NUTR 470 1st EditionFinal Exam Study Guide • Introduction – Energy Metabolism• Energy is generated from food.• The reducing equivalents (2H) are collected by the respiratory chain for oxidation and coupled generation of ATP.• Energy balance (homeostasis)• Energy (food) intake• Energy expenditure• Malnutrition or undernutrition• Imbalance of energy• Over-nutritionBasal metabolic rate (BMR)Energy expenditure by the body when at rest, but not asleep, under uncontrolled conditions of thermal neutrality, measured about 12 h after the last meal.respiratory Quotient (RQ)—the ratio of the production of CO2 to the consumption of O2 .0.7-1.0 RQ of lipids (1g)0.7-1.0More CHO, lower end has less energy from CHOOn RQ graph, all data points lies between what two numbers? Higher end indicates what?Reducing equivalents are collected by respiratory chain for oxidation and coupled generation of ATP.Overnutrition (Obesity)Positive energy balance between intake and expenditure is the major risk factor of insulin resistance. is highly associated with type 2 diabetes and causes and exacerbates many health problems.AIs: Adequate IntakesLevels of nutrient intake judged based on less conclusive scientific information than are the RDAs.• RDAs: Recommended Dietary Allowances• Levels of essential nutrient intake judged to be adequate to meet the known nutrient needs.• RDA of carbohydrate is 130 g/day, which is lowand based on the amount of glucose needed by the brain.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Glycemic Indexa measure of the extent to which carbohydrate and carbohydrate-containing foods increase glucose levels.• Recommendations for Carbohydrates• The extent to which blood glucose is raised by a 50-g portion of a carbohydrate-containing food compared to 50 g of glucose. • Diets providing low glycemic index carbohydrates can improve blood glucose control in people with diabetes, as well as reduce elevated levels of blood cholesterol and triglycerides; have many benefits.• High fiber diets reduce the rates of glucose absorption and may help prevent cardiovascular• diseases.• Low carbohydrate and/or high fiber diets are considered as healthy foods• High fiber diets may reduce the risk of colon cancer.Digestionis the process by which food is converted into substances that can be absorbed and assimilated by the body.• Digestion of Carbohydrates• Maltase— dividing maltose into glucose + glucose• Sucrase— dividing sucrose into glucose + fructose• Lactase— dividing lactose into glucose + galactose• Final digestion products of carbohydrates are glucose, galactose, and fructose.• Endogenous Glucose Production• Why only the liver and the kidney, but not other organs, generate glucose?• Gluconeogenesis, Glycogen breakdown —> G-6-P• Glucose-6-phosphatase is the only enzyme that hydrolyzes glucose-6-phosphate to produce glucose.• Glucose-6-phosphatase is only present in the liver, kidney, and small intestine(?).Absorptionis the process by which molecules are transported through the GI epithelial cells to enter blood and lymph.SGLT 1How Glucose is absorbed by active Na+-coupled glucose transporter 1 and Galactose is also actively transported.GLUT 5How Fructose is absorbed by a facilitated diffusion systemLactose-induced diarrhea or lactose intolerance is due to a genetically deficiency of ______ in the brush- border of the duodeno-jejunal enterocytes lactase Glucoseis the only energy source for red blood cells. (For mitochondria for fatty acids)Uptake of Glucosethe first step after which glucose can be used as energy. Usually couples glucose phosphorylation--> generation of glucose-6-phosphate. Is a regulatory step in certain types of cells. May be crucial for maintaining whole body glucose homeostasis (By muscle makes a major contribution to glucose homeostasis, by tissues other than muscle may have limited roles in regulating glucose homeostasis)• Significance of Glucose Transporters• GLUT2— allows rapid uptake or release of glucose liver cells and pancreatic β cells• GLUT4 is insulin-sensitive• The response of GLUT4 to insulin is crucial for the maintenance of glucose homeostasis. • GlucoseGLUT 2In liver and pancreatic β cellsallows rapid uptake or release of glucose by liver and pancreatic β cellsGLUT 4In muscle and adipose tissue.is insulin-sensitive.The response to insulin is crucial for maintaining glucose homeostasisKmis the substrate concentration at which v is half the maximal velocity (V max/2) of the enzyme.indicates the ability of an enzyme in binding a substrate. --> when decreases, enzyme binding increases• Glycolytic Pathway • HK/GK: hexokinase/glucokinase• HK/GK catalyze the phosphorylation of glucose as the first step of glycolysis• 6PFK1 catalyzes the rate-limiting step of glycolysis• F-2,6-P2 is the most powerful activator of• ATP is generated at two steps of glycolysis• 6PFK1: 6-phosphofructo-1-kinaseHexokinase 2In nearly all cells, works with GLUT 4Has smaller KM, so easier to have reaction.glucokinase/ hexokinase 4In liver cells and pancreatic beta cells. Work with GLUT 2Has a high Vmax, fast reaction.is he determinant of glucose phosphorylation.Glycolysisis the simplest glucose metabolic flux.is crucial for the regulation of glucose homeostasis.provides immediate energyis associated with many biological functionshexokinase/glucokinasecatalyze the phosphorylation of glucose as the first step of glycolysis 6-phosphofructo-1-kinasecatalyzes the rate-limiting step of glycolysis (to generate frucose-1,6-phosphate)F-2,6-P2 (Fructose-2,6-Bisphosphate)is the most powerful activator of 6PFK1• Gluconeogenesis• Gluconeogenesis (GNG) is the biosynthesis of new glucose.• FBPase catalyzes the rate-limiting step of GNG.• FBPase F-2,6-P2 is the most powerful inhibitor of FBPase.• GNG is the generation of GLUCOSE whereas G6Pgenesis is the generation of G6P.• Cooperative Regulation in the Liver• Hepatic 6PFK2/FBP2 exemplifies how fasting/feeding regulates fuel metabolism at the molecular level• Coordination in Glycogenolysis and Glycogenesis• When glucose levels are high— Promoting glucose storage • When glucose levels are low— Promoting glucose production from the liver• Glycogenesis and glycolysis is regulated in a coordinate pattern— Rapid regulation of glucose