What is a polypeptide ? Give one example.

Explanation

### Step-by-Step Text Solution:

**Step 1: Definition of Polypeptide**
A polypeptide is a linear chain of amino acids linked together by peptide bonds (also known as amide bonds). These peptide bonds form through a dehydration synthesis reaction, where a molecule of water is released when the amino group of one amino acid reacts with the carboxyl group of another.

**Step 2: Structure of Polypeptide**
Polypeptides can vary in length, typically consisting of 50 or more amino acids. The sequence of amino acids in a polypeptide determines its unique properties and functions. The polypeptide chain can fold into specific shapes, leading to secondary (like alpha helices and beta-pleated sheets) and tertiary structures, which are crucial for the biological activity of proteins.

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