AP BIOLOGY

Detailed explanation-1: -So, the correct answer is ‘Endoplasmic reticulum’.

Detailed explanation-2: -COPII-coated vesicles transport cargo proteins from the ER to the Golgi; COPI-coated vesicles transport cargo in the retrograde direction (from the cis-Golgi back to the ER) and between Golgi cisternae; and clathrin-coated vesicles form from the plasma membrane and the TGN to fuse with endosomes or lysosomes (Fig.

Detailed explanation-3: -From the endoplasmic reticulum, proteins are transported in vesicles to the Golgi apparatus, where they are further processed and sorted for transport to lysosomes, the plasma membrane, or secretion from the cell.

Detailed explanation-4: -Transmembrane proteins are synthesized by ribosomes – protein-making machines – that are on the surface of a cell compartment called the endoplasmic reticulum. As the new protein is made by the ribosome, it enters the endoplasmic reticulum membrane where it folds into the correct shape.