In Lesson 5, you'll explore the structure and function of one of the cell's most crucial parts: the plasma membrane. All life depends on this very important boundary between a cell and its environment! You'll start by examining the membrane's components and unique properties, which are perfectly suited to protecting the health and well-being of the cell. Then you'll take a look at the important jobs the membrane does for your cells, including screening materials, moving stuff in and out of the cell, and receiving messages. Finally, you'll see how materials cross the plasma membrane and why that's important to normal health. Along the way, you'll gain a better understanding of blood types, diabetes, and cystic fibrosis.