Cellular metabolism is an array of chemical processes that allow an organism to respond to the environment, extract energy, grow, reproduce and maintain itself. Cellular metabolism processes are grouped into catabolic processes, which are involved with energy extraction, and anabolic processes, which involve the use of energy for growth and tissue repair. In the cell, nucleic acids, proteins, carbohydrates and fats are the major molecules involved in cellular metabolism.
Nucleic Acids
The nucleus of a cell -- and sometimes the cytoplasm -- contains nucleic acids, which are the library of information that directs and determines the major functions of the cell. There are two types of nucleic acids in the cell: DNA and RNA. DNA is found in the nucleus and is the template from which RNA is made. RNA is modified to become mRNA shortly after it is made; it leaves the nucleus to the cytoplasm where it is used for protein synthesis.
Proteins
Protein synthesis takes place in the cytoplasm and is facilitated by the mRNA which provides the instructions for making a specific protein. Proteins are simply chains of amino acids. When the body favors the anabolic process in a cell, the synthesis of proteins is increased; anabolic processes are hindered when there is insufficient protein and caloric intake. When energy is low in your body, rather than make proteins using available energy, proteins can be broken down to release energy to the cells -- a catabolic process.
Carbohydrates
Carbohydrates, or starch, are the most readily available energy source for the body; they are quickly metabolized to release energy to the body. Long chained or complex carbohydrates are also known as polysaccharides; they are composed of smaller units called monosaccharaides. Glucose is the preferred and the most important monosaccharide in the body; other monosaccharaides include fructose and galactose. Glycogen is the storage form of glucose.
Fats
Fats, which are contained in adipocytes or fat cells, are primarily the storage form of energy in the body. Each gram of fat provides twice as many calories as proteins or carbohydrates. Fat tends to build up in the body during states of increased calorie and fat intake. A sedentary lifestyle also favors fat buildup since less energy is used by the body. Fats are broken down when the body experiences an insufficient supply of carbohydrates or experiences a problem with carbohydrate metabolism. Dieting to lose weight is one way to establish an insufficiency of carbohydrates; diabetes mellitus is the most important disorder of carbohydrate metabolism.
References
- "Ayushveda": Fat Metabolism
- "Harrison's Principles of Internal Medicine": Kasper M.D., et al.; 2005
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