Chapters 6 & 7 Notes
Chapters 6 & 7 Notes HUN1201-0006
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Date Created: 10/18/15
Chapter 6 Notes What are Proteins large complex molecules found in cells of all living things 0 Synthesis controlled by our DNA 0 Contain carbon hydrogen oxygen and nitrogen 0 Made from 20 different amino acids How do Proteins differ from Starch 0 Starch is composed of glucose molecules 0 Protein is composed of amino acid chains Amino Acids 0 Nine essential amino acids Cannot be produced in sufficient quantities to meet physiological needs Must be obtained through food 0 Nonessential amino acids Can be synthesized in sufficient quantities Don t need to consume them in the diet Nonessential Amino Acids the transfer of an amine group from an essential amino acid to a different acid group and side chain R group Used to make new amino acids Conditionally essential amino acids nonessential amino acids become essential PKU tyrosine becomes a conditionally essential amino acid that must be provided in the diet How are Proteins Made 0 Proteins are long chains of amino acids 0 Amino acids are connected by peptide bonds process by which cells use genes to make proteins segment of DNA that serves as a template for the synthesis of a particular protein messenger RNA copies the genetic info from DNA genetic info in RNA is converted into the amino acid sequence of a protein existing proteins are degraded to provide the building blocks for new proteins Amino acid pool includes amino acids from food and cellular breakdown 0 Protein organization determines function Sequential order of the amino acids Spiral shape from twist in the amino acid chain proteins uncoil and lose their shape Damaging substances heat base heavy metal alcohol Protein function is ost Denatured enzyme High fever Blood pH out of normal range During digestion Protein in the Diet Protein synthesis all essential amino acids must be available to the cell essential amino acid that is missing or in the smallest supply slows downhaults protein synthesis insufficient essential amino acids Inadequate energy consumption limits protein synthesis sufficient amounts of all nine essential amino acids Derived from animal and soy protein Soy protein sufficient for adults not infants combine two or more complete protein sources to make complete protein two or more foods are combined to supply all nine essential amino acids for a complete protein Protein Digestion Protein digestion begin in the stomach Hydrochloric acid denatures protein strands and activates pepsin enzyme breaks down proteins into short polypeptides and amino acids hormone controls hydrochloric acid production and pepsin release Digestion continues in the small intestine Pancreatic enzymes proteases complete protein digestion Special sites small intestines transport amino acids dipeptides tripeptides High doses of individual amino acid supplements can lead to amino acid toxicity and deficiencies Protein Quality Methods for estimating protein quality chemical score protein digestibility corrected amino acid score 0 animal protein and many soy products are highly digestible Functions of Proteins 0 cell growthrepairmaintenance o enzymes and hormones o fluid and electrolyte balance 0 acid base balance 0 immune system 0 energy source 0 nutrient transportstorage Protein Adequacy o nitrogen balance determines protein needs positive nitrogen balance negative nitrogen balance in nitrogen balance RDA For Protein 0 8 g per kg body weight per day 0 Recommended of energy is 1035 of total energy intake 0 Protein needs are higher during growth and development children adolescents and pregnantlactating women Too Much Protein can be Harmful 0 High cholesterol and heart disease Animal proteinrich diets are associated with high blood cholesterol levels saturated fat 0 Contribution to bone loss High protein diets increase calcium excretion and possibly lead to bone loss Adequate protein intake associated with decreased risk of osteoporosis o Kidney Disease High protein diets associated with an increased risk among susceptible individuals People with diabetes have higher rates of kidney disease and may benefit from a low protein diet Max of2 g of protein per kg of body weight each day Protein Sources 0 Meats 0 Dairy 0 Soy products 0 Whole grains 0 Legumes 0 Nuts 0 Quorn Vegetarian Diets restricting the diet to foods of plant origin 0 People choose vegetarianism for Health benefits Ecological reasons Religious reasons Ethical Concerns over food safety Health Benefits of Vegetarianism 0 Lower fattotal energy intake 0 Lower blood pressure 0 Reduced risk of heart disease 0 Fewer digestive problems 0 Reduced risk of some cancers 0 Reduced risk of kidney disease kidney stones and gallstones Challenges of Vegetarian Diets 0 Can be low in some nutrients 0 Associated with disordered eating 0 Varied and adequate diet planning 0 Soy and complementary proteins 0 Vegetarian food guide pyramid 0 Special attention to vitamins D 312 riboflavin minerals zinc and iron Proteinenergy Malnutrition caused by inadequate protein and energy intake 0 Common forms Maramus and Kwashioror grossly inadequate energy and nutrient intake 0 Consequences Wasting and weakening of muscles Stunted brain development and learning Depressed metabolism Stunted physical growth Deterioration of the intestinal lining Severely weakened immune system Fluid and electrolyte imbalances disease resulting from low protein intake 0 Symptoms Some weight lossmuscle wasting Retarded growth and development Edema resulting from distention of the belly Fatty degeneration of the liver Loss of appetite sadness irritability apathy Skin problems and hair loss Genetic Disorders 0 Numerous disorders are caused by defective DNA inherited cannot breakdown phenylalanine o Phenylalanine and metabolic byproducts build up in tissues and can cause brain damage 0 Should consume low amounts of phenylalanine inherited disorder of the red blood cell 0 Inherit the gene from both parents 0 Cells become crescent shaped which makes them hard and sticky 0 Restricted blood flow damages organs 0 Sickled cells have a shorter life span 0 Symptoms impaired vision convulsions headaches bone degeneration inherited affects the respiratory system and digestive tract 0 Alteration of chloride transport in cells 0 Cells secrete a thick sticky mucus 0 Symptoms coughing wheezing and stunted growth Chapter 7 Notes the sum of all chemical amp physical processes by which the body breaks down and builds up molecules Calorimeter measures a food s energy content process of making larger chemically complex molecules from smaller ones Critical for growth repair maintenance and synthesis of chemical products essential for human functioning Requires energy breakdown of larger complex molecules to smaller basic ones Begins with digestion chemical reactions breakdown proteins lipids amp carbs Old cells are broken down for repair or replacement Releases energy an organic compound used by cells as a source of energy Potential energy is stored in the bonds between the phosphate groups When bonds are broken energy is released This energy is used to keep cells functioning The mitochondria is the primary site for production Condensation amp Hydrolysis anabolic process simple units combine to form a larger more complex molecule Water is released as a byproduct usually a catabolic process large molecule is broken apart with the addition of water addition of a phosphate group to a compound When the high energy phosphate bonds in ATP are broken energy is released and phosphate is transferred to other molecules When glucose is phosphorylated it can be oxidized foe energy or stored as glycogen OxidationReduction Reactions Molecules exchange electrons hydrogen Exchange reactions occur together Molecule donating an electron becomes oxidized ts electron is removed by oxygen Molecule acquiring an electron is reduced n gaining an electron it becomes more negatively charged Metabolic Pathways clusters of chemical reactions that occur sequentially to achieve a particular goal Occur in a specific part of the cell My be limited to specific organstissues Metabolic Enzymes o Enzymes mediate chemical reactions 0 Coenzymes are nonprotein substances necessary for enzyme activity 0 Cofactors are typically minerals required for enzyme activity Iron magnesium and zinc function as cofactors Energy from Carbs 0 When glucose is transported to the liver it is Phosphorylated and metabolized for energy or stored as glycogen Released into circulation for other cells to use as fuel or stored as glycogen muscle tissue Converted to fatty acids if glucose exceeds energy needs and stored as triglycerides in adipose tissues 0 Fructose and galactose are converted to glucose in the liver and follow the same process anaerobic reaction occurs in the cytosol Energy from Fat dietary and adipose triglycerides are broken down by lipases to yield glycerol and three free fatty acids converted to pyruvate then to acetyl CoA for entry to the TCA cycle 0 Fatty acids are used for energy BetaOxidation of Fatty Acids 0 Attached to albumin fatty acids are transported to working cells in need of energy muscleliver cells 0 Fatty acids must be activated by coenzyme A before being shuttled across the mitochondrial membrane by carnitine o 16 carbon fatty acids are broken down into 2 carbon segments to form acetyl CoA Fatty Acids cannot form Glucose 0 There is no membrane pathway to convert acetyl CoA into pyruvate 0 Cells cannot convert fatty acids to glucose Ketone Synthesis byproduct of fat catabolism occurs when ketones acidic inappropriately lower blood pH occurs when blood pH falls further resulting in severe dehydration Energy from Protein o The body preferentially uses fat and carbs as fuel sources 0 Protein is saved for metabolic functions that can t be performed by other compounds 0 Protein is used for fuel primarily when total energy or carb intake is low dietary proteins are digested into amino acids or small peptides 0 Amino acids are transported by the liver made into protein and released into the bloodstream for uptake by other cells for building and repair function 0 Excess dietary protein is used or stored as triglycerides 0 During starvation the body turns to its own tissues for energy Stored Energy 0 Stored energy can be used during times rest fasting or exercise 0 Extra energy is stored as carbs in limited quantities and fat in unlimited quantities Synthesizing Macronutrients making the new glucose from nonglucose substrates 0 Maintains blood glucose during sleep fasting trauma and exercise 0 Protein catabolism for glucose production can draw on vital tissue proteins de novo synthesis making fat from nonfat substances 0 Mostly occurs in liver cells 0 Amino acid synthesis The body makes the carbon skeleton for nonessential amino acids Amine group comes from transamination Synthesis of NEAA occurs only when the body has had enough energy and nitrogen Hormones Regulates Metabolism o Insulin is the primary anabolic hormone Increases in the blood a meal Activates storage enzymes 0 Glucagon epinephrine and cortisol are catabolic hormones Metabolic Responses to Feeding bloodstream enriched with glucose fatty acids and amino acids Glucose stored as glycogen Glycogen stores are saturated remaining glucose is stored as triglycerides Fatty acids are stored as triglycerides mostly in adipose tissues Carbon skeletons are converted to fatty acids for storage as triglycerides Metabolic Responses to Fasting 0 liver glycogen is broken down blood glucose is released 0 most cells can switch to using fatty acids as fuel to conserve glucose for brain and other cells that rely on glucose as fuel 0 ketones form as acetyl CoA units are blocked from entering the TCA cycle Metabolic Responses To Starvation 0 Body shifts to survival mode 0 Blood glucose is maintained 0 Decline in activity body temp and metabolic rate 0 Fatty acids become the primary source of fuel 0 Muscle protein supplies glucose