Final answer:
The three most common glycosaminoglycans are hyaluronic acid, chondroitin sulphate, and dermatan sulphate; they are critical components of the extracellular matrix and contribute to the structure and function of connective tissues.
Step-by-step explanation:
The three most common glycosaminoglycans (GAGs) are hyaluronic acid, chondroitin sulphate, and dermatan sulphate.
Glycosaminoglycans are long unbranched polysaccharides consisting of repeating disaccharide units which are commonly sulfated and found covalently linked to core proteins to form proteoglycans. These components are critical for the structure and function of the extracellular matrix found in connective tissues. For example, hyaluronic acid, one of the GAGs, occurs in large amounts in the synovial fluid, skin, and vitreous humor of the eye, providing lubrication and resistance to compression.