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Nitrogen in Life and Death
| Article
# : |
10948 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
5 / 1993 |
2,451 Words |
| Author
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Harold Goldwhite
Harold Goldwhite is professor of chemistry at California
State University, Los Angeles. |
The earth's atmosphere is made up of two major gases: oxygen (about 21 percent) and nitrogen (about 78 percent). Oxygen, which exists as O2 molecules (containing two linked oxygen atoms), is reactive and combines readily with hydrocarbons to release usable energy while nitrogen exists as N2 molecules and is not reactive.
Daniel Rutherford, a Scottish medical student, is usually credited with the discovery of nitrogen in 1772. It was, however, French chemist Antonio Lavoisier who first recognized the gas as an element. He showed the parallels between the burning of fuel and the utilization of food in the human body. In both processes the oxygen in the air combines with carbon and hydrogen compounds to generate heat; and in both, the nitrogen in the air remains essentially unchanged. Air deprived of oxygen is almost pure nitrogen and cannot support life. For this reason Lavoisier named this gas azote (from the Greek root meaning "lifeless"), the name it is still known by in French.
Despite this etymology, nitrogen is an element essential to life. Chemical analysis shows that all living matter is made up of only a handful of elements, the most important being carbon, hydrogen, oxygen, and nitrogen.
Proteins--the primary constituents of muscle tissues and enzymes, the ubiquitous catalysts that facilitie the chemical reactions that allow living systems to function--are made up of long chains of nitrogen--containing amino acids. The chemical structure of an amino acid is the grouping--CH(NH2)COOH; the NH2 is the amino function. The genetic materials DNA, which encodes the genetic information, and RNA, which transports the information, are large molecules made up of repeating units of the type--B-C-P--where B is a cyclic molecule containing nitrogen; C is a carbohydrate molecule; and P is a phosphate group. The critical role of nitrogen in living matter is clear from this analysis, and furthermore, all plants and animals require nitrogenous foods in order to grow properly.
Nitrates and gunpowder
The name nitrogen was coined in 1790 from "nitre" plus the suffix "-gen" to mean "nitre-forming" to indicate the presence of the element in nitre also known as ordinary saltpeter or potassium nitre (KNO3).
In nature, saltpeter occurs as colorless crystals or as a white powder on the earth's surface. Probably the oldest chemical industry, saltpeter
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