Chapter 6 Protein and Amino Acids Chapter 6 Learning List dietary sources of protein Objectives Describe the elemental components and general structure of an 1 2 3 4 5 6 7 8 9 10 amino acid and the structure of protein Define peptide bond Distinguish between essential nonessential and conditionally amino acids Discuss how the order of amino acids in a polypeptide chain affects protein structure and function of the protein Define denaturation and discuss how this affects the function of a protein List ways in which a protein may be denatured Describe the steps of protein digestion and absorption Discuss the steps involved in protein synthesis Define transamination and deamination Copyright 2010 John Wiley Sons Inc Chapter 6 learning objectives 11 12 13 14 15 16 17 18 19 Identify the functions of proteins in the body Describe nitrogen balance and how is relates to protein needs Identify the RDA for adults and AMDR for protein Knowing an individual s weight calculate their protein requirements based on RDA Identify conditions in which an individual may have increased protein requirements greater than the RDA Describe the conditions under which the body uses protein to produce energy Distinguish kwashiorkor from marasmus List other conditions or problems associated with inadequate protein intake Explain why protein energy malnutrition is more common in children than in adults Copyright 2010 John Wiley Sons Inc Chapter 6 learning objectives 20 21 22 23 24 25 26 Discuss the potential risks associated with a high protein diet Explain how dietary protein can trigger a food allergy Describe celiac disease list the classic symptoms of this condition and the treatment for it List the types of vegetarian diets and define each type Discuss the benefits and risks of vegetarian diets List the nutrients of concern for those who are following a vegan diet Distinguish between complete and incomplete proteins and identify sources of each Copyright 2010 John Wiley Sons Inc Sources of protein Proteins are the predominant structural and functional material in every cell Dietary sources of protein Animal based Meat eggs dairy products Provide B vitamins and some absorbable minerals High in saturated fat and cholesterol Plant based Grains nuts legumes peas peanuts beans soybeans lentils High in fiber phytochemicals and unsaturated fat 2012 John Wiley Sons Inc All rights reserved Sources of Protein in the Diet Copyright 2010 John Wiley Sons Inc Sources of Protein in the Diet Copyright 2010 John Wiley Sons Inc Protein in the Diet Most of the world relies on plant proteins from grains and vegetables Positive relationship between economy of country and dietary intake of animal protein in that country Protein deficiency is rare in the United States In the US about two thirds of dietary protein comes from meat poultry seafood eggs and dairy products Copyright 2010 John Wiley Sons Inc Structure of Proteins Proteins contains carbon hydrogen oxygen and a unique element Nitrogen Elemental component of proteins are amino acids Structurally each amino acid has Acid group COOH Amine group NH2 Unique side chain Essential and Nonessential Amino Acids Twenty different amino acids found in proteins Nine amino acids are essential Eleven amino acids are nonessential Can be synthesized in the body from other amino acids or by adding nitrogen to C containing structures Some amino acids are conditionally essential amino acids cannot be made in body in adequate amounts under certain conditions Amino Acids and Protein Structure Pvt Tim Hall Copyright 2010 John Wiley Sons Inc Building Proteins from Amino Acids The bond between amino acids in which the acid group of one amino acid is connected to the amine group of another amino acid Peptide bond Dipeptide 2 amino acids AA Tripeptide 3 AA Polypeptide many AA Proteins may contain 100 10 000 amino acids Building Proteins from Amino Acids Structure of proteins based in part on sequence of AA in polypeptide chain AA side chains are hydrophilic or hydrophobic Form specific shapes due to interactions between the side chains of amino acids 3 dimensional Shape is critical to protein function Copyright 2010 John Wiley Sons Inc Amino Acids and Protein Structure Amino Acids and Protein Structure Protein and denaturation Definition of denaturation Alteration of a protein s three dimensional structure Due to exposure to heat acids bases or salts ex Cooking meat or eggs and marinating meat will denature the protein Protein Digestion and Absorption Copyright 2010 John Wiley Sons Inc Figure 6 4 Terms to be familiar with for protein digestion absorption Hydrochloric acid Pepsin from pepsinogen Denaturation Protease Tripeptide Dipeptide Amino acid Transport protein Copyright 2010 John Wiley Sons Inc Absorption of amino acids requires active transport Amino acids Fig 3 11 p 77 Active transport requires energy and carrier molecule This allows amino acids to move from area of lower concentration to higher concentration Amino acids with similar structures use the same transport system Sources of amino acids for the body Copyright 2010 John Wiley Sons Inc Creation of nonessential amino acids Limiting amino acids essential amino acid available in lowest amount relative to body s need Synthesis of New Proteins DNA in the cell nucleus contains instructions for protein synthesis Gene DNA segment that codes for a specific protein Gene mutations can result in errors in protein synthesis Example sickle cell anemia Specialized RNA molecules carry out instructions for protein synthesis Synthesizing Protein Copyright 2010 John Wiley Sons Inc Synthesis of New Proteins The copy of the DNA code for protein to be synthesized This occurs in the The molecule that reads and brings the amino acid to ribosome to make protein Copyright 2010 John Wiley Sons Inc Gene regulation All cells in body contain the same DNA During development some genes are turned on others are turned off so cells can carry out specific functions Example insulin producing cells turn on the insulin gene and turn off muscle contraction genes Chemicals can turn genes on and off For example high iron turns on the ferritin gene to make more ferritin which is needed for iron storage 2012 John Wiley Sons Inc All rights reserved Protein functions Speed up chemical reactions ex enzymes Structures Some chemical signals ex hormones Transportation of substances Movement of muscles Immunity example antibodies Blood clotting Fluid balance 2012 John Wiley Sons