Nitrogen and Phosphorus Essential Elements for Life

Nitrogen occurs in nature where it constitute nearly three fifth of the earth s atmosphere. It also occurs in the combined form as nitrates. Nitrogen is an essential element for living matter because it is an important constituent of proteins and even human body. Phosphorus is also essential for life because its compound control almost all biological processes. 

Nitrogen, oxygen, and phosphorus are essential elements for maintaining life. What essential biological molecules contain these elements ... 

Some elements are essential to the composition or function of the body. Since the body is mostly water, hydrogen and oxygen are obviously essential elements. Carbon (C) is a component of all life molecules, including proteins, lipids, and carbohydrates. Nitrogen (N) is in all proteins. The other essential nonmetals are phosphorus (P), sulfur (S), chlorine (Cl), selenium (Se), fluorine (F), and iodine (I). The latter two are among the essential trace elements that are required in only small quantities, particularly as constituents of enzymes or as cofactors (nonprotein species essential for enzyme function). The metals present in macro amounts in the body are sodium (Na), potassium (K), and calcium (Ca). Essential trace elements are chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), molybdenum (Mo), nickel (Ni), and perhaps more elements that have not yet been established as essential. 

In a departure from the first edition we include here a brief account of selected non-metals and their multiple and various activities in biological systems. We pointed out in Chapter 1 that organic chemistry is the chemistry of hydrocarbons, but that if we restricted ourselves to just hydrogen and carbon, it would be impossible to construct the molecules we know to be essential for life as we know it. To construct proteins, nucleic acids, carbohydrates, and lipids, we also need oxygen, nitrogen, phosphorus, and sulfur. Indeed, we also require, as we saw in Chapter 1, a number of other elements, notably a not-inconsiderable number of metals. 

The continued production of organic matter in the sea requires the availability of the many building blocks of life, including essential major elements such as carbon (C), nitrogen (N), and phosphorus (P) essential minor elements such as iron, zinc, and cobalt and, for many marine organisms, essential trace organic nutrients that they cannot manufacture themselves (e.g., amino acids and vitamins). These required nutrients have diverse structural and metabolic function and, by definition, marine organisms cannot survive in their absence. 

Thirty elements are currently known to be essential for life. The most abundant elements in the human body are hydrogen, carbon, nitrogen, and oxygen, but calcium, phosphorus, sodium, magnesium, potassium, sulfur, and chlorine are also present in large amounts. Other elements found only in trace amounts, such as zinc, are essential for the action of many enzymes. 

Figure 2.24 shows the elements that are essential for life. Over 97% of the mass of most organisms is due to just six elements— oxygen, carbon, hydrogen, nitrogen, phosphorus, and sulfur. 

T Figure 2.24 The elements that are essential for life are indicated by colors. Red denotes the six most abundant elements in living systems (hydrogen, carbon, nitrogen, oxygen, phosphorus, and sulfur). Blue indicates the five next most abundant elements. Green indicates the elements needed in only trace amounts. 

The element phosphorus, like nitrogen, is essential to plant and animal life. Although phosphorus was not identified and isolated until 1669, phosphorus-containing materials have been used as fertilizers since ancient times, usually from bird droppings, fish, and bone. The first phosphoric acid was made by treating bone ashes with sulfuric acid. This marked the beginning of the commercial fertilizer industry. Eventually, mined phosphate rock, a poor fertilizer by itself, was substituted for bones as a raw material for phosphoric acid in the mid-1880s. 

Although phosphorus is in group 15 with some other metalloids, it is usually classed as a nonmetal since it resembles nitrogen somewhat, the element above it in group 15. Both are essential to the biochemical field as vital elements to support life. Phosphorus has 10 known allotropic forms. This is an unusually high number for any element. A system of categorizing the allotropes by three colors has made it easier to keep track of them. These three colors are white, red, and black phosphorus. 

We all know that certain chemical elements, such as calcium, carbon, nitrogen, phosphorus, and iron, are essential for humans to live. However, many other elements that are present in tiny amounts in the human body are also essential to life. Examples are chromium, cobalt, iodine, manganese, and copper. Chromium assists in the metabolism of sugars, cobalt is present in vitamin B12, iodine is necessary for the proper functioning of the thyroid gland, manganese appears to play a role in maintaining the proper calcium levels in bones, and copper is involved in the production of red blood cells. 

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