteins are present in acid-insoluble pool.
**Analysis:** This statement is also correct. Proteins are generally insoluble in acidic solutions, which is why they can be found in an acid-insoluble pool. This characteristic is due to the nature of protein structure and interactions.

**Hint:** Consider the solubility of proteins in various pH environments when assessing their behavior in solutions.

### Step 3: Analyze the third statement
**Statement:** Amino acids form zwitterions.
**Analysis:** This statement is correct. Amino acids can exist as zwitterions, which are molecules that have both a positive and a negative charge but are overall neutral. This occurs at a specific pH where the amino group is protonated (NH3+) and the carboxyl group is deprotonated (COO-).

**Hint:** Recall the structure of amino acids and how they can ionize depending on the pH of the solution.

### Step 4: Analyze the fourth statement
**Statement:** A pleated structure in protein forms tertiary structure.
**Analysis:** This statement is incorrect. The pleated structure, specifically the beta-pleated sheet, is part of the secondary structure of proteins, not the tertiary structure. The tertiary structure refers to the overall three-dimensional shape of a protein that is formed by the folding of the secondary structures.

**Hint:** Differentiate between primary, secondary, tertiary, and quaternary structures of proteins to understand their classifications.

### Conclusion
The incorrect statement among the options provided is: **"A pleated structure in protein forms tertiary structure."**

### Final Answer
The incorrect statement is: **A pleated structure in protein forms tertiary structure.**