What is a Vacuole? - Parts of a Cell
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What is a Vacuole?

pink cell with darker pink circles inside it
Vacuoles in an amoeba (a one-celled eukaryote)

September 2016 - Vacuoles are little pockets in the cytoplasm of a cell where a cell stores food. You can see them with a good light microscope. Vacuoles are mostly made of water and amino acids.

They have a lipid membrane around them to keep out the salty water of the cytoplasm. Simple cells and prokaryotes generally don't have vacuoles, so vacuoles probably evolved along with the first eukaryotic cells around two billion years ago. Probably they started out when part of the lipid membrane around the cell folded in and then pinched itself off to form a new little membrane inside the cell.

All plant cells have vacuoles. Plant cells use the vacuoles to keep things in, just the way you might use plastic bags. Sometimes the cell puts garbage or poisons or broken parts of the cell or extra water inside a vacuole. Sometimes the cell keeps food in a vacuole (like hydrocarbon molecules that it will break down later for food). Sometimes plant cells use vacuoles like water balloons to stiffen one part of the cell and give it a more useful shape. Some plant cells are almost all taken up by vacuoles.

A video showing a paramecium
forming vacuoles and ejecting waste

Most animal cells also have vacuoles, but not all of them. Animal cells use vacuoles to get rid of garbage, and also to get rid of extra water.

The way the DNA in the nucleus tells the cell to put something into a vacuole is by using enzymes as messengers. The cell can use the vacuole to get rid of things it doesn't want. To do this, the cell puts the garbage inside the vacuole. Then the vacuole moves over to the edge of the cell, and merges with the cell membrane. Once it has a door to the outside, the vacuole opens up and spits out the garbage, and then it seals itself up, and separates from the cell wall again.

Learn by Doing - Soap bubble project
Parts of a Cell

Bibliography and further reading:

Parts of a Cell
Quatr.us Home

Studying the parts of a cell

A good light microscope will let you see vacuoles for yourself.

These high quality Pustefix soap bubbles let you do a project with vacuoles.

Or get my personal favorite, the bubble bear! Squeeze, and the blower pops out of his head! Also from Pustefix.

Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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