Question

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 the following are possible components of glycosaminoglycans? Select all that apply. Determine which of the following statements about glycosaminoglycans are true. There is more than one true statement; select all the true statements. Dermatan sulfate and keratan sulfate are examples of glycosaminoglycans. Because glycosaminoglycans consist of only two residues, they generally have low molecular weights. Dextran is an example of a glycosaminoglycan. Glycosaminoglycans are heteropolysaccharides composed of repeating disaccharide units. The amino groups of the amino sugar derivatives provide a positive charge that offsets the negative charges from the sulfate or carboxylate groups.

Answer 1

Answer:

Here’s what I find.

Explanation:

A. Dermatan sulfate and keratan sulfate are examples of glycosaminoglycans (GAGs). TRUE.

They are both long unbranched polymers in which the repeating unit is a disaccharide consisting of a uronic sugar and an N-acetylated amino sugar.

D. Glycosaminoglycans are heteropolysaccharides composed of repeating disaccharide units. TRUE.

A heteropolysaccharide contains two or more monosaccharides, and GAGs contain  a hexoseuronic acid and an N-acetylhexosamine.

B. FALSE. GAGs consist of only two residues, but they are the disaccharide units in a polymer chain that has a molecular weight greater

than 2.5 × 10^6 u.

C. FALSE. Dextran is a polysaccharide of glucose.

E. FALSE. The amino groups in the amino sugars are acetylated, so they are acetamide derivatives. Amides (Kb = 10^-15) are much less basic than amines (Kb = 10^-5), so they are not protonated.