Major Structural Components of the Cell Membrane

Lesson Transcript
Instructor: Dominic Corsini

Dominic Corsini has an extensive educational background with a B.S. in Secondary Biology and General Science with a Minor in Environmental Education, an M.Ed. in Educational Leadership, an M.S. in Biology, and a K-12 Principal Certification Program. Corsini has experience as a high school Life, Earth, Biology, Ecology, and Physical Science teacher.

What are cell membranes and how are they constructed? What do the pieces of a cell membrane do? This lesson will answer these questions by investigating major membrane components. Updated: 06/10/2020

What Are Cell Membranes?

Let's begin this lesson with a question: what do all cells have in common? Truth be told, there are several characteristics cells all share, things like basic metabolism or having genetic material. But for the purposes of this lesson, we'll focus on the fact that all cells contain a cell membrane.

The cell membrane is the outer covering of a cell, and it's responsible for controlling entry and exit of material from the cell. Cell membranes, regardless of whether they exist in plants, animals, fungi or bacteria, are all made of the same basic components. These components are phospholipids, proteins, carbohydrates and cholesterol or sterols.

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  • 0:00 What Are Cell Membranes?
  • 0:46 Phospholipids
  • 1:26 Proteins
  • 1:56 Carbohydrates
  • 2:14 Cholesterol
  • 2:41 Lesson Summary
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The first major component of the cell membrane is the phospholipid. Phospholipids are amphipathic fats that form the majority of the membrane. In the cell membrane below, the red pieces with the two yellow tails are phospholipids.

Phospholipids are the red pieces with two yellow tails.
diagram of cell membrane

They are arranged in a double layer so that the tails face inward. This arrangement works because the head of the phospholipid is hydrophilic and immerses itself inside the watery environment inside and outside the cell. The fatty acid tails are hydrophobic and are repelled by water. By sandwiching the fatty acid tails within the membrane, it keeps them away from water while simultaneously immersing the heads in water.


Proteins form another integral part of the cell membrane. Proteins are large molecules formed from long chains of amino acids. You'll notice that there are many different types of proteins. These proteins perform functions such as moving materials across the membrane. For example, have you ever heard that eating bananas will help protect you from getting cramps? That's because bananas contain potassium. This potassium is moved into your cells by proteins embedded in the cell membrane.


The third major component of cell membranes is carbohydrates. Carbohydrates are other large molecules that are made from simple sugars. These molecules generally allow cells to communicating, such as through acting as sites where chemical signaling molecules, such as hormones, can attach to the cell. Carbohydrates also act like a name tag for cells and allow cells to identify each other as part of a larger multicellular organism.

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