Physiology MCQs Glycoproteins

Q-1. Characteristics of glycoprotein
a) Protein linked with glycosidic bond
b) Core protein
c) Sugar residues are long in carbohydrate portion of glycoprotein
d) Participate in cell surface recognition

Answer: a and d
Glycoproteins are integral membrane proteins. Like glycolipids, they have short carbohydrate chains covalently attached that are exposed on the outer surface of the cell.
Integral proteins are those which penetrate the hydrophobic region of the plasma membrane.
Most integral proteins are trans-membrane proteins which span the entire plasma membrane.
Glycosylation, the attachment of sugar moieties to proteins, is a post-translational modification that provides greater proteomic diversity.
Post-translational modification is characterized by various glycosidic linkages, including N-, O- and C-linked glycosylation, glypiation and phospho-glycosylation.
Glycoproteins play a crucial part in cell-cell recognition, and have important roles in protection and the immune response, reproduction, structural integrity and cell adhesion.

Q-2. Regarding proteoglycans false is
a) Chondroitin sulfate is a proteoglycan
b) They hold less amount of water
c) They are made up of sugar and amino acids
d) They carry charge

Answer: They hold less amount of water
Proteoglycans are glycosylated proteins which have covalently attached highly anionic glycosaminoglycans.
The major biological function of proteoglycans derives from the physicochemical characteristics of the glycosaminoglycan component of the molecule, which provides hydration and swelling pressure to the tissue enabling it to withstand compressional forces.