Cytoplasm
From Freepedia
Cytoplasm is a homogeneous, generally clear jelly-like material that fills cells. The cytoplasm consists of cytosol and the cellular organelles, except the nucleus. The cytosol is made up of water, salts and organic molecules and many enzymes that catalyze reactions. The cytoplasm plays an important role in a cell, serving as a "molecular soup" in which the organelles are suspended and held together by a fatty membrane. It is found within the plasma membrane of a cell and surrounds the nuclear envelope and the cytoplasmic organelles.
Contents |
Components of the cytoplasm
The aqueous component of the cytoplasm (making up 80 percent of it) is composed of ions and soluble macromolecules like enzymes, carbohydrates, different salts and proteins, as well as a great proportion of RNA. The cytoplasm's watery component is also known as hyaloplasm.
The watery component can be more or less gel-like or liquid depending on the milieu's conditions and the activity phases of the cell. In the first case, it is named cytogel and is a viscid solid mass. In the second case, called cytosol, is a liquid in movement. In general, margin regions of the cell are gel-like and the cell's interior is liquid.
The insoluble constituents of the cytoplasm are organelles (such as the mitochondria, the chloroplast, lysosomes, peroxysomes, ribosomes), several vacuoles, cytoskeletons as well as complex membrane structures (e.g. endoplasmic reticulums or the golgi apparatus).
Differences between animal and vegetal cytoplasm
While all cells possess a cytoplasm, cells from different biological domains can differ widely in the characteristics of their cytoplasms. In the animal kingdom, cytoplasm occupies nearly half the cell's volume while in plant cells, the cytoplasm occupies much less space because of the presences of vacuoles.
Function
The cytoplasm plays a mechanical role, i.e. (example) to maintain the shape, the consistency of the cell and to provide suspension to the organelles. It is also a storage place for chemical substances indispensable to life. Vital metabolic reactions take place here, for example anaerobic glycolysis and protein synthesis.
