Question

Primary cell wall has protein rich in

• A. Glycine
• B. Hydroxyproline
• C. Histidine
• D. Arginine

Answer 1

The correct option is B Hydroxyproline

The plant cell wall is approximately 0.2$\mu$m thick and completely coats the outside of the plant cells plasma membrane. Because a major function of a plant cell wall is to withstand the osmotic turgor pressure of the cell, the cell wall is built for lateral strength. It is arranged into layers of cellulose microfibrils which are bundles of long, linear, extensively hydrogen bonded polymers of glucose in $\beta$-glycosidic linkages embedded in a matrix composed of pectin and hemicellulose. As much as 15% of the cell wall may be composed of extensin, a glycoprotein that contains abundant hydroxyproline and serine. Most of the hydroxyproline residues are linked to short chains of arabinose and the serine residues are linked to galactose.

So, the correct answer is 'Hydroxyproline'