Nutr 2105 Ch 6 Notes
Nutr 2105 Ch 6 Notes 2105
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This 4 page Class Notes was uploaded by Veronica Fostik on Monday February 22, 2016. The Class Notes belongs to 2105 at East Carolina University taught by Kimberly Lukhard in Spring 2016. Since its upload, it has received 49 views. For similar materials see Nutrition Science in Nutrition and Food Sciences at East Carolina University.
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Date Created: 02/22/16
NUTR 2105 CH 6 Proteins Atoms: carbon, hydrogen, oxygen, nitrogen Amino acids: carbon, hydrogen, amino & acid group, side group More complex than fats or carbs 21 amino acids o each have different characteristics o essential amino acids Peptide bonds link amino acids o condensation reactions Amino acid sequencing o Amino acid sequence determines shape of polypeptide chain o Primary structure: chemical bonds o Secondary structure: electrical attractions o Tertiary structure: hydrophilic & hydrophobic o Quaternary structure: 2 or more polypeptides 4 highly folded polypeptide chains form globular hemoglobin protein Denaturation o Disruption of stability o Uncoil & lose shape o Stomach acid Protein Digestion Mouth Stomach o Hydrochloric acid denatures proteins o Pepsinogen to pepsin Small Intestine o Hydrolysis reactions o Peptidase enzymes Protein Absorption Transport into intestinal cells Unused amino acids transported to liver Enzyme digestion Predigested proteins Protein Synthesis Uniqueness or each person Amino acid sequences of proteins o Genes- DNA Want to have adequate protein in diet DNA template to make mRNA o Transcription mRNA carries code to ribosome o ribosomes are “protein factories” mRNA specifies sequence of amino acids o Translation- tRNA There can be sequencing errors Gene expression & protein synthesis o Capability of body cells o Protein needs Dietary influence on gene expression determines diseases Roles of Proteins Growth & maintenance o Building blocks for most body structures (collagen) o Replacement of dead or damaged cells Enzymes o Break down, build up, & transform substances o Catalysts o Each enzyme facilitates specific chemical reaction Hormones o “messenger molecules” o transported in blood to target tissues Regulators of fluid balance o Edema Acid-base regulators o Attract hydrogen ions Transporters Antibodies o Defend body against disease o Immunity- memory Energy & glucose o Starvation & insufficient carb intake (waste of lean body tissue) Protein Metabolism Protein turnover & amino acid pool o Continuous production & destruction o Amino acid pool is always constant Used for protein production Used for energy (if no nitrogen) Nitrogen balance o 0 nitrogen balance o positive & negative nitrogen balance Making other compounds o Neurotransmitters, melanin, thyroxin, niacin Making fat o Energy & protein exceed needs o Can cause weight gain Deaminating amino acids o No nitrogen-containing amino acid group Ammonia & keto acid o Body can transfer amino groups from an amino acid to keto acid, forming new nonessential amino acid & new keto acid Transamination needs B6 vitamin coenzyme Make proteins & nonessential amino acids o Breakdown of proteins, keto-aicds, liver cells Converting ammonia to urea o Liver- ammonia & carbon dioxide o Liver releases urea into blood o Kidneys then filter urea out of blood o Liver & kidney disease o Protein intake & urea production depends on water consumption Protein Quantity 2 factors: digestibility & amino acid composition Digestibility o Foods consumed o Animal vs plant proteins Amino acid composition o Essential amino acid consumption & nitrogen-containing amino groups Reference protein (pre-school children) High-quality proteins o Animal vs plant proteins Complementary proteins o Low-quality proteins combined to provide adequate levels of essential amino acids Protein Regulations for Food Labels Amount of protein in grams % Daily value Protein-Energy Malnutrition (PEM) Insufficient intake of protein can lead to malnutrition & low energy Children can have poor growth if malnourished Loss of muscle or excessive weight loss Marasmus (for age) o Chronic PEM o Children 6-18 months, people in poverty, skin & bones (old people) o Impaired growth, wasting of muscles, impaired brain development, lower body temp o Improper digestion & absorption Kwashiorkor o Acute PEM o Children 18 months to 2 years (develops rapidly) o Aflatoxins o Edema, fatty liver, inflammation, infections, skin & hair changes, free-radical iron, major weight loss, loss of appetite Marasmus-Kwashiorkor mix Infections are high o Degradation of antibodies to protect against o Heart failure & death Rehab o Rehydration & nutrition intervention-add protein slowly back into body Health Effects of Protein High-protein diets can cause disease o Heart disease, cancer, kidney disease, osteoporosis (calcium excretion goes up) Recommended Intakes for Protein Have an adequate amount in diet- differs for everyone 10-35% of daily intake Adults: 0.8g/kg of body weight/day Serving sizes- don’t overeat (moderation) Protein powders Muscle work vs protein supplements o Athletic performance o Whey protein (complete protein that contains all 9 essential amino acids) Promotes muscle growth & growth of lean tissue Amino acid supplements o Can be risky if take too much o Lysine & tryptophan
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