Which of the following is not true in relation to glycoproteins -

Glycoproteins are proteins to which oligosaccharides are covalently attached. The oligosaccharide chains of glycoproteins lack a serial repeating unit; this is in contrast to the carbohydrate chains in proteoglycans that consists of repeating disaccharide units (amino sugar and acid sugar). The carbohydrate unit of glycoproteins is different and the heterogeneity among glycoproteins is due to the difference in sugar component. Carbohydrate chain is often branched in glycoproteins.