Copyright

Lipid Bilayer: Definition, Structure & Function

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Bioavailability: Definition, Calculation & Equation

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:00 Plasma Membrane and…
  • 0:28 Phospholipids
  • 1:07 The Need for Lipid Bilayer
  • 3:10 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Timeline
Autoplay
Autoplay
Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: John Williams
The lipid bilayer is important for maintaining the shape of a cell and for selective permeability. Therefore, it is vital for the survival and function of the cell. This article explains what the lipid bilayer is and how its structure contributes to cell viability.

Plasma Membrane and Lipid Bilayer

Cells are outlined by a plasma membrane. The plasma membrane is responsible for protecting the interior of the cell and for selective permeability, which means it monitors what materials enter and exit the cell. The ability of the plasma membrane to determine which materials can move in and out of a cell is due to the molecules found in the membrane and the presence of a lipid bilayer. Let's discuss the properties of the lipid bilayer.

Phospholipids

Phospholipids are the primary molecules found in the plasma membrane. A phospholipid is unique in that it has a hydrophilic region called the head, and a hydrophobic region known as the tail. The hydrophilic region can interact with water due to the presence of a phosphate group which is polar, like water. If something is hydrophilic, that means it likes water. Conversely, the hydrophobic region of the molecule does not interact with water because it is not polar. If something is hydrophobic, that means it does not like water. A molecule that has both partial hydrophilicity and partial hydrophobicity is classified as amphipathic.

The Need for a Lipid Bilayer

The interior of the cell is primarily made of water. Likewise, the exterior of the cell is usually surrounded by watery fluid. This means that the plasma membrane could not possibly consist of just one layer of phospholipids. This is because the hydrophobic (or water fearing) tail region would have to interact with one of the watery regions inside or outside of the cell. So instead, the cells have evolved to have two layers of phospholipids.

The bilayer creates a 'sandwich' style arrangement, where the hydrophilic heads of each layer face the watery environment inside and outside of the cell. This means that the hydrophobic tails are confined to the middle, creating a hydrophobic region between the two layers of heads. This allows for the plasma membrane to be stable in this dual watery environment.

Lipid Bilayer
lipid bilayer

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account
Support