Thylakoid Membrane in Photosynthesis: Definition, Function & Structure Video

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: The Backster Effect

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

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:00 Plant Cell Structure
  • 0:16 Chloroplasts and Thylakoids
  • 0:40 Definition and Function
  • 2:24 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

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Jeremy Battista
Inside of plant cells, there are chloroplasts. Inside the chloroplasts are all of the structures that help plants capture and convert light into energy. The thylakoid membrane is where much of this occurs, and we will discuss its role here.

Plant Cell Structure

Plant cells are eukaryotic, meaning that they have a nucleus and membrane-bound organelles. Most of the organelles will resemble those found in other eukaryotic cells. There are some different organelles, though. One of those organelles is the chloroplast.

Chloroplasts and Thylakoids

Inside the chloroplasts of plant cells, you will find stacks of thylakoids called grana. In some plant cells, thylakoids will not always be stacked. As a brief reminder, thylakoids are membrane-bound compartments inside of the chloroplasts. Thylakoids are the epicenter for photosynthetic light-reactions. They contain the chlorophyll for the plant, which is the light-collecting pigment.

Definition and Function of Thylakoid Membrane

The thylakoids themselves contain the chlorophyll, but the thylakoid membrane, which is the layer that surrounds the thylakoid, is where the light reactions take place. Embedded in the thylakoid membrane are two photosystems, named photosystem I and photosystem II. In each photosystem, there are different proteins and slightly different chlorophyll pigments that allow for different kinds of light absorption.

Photosystem II absorbs the light energy, exciting (energizing) an electron that takes off into the electron transport chain. It moves along this chain (similar to respiration) and gives off energy as ATP (adenosine triphosphate, which is an energy molecule). It arrives at photosystem I and fills in a hole left by an electron that got excited as well.

The second electron will then shoot up and travel down a similar electron transport chain. When it gets to the end of the chain, it meets ferredoxin, which is just a protein that contains iron. It then goes through a redox, or oxidation/reduction, reaction where it bonds to NADP+, creating a different energy molecule, NADPH, to be used to help run the secondary part of photosynthesis, which is known as the Calvin cycle.

To unlock this lesson you must be a 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

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
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? 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