Final answer:
The Golgi apparatus is the organelle that forms transport vesicles by pinching off portions of its membrane to aid in the transportation of proteins and lipids within the cell.
Step-by-step explanation:
The organelle that pinches off portions of its membrane to form a transport vesicle is known as the Golgi apparatus.
The Golgi apparatus is a vital component in the cell's process of transporting proteins and lipids. It is an organelle that consists of flattened membrane sacs known as cisternae. The apparatus receives newly synthesized proteins and lipids from the endoplasmic reticulum (ER), modifies them, and sorts them. Then, it packages the substances into vesicles. These vesicles are membranes that enclose certain substances and are essential for the transport of materials within the cell. The membranes of these vesicles can fuse with the plasma membrane or the membranes of other organelles. Importantly, the Golgi apparatus facilitates the movement of molecules within the cell by forming transport vesicles that deliver proteins and lipids to their required locations, working somewhat akin to a cellular post office.