Practice Questions

Without the mannose-6-phosphate (M6P) tag, lysosomal enzymes miss their sorting receptors in the trans-Golgi, routing into the default secretory pathway instead (I-cell disease).

The trans-Golgi network is the sorting hub where exit vesicles are packaged and targeted to the plasma membrane, lysosomes, or extracellular space.

While N-linked glycosylation begins in the ER, O-linked glycosylation occurs exclusively within the compartments of the Golgi apparatus.

The cisternal maturation model states that cis-cisternae physically mature into medial and then trans-cisternae, receiving recycling enzymes from behind via COPI vesicles.

Golgi apparatus stacks (dictyosomes) synthesize non-cellulosic polysaccharides and send secretory vesicles to form the phragmoplast and cell plate.

COPI-coated vesicles handle retrograde vesicle transport, moving materials backward from the Golgi to the ER.

Primary lysosomes emerge as transport vesicles from the trans-Golgi network carrying concentrated mixtures of active hydrolytic enzymes.

Lysosomal enzymes are specifically modified with a mannose-6-phosphate (M6P) tag in the cis-Golgi, which is recognized by M6P receptors in the trans-Golgi for sorting.

As proteins move from the cis to the trans face, their attached sugar groups undergo sequential enzymatic modifications to form mature complex glycoproteins.

The cis face, or forming face, is oriented toward the endoplasmic reticulum to intercept emerging transport vesicles.