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Definition: protein from The Penguin Dictionary of Psychology

Any long-chain polymer of AMINO ACIDS. Proteins are integral components of the protoplasm of every cell, provide the amino acids that an organism cannot produce by itself and are an essential part of nutrition. The term ‘complete protein‘ is used for those that contain all the essential amino acids needed for growth, maintenance and repair of bodily tissue.

protein

From The Columbia Encyclopedia
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight. Hundreds of protein molecules have been isolated in pure, homogeneous form; many have been crystallized. All contain carbon, hydrogen, and oxygen, and nearly all contain sulfur as well. Some proteins also incorporate phosphorous, iron, zinc, and copper. Proteins are large molecules with high molecular weights (from about 10,000 for small ones [of 50–100 amino acids] to more than 1,000,000 for certain forms); they are composed of varying amounts of the same 20 amino acids , which in the intact protein are united through covalent chemical linkages called peptide bonds. The amino acids, linked together, form linear unbranched polymeric structures called polypeptide chains; such chains may contain hundreds of amino-acid residues; these are arranged in specific order for a given species…
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Full text Article protein

From Library of Health and Living: The Encyclopedia of Nutrition and Good Health
A complex polymer of amino acids; the most common material in the body. The word protein is derived from the Greek word proteios , meaning “foremost” or “of primary importance.” Perhaps as many as 100,000 different types of proteins make up 50 percent of the dry matter of the body. All life…
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Full text Article Proteins

From Gale Encyclopedia of Nursing and Allied Health
Diagram of the structure of a protein.
Proteins are linear chains of amino acids connected by chemical bonds between the carboxyl group of each amino acid and the amine group of the one following. These bonds are called peptide bonds, and chains of only a few amino acids are referred to as polypeptides rather than proteins. Proteins are…
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Full text Article Protein

From The Gale Encyclopedia of Nutrition and Food Labels
Protein is an important component of every cell in the body. Proteins are composed of compounds of carbon, hydrogen, oxygen, and nitrogen, which are arranged as strands of amino acids. Some amino acids cannot be made in the body and must be obtained from diet. Food proteins, known as dietary…
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Full text Article Protein

From The Gale Encyclopedia of Diets
Sources of protein. (Illustration by Electronic...
Protein is the major functional and structural component of every cell in the body. Proteins are composed of compounds of carbon, hydrogen, oxygen, and nitrogen, which are arranged as strands of amino acids. Nine of these amino acids cannot be synthesized to meet the body's needs and must be…
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Full text Article Protein

From The Gale Encyclopedia of Fitness
Proteins are compounds made up of carbon, hydrogen, oxygen, and nitrogen that are arranged as strands of amino acid. They play an essential role in the maintenance of cells, growth, and functioning of the human body. Serving as the basic structural molecule of all the tissues in the body, protein…
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Full text Article proteins

From Collins Dictionary of Medicine
Large molecules consisting of up to thousands of AMINO ACIDS linked together by peptide bonds to form polypeptides which, in turn, are linked to form proteins. These long chains of amino acids are often folded in specific ways. Fibrous proteins, such as COLLAGEN , are formed from spiral strand…
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Full text Article protein

From The Columbia Encyclopedia
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight. Hundreds of protein molecules have been isolated in pure, homogeneous form; many have been…
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Full text Article protein

From Penguin Dictionary of Biology
Polymer of very large or enormous molecular mass, composed of one or more polypeptide chains, and whose monomers are AMINO ACIDS , joined together (in condensation reactions) by PEPTIDE BONDS . In addition, some have covalent ‘sulphur bonds' formed by oxidization between two cysteine radicals in the…
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Full text Article protein

From The Chambers Dictionary
any member of a group of complex nitrogenous substances that are an important constituent of the bodies of plants and animals, eg compounds of carbon, hydrogen, oxygen, nitrogen, usu sulphur, often phosphorus, etc, their molecules consisting of one or several polypeptide chains, each of which is a…
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Full text Article protein

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Large, complex, biologically important macromolecule composed of hundreds of amino acids joined by peptide bonds to form chains. Most organisms use combinations of 20 standard amino acids, which can be joined in any order. Proteins are essential to the functioning of living organisms. As enzymes…
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