Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
Illustration of the two types of vesicle transport, exocytosis and endocytosis. Endocytosis and exocytosis are types of vesicle transport that carry very large molecules across the cell membrane.


Question: Endocytosis and exocytosis are types of vesicle transport that carry very large molecules across what structure?
cell membrane
Cell membrane.