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Cytoplasm

Cytoplasm is the material that fills cells. It's a homogeneous, mostly clear jelly-like substance consisting of cytosol and the cellular organelles with the exception of the nucleus. Cytosol is composed of water, salts, organic molecules, and the many enzymes necessary for the cell to catalyze reactions. Without cytoplasm, the different molecules in the cells could not get to the different sites at which they're needed.

80% of the cytoplasm is aqueous and composed of ions and soluble, primarily organic, macromolecules. The aqueous part is also called hyaloplasm. It behaves like a gel sometimes, depending on the activity phase of the cell; in this state, it is called cytogel. When instead it behaves like a liquid, it's called cytosol. Most cells have cytoplasm behaving both ways, with the gel-like portions on the outer rims of the cell.

The 20% of the cytoplasm that is not aqueous is made up of organelles, mitochondria, chloroplasts, vacuoles, the cytoskeleton, and complex membrane structures like the endoplasmic reticulum.

In a plant, the cytoplasm occupies considerably less space in cells than in animals; this is largely because of vacuoles. In animals, the more cytoplasmic structure of the cell lends flexibility. The cytoplasm is necessary for maintaining cellular shape and consistency and for providing suspension to organelles. It's also a storage area for life-supporting chemicals.

Web Resources On Cytoplasm

Structure and Functions of Cytoplasm
Cytoplasm Encyclopedia Entry

Book Resources On Cytoplasm

Between Nucleus and Cytoplasm by Paul Agutter
The cytoplasm of the plant cell by Alexandre Guilliermond

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