Protein: Amino AcidsObjectivesSlide 3ProteinAmino AcidsSlide 6Slide 7ProteinsSlide 9Slide 10Slide 11Slide 12Protein DigestionSlide 14Slide 15Protein AbsorptionProtein SynthesisSlide 18Slide 19Roles of ProteinsSlide 21Slide 22Slide 23Slide 24Slide 25Slide 26Protein MetabolismSlide 28Slide 29Protein QualitySlide 31Slide 32Food LabelsNitrogen BalanceProtein-Energy Malnutrition (PEM)Slide 36Slide 37Slide 38Health EffectsSlide 40Recommended IntakesSlide 42Slide 43Slide 44Slide 45Protein: Amino AcidsObjectives•After reading Chapter 5, class discussion and activities you will be able to:–Describe the role of proteins–Distinguish between complete and incomplete proteins–Identify sources of quality protein –Calculate calories from proteinObjectives•Describe protein digestion/absorption•Identify RDA for protein•Discuss health related effects of proteinProtein•Essential part of all living cells•Found in animals and plants; Particularly rich in animal foods – meats, poultry, eggs, etc.•Protein is in your skin, hair, nails, muscles, etc.•Made of amino acids – amino acids contain nitrogen, which is necessary for life.Amino Acidsp. 182Fig 6-1Amino Acids•Nonessential amino acids–Body can synthesize–Over half of the 20 AA•Essential amino acids–Body cannot synthesize–Nine (9) •Conditionally essential amino acids–PhenylalanineTyrosine; New Bornsp.182 Tab 6-1Proteins•Peptide bond–Dipeptide–Tripeptide–PolypeptideProteins•DipeptideProteins•Polypeptide (Example: Insulin)•Protein shape and function•Amino Acid SequencesProteins•Protein denaturation–Uncoiling & loss of shape–Therefore, loss of function–Caused by heat, acid, mechanical–Examples: cooked egg, egg whites, curdling of milk, separation of foods with milk or egg (syneresis)Protein Digestion•Mouth–Mixing, moisturizing•Stomach–HCl–Pepsinogen  pepsin•ProenzymeEnzymeProtein Digestion•Small intestine–Proteases•Intestinal and pancreatic–Peptidasesp. 186Fig 6-6Protein Absorption•Carriers–Transport AA into intestinal cells–Used for synthesis and energy•Capillaries–Carried to liver•Absorption misconceptions–Enzyme/amino acid supplementsProtein Synthesis•Delivering the instructions –DNA•mRNA- attaches to ribosome–Protein-making machineProtein Synthesis•Sequencing errorsRoles of Proteins•Building material: Building blocks of muscles, blood, skin, bones, teeth; protein matrix=collagen –Growth–MaintenanceRoles of Proteins•Enzymes=catalystsp. 190 Fig 6-9Roles of Proteins•Hormones–Switching MachinesRoles of Proteins•Regulation of fluid balance–Edema•Acid-base regulation–Acidosis–Alkalosis•Transport proteinsRoles of Proteins•Immunity: Molecular Memory–Antibodies: Giant protein molecules designed to combat–Antigens: Invading foreign proteins (virus)Roles of Proteins•Source of energy–Gluconeogenesis–No storage source=muscle wasting–“Amino acid pool”•Other roles–Fibrinblood clotting–Opsin—light-sensitive pigmentProtein Metabolism•Protein turnover–Amino acid pool: supply of AA from food/body; collect in cells & blood; ready for use•Nitrogen balance–Positive nitrogen balance–Negative nitrogen balanceProtein Metabolism•Using amino acids to make proteins=CONDENSATION•Using amino acids to make nonessential amino acidsProtein Metabolism•Using amino acids to make other compounds–Neurotransmitters•Using amino acids for energy and glucose•Deamination: AA stripped of N–Ammonia producedProtein Quality•High-quality proteins–All essential AA–Animal proteins=complete–Plant proteins=incomplete•Amino acid composition–Limiting amino acid•Digestibility–Animal vs. vegetableProtein Quality•PDCAAS–Protein digestibility-corrected amino acid score•Reference ProteinProtein Quality•Complementary proteins–Two protein foods make up for the lack of certain amino acids in each other when eaten togetherFood Labels•Quantity of protein•Daily Value–50 g protein•10% of a 2000 kcal dietNitrogen Balance•Determine adequacy of protein intake•N2 In - N2 Out = Nitrogen Balance–N2 In = Protein Intake as Nitrogen–N2 Out = 24 Hour Urine Collection for N2 + Stool, Insensible Losses•Positive Nitrogen Balance–Body excretes less protein than is taken in (Anabolism)•Negative Nitrogen Balance–Body excretes more protein than is taken in (Catabolism)Protein-Energy Malnutrition (PEM)•Marasmus–Slow developing, chronic PEM–Muscle wasting; no body fat–Pluckable hair; dry skin•Kwashiorkor ??????•Marasmus-kwashiorkor mixp. 197Tab 6-3p. 197 Tab 6-3Protein-Energy Malnutrition (PEM)•Infections not protein intake–Dysentery•C-Reactive ProteinHealth Effects•Conditions Associated with Other Nutrients:–Osteoporosis – Calcium–Heart Disease – Fat–Obesity – Fat/CHO–Cancer - FatHealth Effects•Genetic Associated Diseases–Phenylketonuria–Sickle Cell Anemia•Kidney DiseaseRecommended Intakes•RDA–0.8 g/kg/day–10% - 35% of energy intakeObjectives•After reading Chapter 5, class discussion and activities you will be able to:–Describe the role of proteins–Distinguish between complete and incomplete proteins–Identify sources of quality protein –Calculate calories from proteinObjectives•Describe protein digestion/absorption•Identify RDA for protein•Discuss health related effects of