Enzyme vs. Hormone

Difference Between Enzyme And Hormone


Enzymes are biological molecules that control the chemical reactions occurring within living organisms. Although many reactions proceed spontaneously in the environment, they are slow and are usually associated with a variety of other reactions, resulting in a large mixture of products. Furthermore, spontaneous reactions like the rusting of iron (an oxidation reaction) are uncontrolled, occurring whenever conditions are suitable. Other reactions proceed only when additional energy, such as from fire, is supplied.

Enzymes make chemical reactions more amenable to life in three ways. First, they accelerate them to the point that the reactions can proceed even at moderate temperatures, such as 37° C (98.6° F) in humans. Second, the reactions can be turned on and off as needed. Third, they do not produce unnecessary side products. By means of this control thousands of enzymes function coordinately within all bacteria, plants, and animals.


Hormone, a chemical messenger that regulates an organism’s biological functions. Active at very low concentrations, hormones trigger a specific cellular activity only after binding to a receptor protein associated with the target cell. Hormone-producing glands, composing the body’s endocrine system, influence four basic categories of vertebrate physiology: sexual development and reproduction, growth and development of tissues and organs, regulation of available energy and heat, and regulation of the body’s internal balance between concentrations of water and ions.

Hormones were initially regarded solely as chemicals secreted directly into the bloodstream, by endocrine glands, to act some distance from the hormonal source. Although these characteristics apply to the so-called endocrine hormones, including compounds produced by the gonads and the pituitary, pineal, thyroid, thymus, and adrenal glands, the definition of hormone has since been broadened to recognize a variety of locally acting substances, called paracrine hormones, secreted from a number of sources, such as brain, heart, liver, and blood cells.



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