Plant Cell Walls-1  
311 Syllabus

Introduction  (Chapter 15)

The Cell Wall is an External  Matrix Secreted by the Cell.

The Protoplast is the Plasmalemma and everything inside of it.

The Apoplast is composed of Everything Outside of the Plasmalemma. This includes all Cell Walls & Intercellular Spaces

Protoplasts are interconnected via Plasmodesmata that traverse adjacent Cell Walls.

The Symplast includes the interconnected Protoplasts within a Tissue or Organ.

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An understanding of the Apoplast and Symplast is of fundamental importance!

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The Cell Wall is like a tight Cotton sweater.

The sweater is made from yarn which readily absorbs water.

Although the Sweater fits snugly, it can be removed without damaging your skin.

This cell has an intact Wall. You can see the Cellulose Fibrils that form the  wall. These are like the yarn in a sweater.	The Cell Wall has been partly removed to reveal the Plasmalemma which lies beneath it.

The Sweater is outside of your body, just as the Cell Wall is outside of the Protoplast.

Back in the 50's college students tried to see how many people could cram into a telephone booth. Imagine that they are all wearing body sweaters (this was another craze in the 50's). Even though all of their bodies were pressed together they did not actually touch one another. Their sweaters did touch one another. Their sweaters would constitute the major part of the Apoplast.   Even though their bodies are extremely close together, there are some air spaces between them. These air spaces are also part of the Apoplast

Their bodies are each Protoplasts. All of their protoplasts would constitute the Symplast of the phone booth.

What would happen if a prankster opened the top of the telephone booth and started pouring colored water onto the sweaters of those on top?

The water would pass freely through the Sweaters (Apoplast) but would be repelled by the skin (Plasmalemmas) of the Symplast.