MCQs

Phytochrome is a chromoprotein with a light-sensitive bilin prosthetic group that acts as a molecular switch for plant photomorphogenesis.

Collagen is a structural glycoprotein; its triple-helix structure contains short carbohydrate chains attached to hydroxylysine residues.

ABCA1 is required to load cholesterol onto ApoA-I to form HDL; its absence causes HDL deficiency and lipid buildup in tissues.

GPI anchors use a complex bridge made of a phospholipid linked via a phosphodiester bond to an oligosaccharide, which then binds the protein.

This structural packaging arranges DNA strands systematically inside the eukaryotic nucleus, compacting the genetic material.

Ovalbumin is a storage glycoprotein that makes up the bulk of egg white, providing essential amino acids and attached carbohydrates.

The carbohydrate arrays on glycoprotein hormones are essential for maintaining proper folding, structural stability, and receptor activation.

Standard glycolipids feature small oligosaccharide chains, whereas bacterial LPS molecules possess highly complex, extended carbohydrate structures.

snRNPs ("snurps") are specialized nucleoproteins that combine to build the spliceosome, the machinery that removes non-coding introns.

Apolipoproteins act as structural scaffolding, activate lipid-processing enzymes, and serve as cell-surface ligands for target tissue receptors.

Phosphoproteins, like milk casein or egg vitellin, are generated when phosphate groups attach covalently to serine, threonine, or tyrosine.

Without working receptors, cells cannot internalize LDL particles via receptor-mediated endocytosis, causing cholesterol to build up in the blood.

Both classes contribute to the structural cell coat by projecting their hydrophilic branched sugar chains into the extracellular space.

Cerebrosides are monoglycosylceramides, meaning they utilize a sphingosine amino alcohol base instead of a glycerol backbone.

The oligosaccharide chains on circulating glycoprotein hormones shield them from rapid hepatic filtration and enzymatic degradation.

An apoprotein (or apoenzyme) is the purely proteinaceous part of a conjugated molecule that remains inactive or incomplete without its partner.

Phospholipids align with their hydrophilic heads facing the watery plasma and their hydrophobic tails pointing inward toward the fat core.

Rhodopsin is a conjugated light-sensitive chromoprotein consisting of the protein opsin covalently bound to the carotenoid retinal.

While N-linked glycosylation begins in the rough ER, O-linked sugar modification is localized almost entirely within the Golgi complex.