Cell membranes are made from many different molecules; however, the most pertinent is arguably the lipid.
This lesson will discuss which type of lipid forms the majority of the membrane. A brief quiz and summation are included.
What are Cell Membranes?
What do cells and fats have in common? At first these things might seem unrelated, but without fats you probably wouldn’t have cells.
Sound peculiar? Let’s explore this connection further. Most of us recognize that living things are composed of cells. In fact, millions of specialized cells exist and perform various functions to keep you alive. But all these cells are not identical. Some cells work within your muscles, others help absorb nutrients, and still others form your skeleton.
Yet despite these differences there are things that all cells have in common; they all contain a cell membrane. Cell membranes are the outer covering of cells, and they help control entry and exit of material from the cell. See the outer covering of this animal cell? That’s the cell membrane.
Phospholipids have two main parts, a phosphate head and two fatty-acid tails.
The phosphate head is the red/pink part seen above, and the fatty acid tails are yellow. The major lipids in cell membranes, the phospholipids, are arranged in a bi-layer. A bi-layer is another way of describing the double layer of phospholipids that comprise the cell membrane.
The bi-layer exists because the fatty acid tails are hydrophobic, meaning they fear water, and the phosphate heads are hydrophilic, meaning they love water. Water can be found both inside and outside the cell. However, by sandwiching the hydrophobic fatty acid tails between hydrophilic phosphate heads you’re able to immerse the heads in water while simultaneously insulating the tails from water. This means the phospholipid experiences the best of both worlds.
All cells need to control what enters and exits them. For this they rely on their cell membranes.
Cell membranes are the outer coverings of cells. All cells possess and build these membranes out of lipids. Lipids are collections of molecules that include fats, waxes, sterols, and certain vitamins.
Within a cell membrane, the primary type of lipid used is the phospholipid. Phospholipids form the majority of our cell membranes and are made from two primary parts. These parts are the hydrophilic phosphate head and the hydrophobic fatty acid tail. Hydrophilic means water loving, while hydrophobic means water fearing.