Metabolism I Final Exam Chapters in Review Louisa Scibelli Mitochondrion is the site of majority of metabolic energy produced in cells Chapter 2 The Cell o ATP ETC Nucleus is the largest organelle it initiates and regulates most cellular activities o Nucleic acids DNA and RNA Made from nucleotides C G A U T Protein synthesis o Cell replication DNA replicates itself o Cell transcription mRNA copies the genetic information from DNA o Cell translation genetic information in RNA is converted into the AA sequence of a protein Apoptosis is the programmed death of a cell Chapter 3 The Gastrointestinal Tract Digestion and Absorption Functions make nutrients available to cell elimination of wastes protect body from harmful substances metabolic processes Oral cavity o Saliva Esophagus Stomach Salivary amylase hydrolyzes 1 4 linkages of amylose Lysozymes kill bacteria o Movement of food via peristalsis o Lower esophageal sphincter relaxes to let food into stomach o Absorbs alcohol and aspirin o Digestion Lipids limited hydrolysis via lingual lipase and gastric lipase Proteins some hydrolysis of small polypeptides via pepsin Pepsinogen a zymogen is secreted by chief cells in response to acetocholine o Pepsinogen is activated by HCl secreted by parietal cells and pepsin autocatalytic HCl regulation o Gastrin gastrin releasing peptide GRP in response to acetylcholine Louisa Scibelli o Acetylcholine NT released by vagus nerve Can act on o Histamine produced by mast cells Release by vagus parietal cells nerve and gastrin o Somatostatin inhibits HCl release Ach inhibits secretion of somatostatin H promotes secretion GERD Gastro Esophageal Reflux Disease reflux of digestive juices from stomach into esophagus Pyloric sphincter regulates movement of food and acid from stomach to small intestine Small intestine o Digestion In the lumen CH2O hydrolysis of starch via pancreatic amylase hydrolyzes 1 6 linkages Protein pancreatic proteases are released and activated o Trypsinogen zymogen trypsin autocatalytic via Lipid hydrolysis of TAG s to MAG s FFA and glycerol via enteropeptidase pancreatic lipase o Emulsification occurs via bile acids Bile synthesized in liver stored in gallbladder CCK stimulates constriction of gallbladder to release bile and releases zymogens from pancreas Inhibits gastric emptying Secretin stimulates release of bicarbonate Inhibits gastric emptying GIP inhibits gastric emptying o Co lipase provides lipase access to TAG s o Micelles form which consist of bile acids and phospholipids Transport end products across unstirred water layer to brush border CH2O hydrolysis of oligosaccharides to monosaccharides via oligosaccharidases o Glucose and galactose sodium dependent active transport o Fructose sodium independent GLUT 5 facilitated Protein hydrolysis of oligopeptides to tri and dipeptides and AA diffusion via aminopeptidases On brush border Lipid long chain FA s and MAG s synthesized into TAG s o TAG s CE free cholesterol and phospholipids Louisa Scibelli chylomicrons Mechanisms of absorption o Active transport glucose galactose and AA o Facilitated diffusion fructose GLUT 5 o Diffusion FA s Transport away from intestinal cell FA s Colon o Lymphatic system TAG s as a part of chylomicrons o Absorption of water and electrolytes Factors affecting motility of GI tract o Vascular system portal vein monosaccharides AA glycerol and short chain o Rate of stomach emptying volume of food composition hormones o Intestinal motility increased by motilin and fiber Inhibited by peptide YY and secretin Chapter 4 Fiber Total fiber non digestible plant polysaccharides that contain 1 4 linkages which cannot be digested by humans o Dietary fiber found in foods o Functional fiber added to foods or taken as supplements Soluble fiber soluble in hot water Fermented by bacteria in GI tract o Delays gastric emptying increases transit time decreases nutrient absorption Insoluble fiber doesn t dissolve in water Not fermented by bacteria in GI tract o Decreases transit time and increases fecal bulk Prebiotics are health promoting bacteria found in fermentable fiber Disease and fiber o Heart disease decreased serum cholesterol o Diabetes mellitus better regulation of blood glucose o Obesity increase satiety and decreases absorption of energy nutrients o GI disorders constipation IBS etc o Important to drink lots of water AI 25g day for women and 38g day for men Chapter 5 Glycolysis The oxidation of glucose to pyruvate aerobic or lactate anaerobic o Purpose is to produce energy from glucose Louisa Scibelli o Occurs in the cytoplasm Phosphorylation of glucose o Hexokinase all cells any hexose inhibited by G 6 PO4 allosteric low Km for o Glucokinase liver and pancreas glucose only induced by insulin high Km for glucose glucose Allosteric modification may be positive or negative Regulation is irreversible Major rate controlling enzyme PFK 1 phosphofructokinase 1 Induction increased synthesis of the enzyme and increased amount of the enzyme o Regulated allosterically Inhibited by ATP and citrate Activated by AMP ADP fructose 2 6 bisPO4 o Regulated by induction Insulin increases amount of PFK 1 synthesized Substrate level phosphorylation transfer of PO4 from high energy compound to ADP to form ATP Can occur in cytoplasm and mitochondria ATP s produced 1 Oxidative phosphorylation formation of ATP via ETC Occurs in mitochondria ATP s produced 3 Energetics 4 ATP s produced and 2 NADH s produced Malate shuttle H s attach to NAD to form NADH H 3 ATP s formed Glycerol 3 PO4 shuttle H s attach to FAD to form FADH2 2 ATP s formed Cori cycle lactate formed in muscle from anaerobic glycolysis may be sent to liver for synthesis of glucose This glucose may be returned to muscle Louisa Scibelli Louisa Scibelli Chapter 6 Gluconeogenesis Synthesis of glucose from pyruvate lactate glycerol or selected AA like alanine o Occurs in liver some in kidney during adapted starvation o Energy required Most reactions are simply the reversal of glycolysis expect for o Reversal of PEP to pyruvate o Reversal of F 6 PO4 to F 1 6 bisPO4 o Reversal of glucose to G 6 PO4 Major rate controlling enzyme pryuvate carboxylase o Regulation Induced by glucagon and epinephrine Suppressed by insulin Allosterically modified positively by acetyl CoA and negatively by ADP End substrates of gluconeogenesis lactate and AA are converted to pyruvate while o Requires biotin as cofactor o Mitochondrial enzyme glycerol is converted to DHAP Chapter 7 Glycogen
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