What is a polypeptide? Give one example.

Explanation

### Step-by-Step Solution

1. **Definition of Polypeptide**: A polypeptide is a linear chain of amino acids that are linked together by peptide bonds (also known as amide bonds).

2. **Formation of Peptide Bonds**: When two amino acids come together, a reaction occurs where the carboxyl group of one amino acid reacts with the amino group of another. During this reaction, a molecule of water (H2O) is released, and a peptide bond (–CONH–) is formed between the two amino acids.

3. **Length of Polypeptide**: A polypeptide is typically defined as a chain of 50 or more amino acids. The sequence and number of amino acids in the chain determine the specific properties and functions of the polypeptide.

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