Practice Questions

Plant Golgi bodies are often referred to as dictyosomes because they exist as smaller, dispersed stacks within the plant cytoplasm.

The Golgi apparatus accepts vesicles from the ER, performs biochemical modifications, and targets them to their final cellular destinations.

The active sites of lipid synthesis enzymes face the cytosol, adding new lipid molecules directly to the cytosolic leaflet of the SER.

Ribophorins I and II are structural glycoproteins found uniquely on the RER membrane that secure ribosomes in place during synthesis.

Because COPII vesicles carry cargo forward (anterograde), blocking them causes proteins to pile up within the ER.

Glucose-6-phosphatase is a resident enzyme of the SER membrane, playing a key role in regulating blood glucose levels.

The Sec61 complex forms the physical protein-conducting channel (translocon) across the RER membrane. Blocking it halts co-translational translocation.

BiP (Binding Immunoglobulin Protein) uses ATP to mask exposed hydrophobic regions on nascent proteins, preventing aggregation and helping them fold properly.

New lipids are added to the cytosolic leaflet of the ER. Scramblases flip lipids randomly across leaflets without needing energy, balancing out the bilayer surface area.

The Signal Recognition Particle halts translation temporarily to prevent premature protein folding in the cytosol before docking at the RER translocon.