MCQs

The dense array of host-derived sugar chains on gp120 creates a structural "glycan shield" that hides underlying viral protein epitopes from the host immune system.

Hyaluronic acid is a massive, unsulfated glycosaminoglycan that serves as the central structural spine for large extracellular proteoglycan complexes.

UDP-GlcNAc synthesis requires glucose, glutamine, acetyl-CoA, and UTP, making its concentrations highly responsive to overall cellular nutrient status.

Tunicamycin blocks the transfer of N-acetylglucosamine-1-phosphate onto dolichol phosphate, halting the assembly of the core sugar chain.

Lipoprotein lipase requires ApoC-II as a co-factor to bind and hydrolyze triacylglycerols within chylomicrons and VLDLs.

Dolichol phosphate is a long, polyisoprenoid lipid molecule embedded in the ER membrane that serves as the membrane anchor for building the core glycan.

Without the phosphotransferase enzyme, lysosomal proteins lack the mannose-6-phosphate tag needed for sorting, causing them to be misdirected and secreted.

PI-PLC specifically hydrolyzes the phosphodiester bond within the GPI anchor, releasing the attached glycoprotein from its lipid tail.

Unmodified or poorly glycosylated proteins fail the ER quality control check, remain bound to chaperones, and are targeted for ER-associated degradation (ERAD).

Heavily glycosylated proteins form a protective sugar shield on the inner lysosomal membrane, protecting the peptide bonds from proteases.

Mucins cross-link via disulfide bonds to form large polymeric networks. Their hydrophilic sugar chains then trap water molecules to form a gel.

HDL acts as a vascular scavenger, picking up free cholesterol from peripheral tissues and transporting it back to hepatic tissues.

Unlike template-driven translation, carbohydrate assembly depends on local enzyme concentrations and kinetics, resulting in glycan variations.

The dense, charged sugar chains of the lipopolysaccharide layer form a hydrophilic shield that resists the entry of hydrophobic toxic compounds.

LHCs are pigment-protein chromoprotein complexes where chlorophylls and carotenoids are precisely bound to a protein matrix to capture light.

Without N-linked oligosaccharide chains, nascent polypeptides inside the ER lumen cannot fold properly, triggering the unfolded protein response.

The central axis of a proteoglycan monomer is a core protein, from which numerous long glycosaminoglycan chains extend outwards.

Ferritin is a hollow metalloprotein shell that stores iron atoms safely as ferric oxide mineral cores, preventing oxidative cellular damage.

Many nucleoporins are modified with single O-linked N-acetylglucosamine (O-GlcNAc) residues, which are essential for pore function and transport regulation.