Vesicles: Definition & Function

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  • 0:00 What are Vesicles?
  • 0:42 Function and Types of Vesicles
  • 2:04 Lesson Summary
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Lesson Transcript
Derrick Arrington

Derrick has taught biology and chemistry at both the high school and college level. He has a master's degree in science education.

Expert Contributor
Dawn Mills

Dawn has taught chemistry and forensic courses at the college level for 9 years. She has a PhD in Chemistry and is an author of peer reviewed publications in chemistry.

Cells must be able to move molecules, digest particles, and secrete materials in order to survive. For many cellular functions, vesicles are used. In this lesson, we will learn about vesicles and how they are used by cells.

What Are Vesicles?

Cells are the basic building blocks of all living things. In order for organisms to survive, their cells must be able to complete numerous functions. Many of these functions require the cells to move molecules from one part of the cell to the other. When a cell needs to move a molecule many times, it uses vesicles.

Vesicles are cellular organelles that are composed of a lipid bilayer. You can think of vesicles as cellular envelopes that are used to transport materials from one place to another. Vesicles also function in metabolism and enzyme storage as well. This diagram shows the overall structure of a simple vesicle:

Function and Types of Vesicles

Vesicles play many roles within a cell. Since vesicles are composed of a lipid bilayer, they can have a completely self-contained environment that is different from the inside of the cell. There are essentially four types of vesicles used by cells. They are vacuoles, lysosomes, transport vesicles, and secretory vesicles.

Vacuoles are vesicles that contain mostly water. They are able to regulate the pressure and water level of the cell to control the conditions of the internal environment. Plant cells are known to have large vacuoles. This diagram depicts the large vacuole inside a plant cell:

Lysosomes are cellular vesicles that contain digestive enzymes. Lysosomes are used by cells to break down food particles and to get rid of unneeded cellular materials.

Transport vesicles move molecules within the cells. All cells make proteins and require them to function. Proteins are made in ribosomes. When the proteins are made, they are packaged into transport vesicles and moved to the Golgi apparatus, where they can be modified and sorted before being sent to their final destination in the cell.

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Additional Activities


Vesicles can vary in type and function based on their structure and environment. Vesicles are formed naturally during different processes such as secretion, uptake, or when transporting materials. The questions below will help provide you with a greater understanding of vesicles and their function. The discussion section provides more details to check your response to the question prompts.


1. How do vesicles transport substances?

2. Which type of vesicles would be involved in breaking down a toxic compound such as hydrogen peroxide?

3. What type of vesicles contain mostly water? Why?

4. Vesicles can be formed in reaction to an event such as allergic reactions or exposure to poison ivy. What is the function of the vesicles in these instances?


1. Vesicles have the ability to fuse to membrane material because they are composed of phospholipids. This allows them to move substances around the cell and to the membrane.

2. Peroxisomes are vesicles that break down toxic compounds within a cell by using oxygen. The hydrogen peroxide would be broken into water and oxygen molecules. It is interesting to note that hydrogen peroxide is generated by peroxisomes when they are breaking down other toxic compounds.

3. Vacuoles contain mostly water. This is used to regulate osmotic pressure and help in nutrient storage.

4. The function in these instances is more of a response to a trigger, such as exposure to a poison. It is a response that will metabolize a substance generated in the reaction, as well as may be responsible for the transportation of other compounds to the affected area.

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