Aging as a passive process involves the breakdown of structures and the resulting slowing of functions. At the molecular level, passive aging is seen as the degeneration of the elastin and collagen proteins of connective tissues. These proteins are primarily responsible for the smoothness and firmness of young skin. Consequently, when these proteins breakdown, the skin will sag, and the muscle will lose its firmness.

Another sign of passive aging is the breakdown of lipids at the biochemical level. As aging membranes leak during this

lipid degeneration, a fatty, brown pigment known as lipofuscin accumulates. As this happens, the mitochondria, or the "powerhouse of the cell" begins to break down, thereby decreasing the amount of energy that is being supplied to the cell.

This cellular degeneration may be set into action by highly reactive chemicals known as free radicals. These molecules have an unpaired electron in the outermost valence shell. This causes the molecule to grab electrons from other molecules, setting into motion a chain reaction that destabilizes them, and causes death of the cell. These free radicals are the normal by-product of metabolism, and can also form due to exposure to radiation or toxic chemicals. Enzymes that usually inactivate these free radicals diminish in later years, thus increasing their danger.

The active process of aging involves new activities or the appearance of new substances. This process actually begins at birth, as certain cells begin to die. As the cells die

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Approximate Word count = 664
Approximate Pages = 3 (250 words per page double spaced)