Proteoglycans are part of the extracellular matrix; they provide structure, viscosity and lubrication, and adhesiveness. They are composed of proteins conjugated to carbohydrate components called glycosaminoglycans. The glycosaminoglycan component makes up the majority of the mass of a proteoglycan. Which of these are possible components of glycosaminoglycans

This question lacks options, options are:  a. beta-D-fructofuranose b. amylose c. uronic acid d. N- acetylglucosamine. The correct answers are c and d.

Explanation:

Glycosaminoglycans are very long, unbranched polysaccharides, made up of repeating units of disaccharides. One of the disaccharides is always an amino sugar, which can be N- acetylglucosamine. The other is uronic acid (it can be iduronic acid or glucuronic acid and is often sulfated at position 2). The amino sugar is usually sulfated and the rest of the sugars have carboxyl groups, which give the structure a negative charge, which attracts a large amount of cations such as sodium. Glycosaminoglycans are often covalently bound to proteins to form proteoglycans. Hyaluronic acid is the only glycosaminoglycan that does not form protein bonds and does not have sulfate groups in its structure.

the fossil record provides evidence of a common ancestor to many species.