NTR 306 Exam #3 Notes.docx

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NTR 306
Deanna Staskel

NTR 306 Learning Objectives: Exam 3 Chapter 7 – Metabolism: Transformations and Interactions 1. What is ATP and how is it used by the body?  Adenosine triphosphate  “Energy currency for our cells”; High Energy molecule: adenine, ribose + 3 phosphate groups; must continually recharge ATP to provide constant E  ATP attaches a phosphate group to an enzyme, for example, to do work  Anabolic vs. Catabolic Rxns: oAnabolic  Use ATP to combine smaller molecules (glucose) into larger compounds (glycogen) and release small amounts of heat oCatabolic  Break down large molecules – Release E in form of ATP and heat  ATP production occurs in mitochondria 2. Describe how carbohydrates, proteins, and fats are used to meet the energy needs of the body.  Carbs = poly/monosaccharides; sugar o4kcal/grams obrain + blood cells; quick ATP (ATP production = aerobically an anerobically) = glucose! omost important macronutrient for E  Proteins = polypeptides, amino acids o4kcal/grams ogoes into first 3 stages (glycolysis, acetyl CoA, TCA Cycle) oproduces ketones when you are fasting (& aren‟t producing or consuming enough glucose)  Fats = triglycerides, 3 FA (made into fat) + glycerol backbone (made into sugar) o9kcal/grams ogoes into first 2 stages (acetyl CoA, glycolysis)  Alcohol = 7kcal/grams 3. Discuss the TCA cycle and the electron transport chain.  …in book and on slides 4. Explain what happens in the body during short & long-term and fasting (what compounds the body uses to keep blood sugar levels within normal limits & produce ATP).  Fasted/limited carbohydrate intake for 3 days – ketogenesis reaches peak levels oKetone bodies from FA used as alternative fuel source oAcetyl CoA great supply b/c it is not being metabolized in TCA due to shortage of oxaloacetate  Ketone bodies are formed from acetyl CoA oBrain uses ketone bodies for fuel when stores are low to reduce consumption of blood glucose  Ketogensis is normal response to fasting; but has consequences a. Ketoacidosis, type 1 diabetes, result from build-up of excess ketone bodies in blood b. Can cause impaired heart function, coma, death  Inadequate Energy NTR 306 Learning Objectives: Exam 3 oProtein meets some glucose needs oShift to ketosis: ketones produced when glucose not available oKetosis causes suppression of appetite oSlowing of metabolism  Produce ATP? oStored E provides ATP to take care of E needs  1 – blood gluose levels maintained through use of glycogenolysis  Lipolysis provides FA for E, reducing use of glucose by cell oAfter liver glycogen has been depleted, gluconeogenesis initiated  Using AA, glycerol, pyruvate, lactate oKetone bodied, from FA, used if fasting occurs 5. What are Ketones? Why are they created? What are they created from?  Incomplete breakdown of fat when glucose is not available in the cells oCombination of acetyl CoA fragments derived from FA oProvide fuel for brain cells oReplace carbohydrates; made of AA and FA  How are they made? oCondensation of 2 molecules of acetyl CoA and removal of the CoA forms acetoacetate or a ketone body  Use protein if no glucose – break down ketones oIf we didn‟t breakdown protein (ketones) we would breakdown muscle tissue, brain tissue, organs  Why ketones are produced: oIf body continues to use protein from diet (& breaking down body protein) - form ketones which are an alternative fuel source for the brain (replace glucose).  Ketones indicate that you are in starvation mode  Those who rely on ketones suffer from memory loss  Ketogenic vs. Glucogenic AA oKetogenic AA = cannot be converted to glucose (FA)  Leucine  Lysine oKetogenic and Glucogenic AA  Isoleucine  Tryptophan  Phenylalanine  Tyrosine oGlucogenic AA  14 other AA 6. Explain what happens in the body during feasting (what the body does with „extra‟ energy nutrients).  E-yielding nutrients are broken down to monosaccharides, fatty acids (FA), glycerol, and amino acids (AA)  Excess Protein oReplaces normal daily losses, glycogen stores must be full as well NTR 306 Learning Objectives: Exam 3 oProtein oxidation uses some protein excess, but it displaces fat in fuel mix oAmino acids are deaminated – lipogenesis occurs oRemaining Carbons used to make FA – which are stored as triglycerides in adipose tissue  Excess Carbohydrate oStoring it is as glycogen (in muscle and liver) oGlycogen storage limited/filled quickly oGlucose oxidation rapidly adjusts to dietary intake of carbohydrate oGlucose converted into fat (triglycerides for storage in adipose tissue – lipogenesis) directly once glycogen stores are full  E expensive, only a little, if any, fat is made from carbohydrate oExcess carbohydrates displace fat in fuel mix  Contributes to obesity/maintenance of overweight body o25% burned when converting excess glucose to body fat o100 excess glucose calories= 75 end up as fat storage  Excess Fat oDoes not promote fat oxidation oMoves efficiently into body‟s fat stores; almost all excess stored oRequires 5% E to convert dietary fat into body fat oSo 100 excess fat calories – 95 end up as fat storage NTR 306 Learning Objectives: Exam 3 Sampling of Key Terms:  Proteolysis: the breakdown of proteins (from body tissue) into amino acids  Glycogenolysis: breakdown of glycogen in liver => glucose  Lipolysis: the enzymatic breakdown of triglycerides (from adipose tissue) into glycerol & fatty acids by hormone-sensitive lipase; lipoprotein lipase stores fat  Lipogenesis: Acetyl CoA converting into FA chains, attached to glycerol backbone to make triglyceride for storage  Gluconeogenesis: creation of new glucose from non-glucose sources (from AA, glycerol backbone)  Glycogenesis: creation of glycogen from glucose for storage  ATP/ADP  Glycolysis: breakdown of glucose o First step in formatting ATP from glucose o Takes place in cytosol/plasm of the cell o Ten-step process (BOOK!!) o 1 6-molecule glucose process to 2 3C Pyruvate; Net: 2 ATP, 2 H ions (for ETC)  Pyruvate: an intermediate formed during the metabolism of carbohydrates (no 2 required) o 2 pyruvate are transported into mitochondria w/ oxygen o Pyruvate remains in cytoplasm & converted into lactate w/o oxygen  Released into blood and taken to liver  Lactate converted to glucose – then undergoes glycolysis to pyruvate again (Cori Cycle) o Transformed into acetyl-coenzyme A (aceteyl CoA) o 2 Pyruvate + 2 coenzyme A + 2NAD+ -> 2 acetyl-CoA +2CO2 + 2 NADH  Acetyl CoA o Common product of carbohydrate, lipid, and protein & alcohol metabolism o It consists of an acetyl group attached to a coenzyme A molecule o “gateway” molecule for aerobic metabolism o Can form ketones if glucose supply inadequate  Fatty Acid Oxidation o Series of chemical rxns that breaks down FA to molecules of acetyl CoA  Chains of C need to be converted to acetyl CoA; Every 2 C‟s make 1 Acetyl CoA o FA is taken apart 2 C fragments at a time; H and e- to ETC o Each 2 C pairs are joined by other CoA and converted to Acetyl-CoA Learning Objectives: Exam 3 NTR 306 o The Acetyl CoA can then enter the TCA cycle to produce E  Ketogenesis: creation of ketone  Mitochondria – aerobic E production o More we exercise – the more we increase the amount of mitochondria in our muscle cells. Can be burning more calories. o “powerhouse of cell” o All cells – except red blood cells (lose as they mature) o Some have more than others, making some more metabolically active than others  Liver and heart cells have a lot  Coenzymes: organic molecules that function as enzyme helpers o NAD +, FAD, ATP, coenzyme A) o Help E production channels to happen – B viatmins o Assist by accepting & donating H ions, electorons & other molecules during reactions  NAD+  Derived from B vitamins: niacin (B3)  Reduced to NADH (accepts 1 H atom)  FAD  Derived from B vitamins: riboflavin (B2) “f-flavin”  Reduced to FADH (accepts 2 H atoms) 2  Coenzyme A  Large molecule that contains a molecule of ADP with two side chain groups stemming from its phosphate arms  Cori cycle o Pyruvate to lactate (and then back to glucose) o Pyruvate reduces to lactate to prevent hydrogen ions from building up in the cell o During strenuous exercise, lactate is not produced fast enough to keep up w/ hydrogen ion production  Buildup of H ions – reduces pH in cell = burning sensation in muscles after exercise o The pathway in which glucose is metabolized to lactate (anaerobic glycolysis) in the muscle, lactate is converted back to glucose in the liver, then the glucose is returned to the muscle  Anaerobic  Aerobic  Cofactors: inorganic components of an enzyme needed for the enzyme‟s activity o Often a mineral o Must be attached (bound) to the enzyme‟s active site Learning Objectives: Exam 3 NTR 306 Chapter 8: Energy Balance & Body Composition Chapters 9: Weight Management: Overweight, Obesity, & Underweight Chapter 10-highlight: Eating Disorders 1. Discuss the factors that regulate food intake and satiety (including the effects of Peptide YY, Neuropeptide Y, insulin, macronutrient content.)  Satiety: determines frequency of meals; inhibits eating until the next meal o Hunger and satiety: controlled by hormones that are produced by brain and GI tract o Triggered in ventromedial nucleus  Satiation: satisfaction after eating- how much food is consumed during a meal; stop eating  Hypothalamus: brain center that controls activities such as maintenance of water balance, regulation of body temperature, control of appetite a. Lateral hypothalamus controls hunger (ghrelin, neuropeptide Y)  Appetite: desire to eat food whether or not there is a physical hunger; may be triggered by factors such as time of day, social occasions, emotions, sight/smell of food  Factors that regulate food intake and satiety – o Peptide YY  & cholecystokinin send feedback to hypothalamus to increase satiety and decrease hunger o Neuropeptide Y  Causes carbohydrate cravings, initiates eating, decreases energy expenditure, increases fat storage.  Produced in hypothalamus – activated by ghrelin – stimulates hunger o Macronutrient content triggers insulin release – decreases hunger o Protein – promotes satiety and reduces food intake 2. Explain the components of E Expenditure: basal metabolic rate and the factors that affect it, physical activities, thermic Effect of Food (TEF)  Basal Metabolic o Energy needed to maintain life when a body is at complete digestive, physical, and emotional rest (basic processes of life) o 2/3rds of E the average person expends in a day o Activities such as: lungs inhaling/exhaling, bone marrow making new red blood cells, heart beating 100,000 times a day, kidneys filtering wastes  Basal Metabolic Rate: (calories body needs to run on) o Rate which body expends energy for these life-sustaining activities o Kcalories per kilogram body weight per hour o Slo
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