The cell membrane is semipermeable (or selectively permeable). It is made of a phospholipid bilayer, along with other various lipids, proteins, and carbohydrates. Image of the plasma membrane, showing the phospholipid bilayer with peripheral and integral membrane proteins, glycoproteins (proteins with a carbohydrate attached), glycolipids (lipids with a carbohydrate attached), and cholesterol ...
So just to remind us what a cell membrane actually is, a cell membrane is made up of little things that look like this, which are called phospholipids. And they come together and form what we call a lipid bilayer. So over here, I've pre-drawn a lipid bilayer. And it'll look something like this. It'll be made up a lot of these small ...
