Cellular Basics

Cell Responses

How do substances move in and out of cells?

Cells constantly transport substances across their cell membranes. Endocytosis (from the Greek endo, meaning “in,” and cytosis, meaning “cell”) is the process by which cells bring molecules into their structure. Exocytosis (from the Greek exo, meaning “out,” and cytosis) is the process by which cells transport materials out of their structure across their own cell membrane.