Transport across cell membranes

Question 1

What is the function of the cell membrane?

Answer 1

The cell membrane controls entry and exit of molecules to cell.

Question 2

What is the cell membrane composed of?

Answer 2

The cell membrane is composed of a phospolipid (fat) bilayer (2 layer of phospolipids) with protein molecules spread amongst them.

Question 3

what does the structure of the cell membrane look like?

Answer 3

It is called the fluid-mosaic model. It is fluid like due to constant movement of the phospholipid bilayer. It is also mosaic due to patchy distributions of proteins throughout the phospholipid bilayer.

Question 4

Name the functions of protein molecules in the membrane:

Answer 4

Channel forming proteins aid diffusion of small molecules.
Carrier proteins to actively transport molecules across the membrane.
Structural proteins that provide structure for the membrane.
Enzymes to speed up chemical reactions in the membrane.
Receptors for antibodies or for hormones.