EXSS 276 1st Edition Lecture 6 Outline of Last Lecture I. Carbohydrate Metabolism Regulation: HormonesII. SummaryOutline of Current LectureI. LipidsII. TerminologyIII. Lipid Metabolism: Basic StepsIV. Lipid Metabolism Regulation: Substrates and ProductsV. Lipolysis – LipogenesisVI. Ketone BodiesVII. Protein MetabolismCurrent LectureI. Lipidsa. Lipid = fatb. Triglycerides (glycerol and 3 fatty acids)i. How we store fat in our bodyc. Phospholipids - membranesd. Steroidsi. Lipids that contain rings of carbon normally make up steroid hormones e. Fatty acids = long carbon chainsf. Fat soluble vitamins (A, D, E, K)g. Lipoprotein i. Low density (LDL) – turns into plaqueii. High density (HDL) – more protein content, more productive h. Monoglyceride = glycerol and 1 fatty acidi. Triglyceride = glycerol and 3 fatty acidsj. One link = saturated (single bonds to hydrogen everywherek. Fatty acid chain that is bent – double bond (eliminated hydrogens) = unsaturatedi. Mono-unsaturated = one double bondii. Poly-unsaturated = more than one double bondThese 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.iii.II. Terminologya. Lipogenesis: formation of lipidb. Lipolysis: breakdown of lipidc. Beta-oxidation: mitochondrial process, converts fatty acid to Acetyl CoA III. Lipid Metabolism: Basic Stepsa. Conversion of stored triglycerides to Acetyl CoAi. Lipolysis: breakdown triglyceride into glycerol and fatty acid component1. Catalyzed by lipases, regulated by hormones2.ii. Glycerol converted to glyceraldehyde-3-phosphate1. Converted to glucose/pyruvate depending on demands of bodyiii. Fatty acids converted to Acetyl CoA1. Beta-oxidation: enzyme breaks off 2 carbons at a time2. Co enzyme A plus 2 C’s from fatty acid chain gives Acetyl CoA3.b. Acetyl CoA enters Krebs cyclei. Products: 3 NADH, FADH2, 2 CO2, ATPii. 1 triglyceride (18 C fatty acid chain) = 129 ATP (lipid metabolism provides much more energy)c. NADH and H+ and FADH2 enter ETCIV. Lipid Metabolism Regulation: Substrates and Productsa. Characteristicsi. Slow rate of ATP productionii. High yield of ATP productioniii. Oxygen dependent (extremely)b. Regulationi. Inhibit/decrease rate of beta oxidation1. Increased Acetyl CoA or NADH + H+a. Negative feedback loop: don’t want to make up more Acetyl CoA – will not break down more lipids 2. Increased lactate; H+ ion production a. H+ = acidicii. Stimulate/increase rate1. Increased oxygen availabilityV. Lipolysis – Lipogenesisa.b. Conversion in both directions*c. Control of lipolysis:i. Increase rate: catecholamines, cortisol, thyroid hormones, growth hormone and IGFsii. Decrease rate: insulind. Control of Lipogenesis:i. Increase rate: insulinVI. Ketone Bodiesa. Result of lipid catabolismb. Two acetyl CoA molecules combine to form acetoacetic acid which is converted to beta-hydroxybutyric acid and acetonec. Heart muscle and kidney cortex prefer to use acetoacetic acid for ATP productiond. *Very acidic – high levels of acid can damage functionality of a cell so do not want build up e. Can enter bloodstreamf. Applicationi. Blood ketone levels are usually very low1. Many tissues use ketones for ATP productionii. Fasting, starving, high fat/low carb diets result in excessive beta oxidation and ketone productioniii. Acidosis (ketoacidosis) = abnormally low blood pH; body is unable to adequately buffer acids1. Sweet smell of ketone body acetone on breath2. Occurs in diabetics experiencing serious insulin deficiencya. Triglycerides used for ATP production instead of glucoseb. Lack of insulin accelerates rate of lipolysis 3. Side effects: depression, damages nervous system, disorientation, comaVII. Protein Metabolisma. Protein conformationi. Proteins are made of amino acids (20,000 – 25,000 different combinations)ii. Three main groups attached1. Amino (NH2)2. Acidic carboxyl group (COOH)3. Side chain (R group) b. Essential vs. Non-essential Amino Acidsi. Essential-have to introduce them into our body (must eat them)ii. Can cause diseases-sickle cell anemia1. Valine is substituted in DNAc. Organization of Proteinsi. Primary structure1. Amino acid sequence2. Polypeptide chain: many amino acids that build up3.ii. Secondary structure1. Twisting and folding of neighboring amino acids, stabilized by hydrogen bondsiii. Tertiary structure1. 3-D shape of polypeptide