Q. 31 The glycosylation of the proteins occurs in ____ .
(A) glyoxysomes
(B) lysosomes
(C) Golgi apparatus
(D) plasma membrane
Protein glycosylation is a key post-translational modification where carbohydrates attach to proteins, aiding folding, stability, and cell signaling. For the query “The glycosylation of proteins occurs in ____”, the correct answer is (C) Golgi apparatus.
Correct Answer
Glycosylation primarily happens in the endoplasmic reticulum (ER) for initial N-linked steps and matures in the Golgi apparatus for O-linked glycosylation and processing. Among the options—glyoxysomes, lysosomes, Golgi apparatus, plasma membrane—the Golgi apparatus is the key site for completing glycosylation.
Option Breakdown
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(A) Glyoxysomes: These organelles exist in plant germinating seeds for lipid conversion to sugars via glyoxylate cycle; they lack glycosylation enzymes.
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(B) Lysosomes: These degrade macromolecules using hydrolytic enzymes; no role in protein glycosylation, which is synthetic.
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(C) Golgi apparatus: Correct. It modifies N-glycans from ER and adds O-linked sugars, forming mature glycoproteins for secretion or membrane use.
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(D) Plasma membrane: Hosts some glycosyltransferases for minor modifications but not primary glycosylation site.
