RU BL 616 - Lecture Notes (6 pages)

Previewing pages 1, 2 of 6 page document View the full content.
View Full Document

Lecture Notes



Previewing pages 1, 2 of actual document.

View the full content.
View Full Document
View Full Document

Lecture Notes

145 views


Pages:
6
School:
Regis University
Course:
Bl 616 - Biomedical Biochemistry
Unformatted text preview:

Chapts 27 31 topics Chapt 27 Carbohydrates digestion Chapts 27 31 Carbohydrate topics Carbohydrates are major source of calories 40 Digested by specific enzymes Starch plants amylase Lactose galactosidase lactase Fig 1 sugars Sucrose sucrase High fructose syrup Student Learning Outcomes Explain basic processes of digestion absorption and transport of carbohydrates and lactose intolerance Describe formation degradation of glycogen Describe essentials of other sugar metabolism Isomerized from starch Cellulose is fiber Pentose phosphate path fructose galactose Describe the basic path of gluconeogenesis Glycosidases cleave carbohydrates Disaccharidases Overview of carbohydrate digestion absorption amylases saliva pancreas Disaccharidases located in intestinal brush border Hydrolyze disaccharides Fig 4 5 Anchored in membrane Saliva starts breakdown Pancreatic enzyme in intestine Are glycosylated Two enyzme activities Disaccharidases in intestine Monosaccharides enter blood through intestinal epithelium Table 1 Ex Sucrase isomaltase 1 4 bond 1 6 1 4 facilitative diffusion transporters or Na dependent glucose transporters Fiber and remaining compounds digested by bacteria in colon Transmembrane N end Fig 2 1 glycosidase complex Fiber glycosidase complex glycoprotein Anchored as phosphtidylglycan to COOH end Lactase hydrolyzes lactase Other enzyme does glycolipids glucose ceramide Fiber is indigestible carbohydrates Colonic bacteria metabolize leftover saccharides Fig 10 6 Fig 9 Lactose intolerance Lactose intolerance see Table 2 Low levels lactase late onset Adult levels are low in many populations Injestion of lactose pain nausea flatulence diarrhea Can mix lactase enzyme with food first Generate gas H2 CO2 CH4 Lactate Short fatty acids Acetic butyric Some absorbed by body Incomplete digestion products lead to diarrhea Fig 10 Absorption of sugars Sugars are absorbed through intestinal epithelia Glucose through Na dependent transporters let in Na and glucose galactose also can concentrate Glucose through facilitated transport GLUT 1 5 Different isoforms 12 membrane spans Fructose and galactose Use glucose transporters Fig 12 2 Insulin and GLUT4 Synthesis of glycogen Insulin stimulates glucose transport into muscle and adipose cells by increasing transporters Glucose goes through cells blood brain barrier Chapt 28 Synthesis degradation of glycogen 1 4 glycosidic 1 6 branches protein glycogenin on end Major role in liver is blood glucose Major role in muscle is ATP Some people have defects glycogen metabolism Figs 13 14 Fig 28 1 2 Glycogen synthesis and degradation Glycogen synthesis and degradation Different enzymes for synthesis degradation Glycogen has branch every 8 10 glucose residues Starts and ends with glucose 1 Phosphate Careful regulation Synthesis UDP G pyrophosphorylase Synthesis branching helps solubility more sites for synthesis and degradation costs 1 UTP 2 P P each UDP G other paths Figs 28 5 6 Degradation Glycogen synthase Branching enzyme Degradation Debrancher enzyme Glycogen phosphorylase Phosphorylase uses Pi to break Branching enzyme does residues near branch Branch sugar yield glucose not PO4 Fig 3 3 Regulation of glycogen metabolism is critical Regulation of glycogen in liver responds to hormones glucagon epinephrine via cAMP PKA Muscle glycogenolysis Exercise activates muscle glycogenolysis Initiated by muscle contraction nerve impulse or epinephrine AMP allosteric activator of glycogen phosphorylase Fig 9 8 Nerve signal Ca2 release binds calmodulin Fig 9 10 Activates phosphorylase kinase Reciprocal phosphates activate inhibit Glycogen synthase PO4 inhibit Epinephrine through PKA activates same phosphorylase kinase Phosphorylase kinase Glycogen phosphorylase PO4 activates Result active PO4 Glycogen phosphorylase and glucose 1 P Phosphatases remove PO4 Dotted lines decreased in fasting state Fig 11 Fig 8 Ch 29 Pentose phosphate pathway fructose galactose Fructose Metabolism of other sugars Fructose common in diet Fructose is metabolized to intermediates of glycolysis Sucrose high fructose corn syrup Fructokinase forms F 1 PO4 Essential fructosuria people lack enzyme Aldolase critical 3 isoforms Galactose from lactose Metabolized to glycolysis intermediates Hereditary defect diseases Pentose phosphate path Forms reducing power NADPH for detoxification biosynthesis Forms 5 C sugars for nucleotides bypass part of glycolysis All do glycolysis F 1 6 P Fig 1 fructose Only Aldolase B Cleaves F 1 P Hereditary fructose intolerance can be fatal accumulate F 1 P in liver impaired gluconeogenesis glycogenolysis hypoglycemia Fig 3 4 Galactose Pentose phosphate pathway Galactose is converted to Glucose 1 P Galactokinase forms Gal 1 P Galatose 1 P uridylyltransferase forms Glucose 1 P uses UDP glucose and forms UDP galactose Epimerase can regenerate UDP glucose Lot of galactose from Lactose Classic galactosemic accumulates Gal 1 P liver impaired glycogen synthesis Pentose phosphate pathway Bypass of part of glycolysis Generates NADPH reducing power Biosynthesis fatty acids Cholesterol DNTP Detox reactions 5 C sugars ribose PO4 Can rearrange back into glycolysis compounds Regulation by cell needs Fig 2 Fig 5 Gluconeogenesis essentials Gluconeogenesis Gluconeogenesis in the liver makes glucose Critical need for glucose especially red blood cell brain During fasting liver mobilizes glycogen makes new glucose from noncarbohydrates Gluconeogenesis Main precursors are lactate glycerol amino acids Many steps are reversals of glycolysis reactions 3 critical irreversible steps have separate enzymes these also regulated see also Chapters 1 3 Fig 2 Fig 1 5 Gluconeogenesis occurs in mitochondrion and cytosol Gluconeogenesis Complex conversion of pyruvate back to PEP vs oxidation of PEP by pyruvate kinase PDC Mitochondrion cytosol Blood glucose sources Sources of blood glucose in fed fasting starved Liver uses glycogenolysis Muscle uses its glycogen not contribute to blood level lack G 6 Phosphatase Gluconeogenesis spares body protein Gluconeogenesis is highly regulated Fig 5 Fig 20 Review question Chapt 27 Review question Ch 29 After digestion of a piece of cake that contains flour milk and sucrose as its primary incredients the major carbohydrate products that enter the blood are which of the following a glucose b fructose and galactose c galactose and glucose d fructose and glucose e glucose galactose and fructose 29 1 Hereditary fructose intolerance is a rare recessive genetic diseases


View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view Lecture Notes and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Lecture Notes and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?