Which amino acids are concentrated in the polypeptide chains of type I collagen?

Type I collagen, the most abundant form of collagen in the human body, has a specific amino acid composition that is crucial for its structural integrity and function. Glycine, proline, and hydroxyproline are the primary amino acids that are particularly concentrated in the polypeptide chains of type I collagen.

Glycine is the smallest amino acid and is found at every third position in the collagen helix. This repetitive structure is essential for the tight packing of the collagen triple helix, contributing to the strength and structural stability of the collagen fibers. Proline and hydroxyproline are also heavily represented; proline contributes to the rigidity of the helical structure, while hydroxyproline plays a role in stabilizing the collagen triple helix through hydrogen bonding. The presence of these three amino acids is fundamental for the unique properties of type I collagen, enabling it to effectively support tissues such as skin, bone, and tendons.

This specific composition is what makes option B the correct choice, as it accurately reflects the amino acids that are integral to the structure and functionality of type I collagen polypeptide chains.