HNF 150 Exam 2 Review - HNF 150 Exam 2 Review Proteins and...

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HNF 150 Exam 2 Review Proteins and Amino Acids Structure of proteins and amino acids The structure of proteins enables them to perform many vital functions. One key difference from carbohydrates and fats is that proteins contain nitrogen atoms in addition to the carbon, hydrogen, and oxygen atoms that all three energy-yielding nutrients contain. These nitrogen atoms give the name amino (which means “nitrogen containing”) to the amino acids , the building blocks of proteins. All amino acids have the same simple chemical backbone consisting of a single carbon atom with both an amine group (the nitrogen-containing part) and an acid group attached to it. Each amino acid also has a distinctive chemical side chain attached to the center carbon of the backbone. Essential amino acids Essential amino acids are those amino acids that either cannot be synthesized at all by the body or cannot be synthesized in amounts sufficient to meet physiological need. Of the 20 amino acids, some are essential and some are essential only in special circumstances. Conditionally essential amino acid is an amino acid that is normally nonessential but must be supplied by the diet in special circumstances when the need for it exceeds the body’s ability to produce it. What makes different proteins different? Each type of protein has a distinctive sequence of amino acids and so has great specificity. Often, cells specialize in synthesizing particular types of proteins in addition to the proteins necessary to all cells. Protein digestion and absorption Digestion of protein involves denaturation by stomach acid, then enzymatic digestion in the stomach and small intestine to amino acids, dipeptides, and tripeptides. The cells of the small intestine complete digestion, absorb amino acids and some larger peptides, and release them into the bloodstream for use by the body’s cells.
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Roles of protein in the body Acid-base balance. Proteins help maintain the acid-base balance of various body fluids by acting as buffers. Antibodies. Proteins form the immune system molecules that fight diseases. Blood clotting. Proteins provide the netting on which blood clots are built. Energy. Proteins provide some fuel for the body’s energy needs. Enzymes. Proteins facilitate needed chemical reactions. Fluid and electrolyte balance. Proteins help to maintain the water and mineral composition of various body fluids. Growth and maintenance. Proteins form integral parts of most body tissues and serve as building materials for growth and repair of body tissues, such as skin, connective tissues, muscles, organs, and bone. Hormones. Proteins regulate body processes. Some hormones are proteins or are made from amino acids. Transportation. Proteins help transport needed substances, such as lipids, minerals, and oxygen, around the body.
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