Chapter 6Objectives for Chapter 6What Are Proteins and Why Are They Important?The Structure of an Amino AcidEssential, Nonessential, and Conditional Amino AcidsThe Making of a ProteinAnimation: The Building Blocks of ProteinsPowerPoint PresentationDenaturing a ProteinDenaturation of Proteins Changes Their ShapeWhat Happens to the Protein You Eat?Digesting and Absorbing ProteinsThe Fate of Amino Acids in Your BodyAnimation: Protein DigestionAnimation: Protein AbsorptionYour Body Degrades and Synthesizes ProteinsYour Body Degrades and Synthesizes ProteinsProtein SynthesisDNA Directs Synthesis of New ProteinsHow Does Your Body Use Proteins?An Enzyme in ActionEdemaAnimation: Protein SynthesisSlide 24Proteins as Transport ChannelsSlide 26How Much Protein Do You Need?Animation: Nitrogen BalanceNitrogen Balance and ImbalanceNot All Protein Is Created EqualYou Can Determine Your Personal Protein NeedsSlide 32Slide 33Slide 34“The Blue Zones” Sardinian Diet“The Blue Zones” Sardinian DietWhat Are the Best Food Sources of Protein?What Americans Are EatingFood Sources of ProteinSlide 40Slide 41Slide 42What Happens if You Eat Too Much or Too Little Protein?Slide 44Where’s the Protein and Saturated Fat in Your Food?Eating Too Little Protein Can Lead to Poor Bone Health and MalnutritionHow Do Vegetarians Meet Protein Needs?Slide 48Potential Benefits and Risks of Vegetarian DietsSlide 50Slide 51Vegetarian Food Guide PyramidSlide 53Nutrition in the Real World: The Joy of SoyThe Joy of Soy© 2012 Pearson Education, Inc.Chapter 6Proteins and Amino Acids© 2012 Pearson Education, Inc.Nutrition and You, 2eObjectives for Chapter 6Explain how proteins are different from carbohydrates and lipids.Describe the basic structure of an amino acid.Explain the difference between essential and nonessential amino acids.Identify the key steps in digesting protein.Identify the functions of protein in the body.Identify sources of lean protein in the diet.Create a diet plan that achieves the Recommended Dietary Allowance for protein.Calculate the recommended protein intake for an individual based on the Dietary Reference Intakes.Explain the health consequences of consuming too little or too much protein.Describe the benefits and risks of a vegetarian diet.© 2012 Pearson Education, Inc.Nutrition and You, 2eWhat Are Proteins and Why Are They Important?Proteins are the predominant structural and functional materials in every cellContain carbon, hydrogen, oxygen (like carbohydrates and fats) In addition, also contain nitrogenEach amino acid has:Acid group (COOH)Amine group (NH2)Side chain (unique)All proteins consist of some combination of 20 unique amino acids© 2012 Pearson Education, Inc.Nutrition and You, 2eFigure 6.1The Structure of an Amino Acid© 2012 Pearson Education, Inc.Nutrition and You, 2eEssential, Nonessential, and Conditional Amino AcidsNine essential amino acidsCannot be made by the body It is “essential” to obtain them from the dietEleven nonessential amino acidsCan be synthesized in the body from other amino acids or by adding nitrogen to carbon-containing structuresConditionally essential amino acidsUnder certain conditions, some nonessential amino acids cannot be made in body© 2012 Pearson Education, Inc.Nutrition and You, 2eFigure 6.2The Making of a Protein© 2012 Pearson Education, Inc.Nutrition and You, 2eAnimation: The Building Blocks of Proteins© 2012 Pearson Education, Inc.Nutrition and You, 2eTable 6.1© 2012 Pearson Education, Inc.Nutrition and You, 2eFigure 6.3Denaturing a Protein© 2012 Pearson Education, Inc.Nutrition and You, 2eDenaturation of Proteins Changes Their ShapeDenaturation: the alteration (unfolding) of a protein’s shape, which changes the structure and function of the proteinExamples: cooking meat, eggs changing textureStomach acid untangles proteins to aid in digestion© 2012 Pearson Education, Inc.Nutrition and You, 2eWhat Happens to the Protein You Eat? Dietary proteins are digested and absorbed in stomach and small intestineStomach acids denature protein andActivate pepsin, which breaks down protein into shorter polypeptidesIn the small intestine, polypeptides broken down into tripeptides, dipeptides, and amino acidsAmino acids enter blood and travel to liver© 2012 Pearson Education, Inc.Nutrition and You, 2eDigesting and Absorbing Proteins Figure 6.4© 2012 Pearson Education, Inc.Nutrition and You, 2eThe Fate of Amino Acids in Your BodyFigure 6.5© 2012 Pearson Education, Inc.Nutrition and You, 2eAnimation: Protein Digestion© 2012 Pearson Education, Inc.Nutrition and You, 2eAnimation: Protein Absorption© 2012 Pearson Education, Inc.Nutrition and You, 2eYour Body Degrades and Synthesizes ProteinsAmino acids come from:DietBreakdown of proteins in the bodyA limited supply is stored in amino acid pools in blood and cells for needed protein synthesisProtein turnover: process of continuous breakdown and synthesis of protein from its amino acids© 2012 Pearson Education, Inc.Nutrition and You, 2eYour Body Degrades and Synthesizes ProteinsAmino acids can be used to make:Body proteinsNon-protein substances Examples: thyroid hormone, melaninAfter amine groups removed, converted to urea, excreted in urine, amino acids can also be:Burned for energyStored as fatMade into glucose© 2012 Pearson Education, Inc.Nutrition and You, 2eFigure 6.6Protein Synthesis© 2012 Pearson Education, Inc.Nutrition and You, 2eDNA Directs Synthesis of New ProteinsDNA in the cell nucleus contains instructions for protein synthesisGene: DNA segment that codes for specific proteinSpecialized RNA molecules carry out instructions for protein synthesisMessenger RNA (mRNA) and transfer RNA (tRNA) perform very specific roles during protein synthesisWhen abnormalities occur during protein synthesis, serious medical conditions may resultExample: sickle-cell anemia© 2012 Pearson Education, Inc.Nutrition and You, 2eHow Does Your Body Use Proteins?Proteins provide structural and mechanical support and help maintain body tissuesCollagen: a ropelike, fibrous protein that is the most abundant protein in your bodyConnective tissue: the most abundant tissue type in the body; made up primarily of collagen, it supports and connects body parts as well as provides protection and insulationProteins build most enzymes and many hormonesProteins help maintain