Collagen contains an amino acid that is a modified form of the naturally occurring amino acid.
a. Name the natural amino acid.

Verified step by step guidance

1. Step 1: Understand the context of the problem. Collagen is a structural protein in the body, and it contains a modified form of a naturally occurring amino acid. The question asks us to identify the natural amino acid that is modified in collagen.
2. Step 2: Recall that the most common modified amino acid in collagen is hydroxyproline. Hydroxyproline is derived from the natural amino acid proline through a post-translational modification process.
3. Step 3: Recognize that proline is a naturally occurring amino acid with the chemical formula C₅H₉NO₂. It is unique because its side chain forms a cyclic structure, making it an imino acid.
4. Step 4: Understand that the modification involves the addition of a hydroxyl (-OH) group to the proline molecule, specifically at the 4th carbon of the pyrrolidine ring, resulting in hydroxyproline.
5. Step 5: Conclude that the natural amino acid associated with the modified form in collagen is proline.

Key Concepts

Collagen Structure

Collagen is a structural protein that is a major component of connective tissues in the body. It is composed of amino acids, primarily glycine, proline, and hydroxyproline. The unique triple-helix structure of collagen provides strength and support to tissues, making it essential for skin, bones, and cartilage.

Amino Acids

Amino acids are organic compounds that serve as the building blocks of proteins. There are 20 standard amino acids, each with a specific side chain that determines its properties. Among these, glycine is the simplest and most abundant amino acid in collagen, playing a crucial role in its stability and structure.

Hydroxyproline

Hydroxyproline is a modified form of the amino acid proline, formed by the addition of a hydroxyl group. This modification is critical for collagen stability, as it allows for the formation of hydrogen bonds between collagen fibers, enhancing the structural integrity of connective tissues. Hydroxyproline is not found in significant amounts in most proteins, making it unique to collagen.