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Flashcards in Carbohydrates Deck (205):
1

Most abundant organic molecules in nature

Carbohydrates

2

Functions of Carbohydrates

1) Energy source2) Storage form of energy3) Part of cell membranes4) Structural components

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Classification of Carbohydrates

1) Monosaccharide - 1 sugar unit2) Disaccharide - 2 sugar unit3) Oligosaccharide - 3-10 sugar unit4) Polysaccharide - >10 sugar unit

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Simplest carbohydrates; Cannot be hydrolyzed further

Monosaccharide

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Condensation products of 2 monosaccharide units; Sugar units are linked by Glycosidic Bonds

Disaccharide

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Glucose + Glucose

Maltose

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Glucose + Galactose

Lactose

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Glucose + Fructose

Sucrose

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Condensation products of 3-10 monosaccharides; Most are not digested by human enzymes

Oligosaccharide

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Condensation product of >10 monosaccharide units; May be linear or branched polymers

Polysaccharide

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Homopolymer of glucose forming an alpha-glucosidic chain, called a Glucosan or Glucan; Most important dietary source of Carbohydrate in cereals, potatoes, legumes and other vegetables

Starch

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Storage polysaccharide in animals; More highly branched structure than amylopectin with chains of 12-14 alpha-D-glucopyranose residues with branching by means of alpha1-6 glucosidic bonds

Glycogen

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Polysaccharide of Fructose used to determine the glomerular filtration rate

Inulin

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Chief constituent of plant cell walls; Insoluble and consists of beta-D-glucopyranose units linked beta1-4 bonds to form long, straight chains strengthened by cross-linking hydrogen bonds; cannot be digested by mammals

Cellulose

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Structural polysaccharide in the exoskeleton of crustaceans and insects

Chitin

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Complex carbohydrates containing amino sugars and uronic acids; They may be attached to a protein molecule to form a proteoglycan

Glycosaminoglycans or Mucopolysaccharides

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Proteins containing branched or unbranched oligosaccharide chains; Occur in cell membranes and many other situations

Glycoproteins or Mucoproteins

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Compounds that have the same chemical formula but different structures

Isomers

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Compounds that differ in configuration around only one specific carbon atom, with the exception of the carbonyl carbon

Epimers

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Pairs of structures that are mirror images of each other

Enantiomers

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Sugars are convertible between a linear form and a ring form; Most are in the cyclic or ring form

Anomers

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Can spontaneously interconvert through a process called

Mutarotation

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Principal sites of Carbohydrate Digestion

MouthIntestinal lumen

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Physical Digestion; Carbohydrate digestion begins during

Mastication

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Chemical digestion of Carbohydrates in mouth

Salivary amylase

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Amylase can only digest ?

Alpha1-4 glycosidic bonds

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Hydrolyzes complex carbohydrates to disaccharides and trisaccharides, but not directly to monosaccharides

Pancreatic amylase

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Disaccharides in the _______ complete the digestive process

Brush border

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Facilitated diffusion; For all sugars

GLUT-1 Transporter

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Facilitated diffusion; For glucose, galactose, and fructose

GLUT-5 Transporter

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Secondary active transport; Na/hexose symporter; For glucose and galactose

SGLT-1 Transporter

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Absorption of sugar requires passage through two membranes:

1) Between lumen and enterocyte2) Between enterocyte and capillary

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Increase in blood glucose after a test dose of a carbohydrate compared with that after an equivalent amount of glucose; Tells how fast a carbohydrate is absorbed references are glucose and galactose

Glycemic Index

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Glycemic Index >1

Fast absorption

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Glycemic Index <1

Slow absorption

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Glycemic Index = 1

Normal absorption

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Sum of ALL the chemical reactions in a cell, tissue, or the whole body; Can either be catabolic or anabolic

Metabolism

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Synthesis of compounds from smaller raw materials; Endergonic and divergent process

Anabolic

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Breakdown of larger molecules; Usually oxidative reactions; Exergonic and convergent process

Catabolic

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Crossroads of metabolism, the link between anabolic and catabolic pathways

Amphibolic

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Regulators of Metabolism: Signals from within the cell

Substrate availability Product inhibitionAllosteric activators/inhibitors

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Regulators of Metabolism: Communication between cells

Direct contactSynaptic signalingEndocrine signalingGap junctionsNeurotransmittersHormones

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Regulators of Metabolism: Second messenger systems

Calcium/inositol triphosphate (ITP)Adenylyl cyclase system (cAMP)Guanylate cyclase system (cGMP)

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Inositol Triphosphate System: G protein used

Gq

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Inositol Triphosphate System: Substrate used

Phosphatidylinositol - found in the cell membrane acted on by phospholipase C

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Inositol Triphosphate System: 2nd Messengers

Diacyl glycerol (DAG) - activate protein kinase CInositol triphosphate (ITP) - release intracellular Ca

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Membrane-bound enzyme that converts ATP to cyclic AMP or cAMP; cAMP hydrolyzed to 5'-AMP by cAMP phosphodiesterase

Adenylyl Cyclase System

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Adenylyl Cyclase System: G protein used

Gs - Stimulates adenylate cyclase, increase cAMPGi - Inhibits adenylate cyclase, decrease cAMP

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Adenylyl Cyclase System: Substrate used

ATP

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Adenylyl Cyclase System: 2nd Messengers

cAMP - activate protein kinase A

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GLUT Transporter: GLUT - 1

Found in: erythrocytes, brain, kidney, colon, placentaFunction: uptake of Glucose

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GLUT Transporter: GLUT - 2

Found in: liver, pancreatic B cell, small intestine, kidneyFunction: rapid uptake and release of Glucose

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GLUT Transporter: GLUT - 3

Found in: brain, kidney, placentaFunction: uptake of Glucose

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GLUT Transporter: GLUT - 4

Found in: heart, skeletal muscle, adipose tissueFunction: insulin-stimulated uptake of Glucose

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GLUT Transporter: GLUT - 5

Found in: small intestineFunction: absorption of Glucose

56

Glycolysis: What is it for?

Major pathway for Glucose Metabolism that converts glucose into 3 carbon compounds to provide energy

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Glycolysis: Where does it occur?

In the cytoplasm, in ALL cells

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Glycolysis: Substrate

Glucose

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Glycolysis: End-product

Pyruvate or lactate, depending on the presence of mitochondria and availability of oxygen

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Glycolysis: Rate limiting Step

Reaction: fructose-6-phosphate ➡️ fructose 1,6-biphosphateEnzyme: phosphofructokimase (PFK-1)

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Cells with mitochondria; Cells with adequate O2 supply; End product: Pyruvate

Aerobic Glycolysis

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Cells without mitochondria; Cells without sufficient O2; End product: Lactate

Anaerobic Glycolysis

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ATP used up to produce phosphorylated intermediates

Energy Investment

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ATP produced through substrate-level phosphorylation

Energy Generation

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Irreversible and Regulated steps in Glycolysis

Step 1: Phosphorylation of GlucoseStep 3: Phosphorylation of Fructose-6-phosphateStep 10: Formation of Pyruvate

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Glycolysis: Step 1

Glucose➡️Glucose-6-phosphateEnzyme: Hexokinase or Glucokinase

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Has a high affinity (low Km) for glucose, and in the liver it is saturated under normal conditions, so acts at a constant rate to provide glucose-6-phosphate to meet the cell's need

Hexokinase

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Has a Km very much higher than the normal intracellular concentration of glucose; Removes glucose from the blood following a meal, providing glucose 6-phosphate in excess of requirements for glycolysis, which is used for glycogen synthesis and lipogenesis

Glucokinase

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Glycolysis: Step 3 - Rate limiting step of Glycolysis

Fructose-6-phosphate➡️Fructose-1,6-biphosphateEnzyme: Phosphofructokinase-1

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Converts fructose-6-phosphate to fructose-1,6-biphosphate; Activator: fructose-2,6-biphosphate and AMP; Inhibitor: ATP and Citrate

Phosphofructokinase-1 (PFK-1)

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Converts fructose-6-phosphate to fructose-2,6-biphosphate; Activator: well fed state - increase insulin, decrease glucagon Inhibitor: starved state - decrease insulin, increase glucagon

Phosphofructokinase-2 (PFK-2)

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Glycolysis: Step 10 - Substrate level phosphorylation that yields 1 ATP per molecule of phosphoenolpyruvate

Phosphoenolpyruvate (PEP)➡️PyruvateEnzyme: pyruvate kinase

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Activator of pyruvate kinase

Fructose-1,6-biphosphate (feedforward mechanism)

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Inhibitor of pyruvate kinase

Increase glucagon + Increase cAMP➡️phosphorylation

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ATP Production in Glycolysis

1) 1,3-biphosphoglycerate➡️3-phosphoglycerateEnzyme: phosphoglycerate kinase2) phosphoenolpyruvate➡️pyruvateEnzyme: pyruvate kinase

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How many net molecules of ATP can be produced from 1 glucose molecule via substrate-level phosphorylation?

2 ATP molecules

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Production of NADH

Step 1: glyceraldehyde-3-phosphate➡️1,3-biphosphoglycerateEnzyme: glyceraldehyde-3-phosphate dehydrogenase

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What happens to pyruvate?

1) pyruvate enters the citric acid cycle (aerobic glycolysis)2) pyruvate reduced to lactate (anaerobic)

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In Aerobic Glycolysis: NADH

Proceeds to Electron Transport Chain

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NADH CANNOT pass through mitochondrial membrane and so needs shuttles

1) Malate-Aspartate Shuttle2) Glycerol Phosphate Shuttle

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In liver, kidney and heart1 NADH = 3 ATP

Malate-Aspartate Shuttle

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In skeletal muscle and brain1 NADH = 2 ATP

Glycerol Phosphate Shuttle

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In what part of the cell can you find the electron transport chain?

Inner mitochondrial membrane

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In Anaerobic Glycolysis, NADH used to

Reduce pyruvate to lactate

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Strictly Glycolytic Organs

RBCsLensCornea of eyeKidney medullaTestesWBCs

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ATP yield of Glycolysis

Anaerobic: 2 ATP Aerobic: 6 (or 8) ATP

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Found in RBCs where phosphoglycerate kinase is bypassed; Reduces hemoglobin affinity for O2

2,3-Bisphosphoglycerate

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Inhibits pyruvate dehydrogenase by binding to lipoic acid; Competes with inorganic phosphate as a substrate for glyceraldehyde-3-phosphate dehydrogenase

Arsenic poisoning (Pentavalent Arsenic)

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Most common enzyme defect in glycolysis; Manifests as chronic hemolytic anemia

Pyruvate Kinase Deficiency

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Low exercise capacity, particularly on high carbohydrate diets

Muscle Phosphofructokinase Deficiency

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Pyruvate kinase deficiency and G6PD deficiency both present with intravascular hemolytic anemia. Important differences are:

1) G6PD has HEINZ BODIES in the peripheral smear2) G6PD often has a precipitating history of oxidative stress

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Alternate Fates of Pyruvate

Pyruvate➡️Acetyl CoAEnzyme: Pyruvate dehydrogenase complex

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Co-enzymes of Pyruvate dehydrogenase complex

1) Lipoic Acid2) NAD3) FAD4) Thiamine pyrophosphate5) Coenzyme A

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Pyruvate➡️Acetyl CoASubstrate?Product?Activator?Inhibitor?

Substrate: PyruvateProduct: Acetyl CoA, NADH, and CO2Activator: NAD+, CoA and pyruvateInhibitor: NADH, acetyl CoA, ATP

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Most common biochemical cause of congenital lactic acidosis; X-linked dominant condition; Increase lactate + Decreased acetyl CoA leads to deprivation of Acetyl CoA in the brain causing psychomotor retardation and death

Pyruvate Dehydrogenase Deficiency

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Treatment of Pyruvate Dehydrogenase Deficiency

Ketogenic Diet

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Alcohol + Nutritional deprivation = Thiamine DeficiencyAn acquired pyruvate dehydrogenase deficiency➡️fatal pyruvic and lactic acidosis

Chronic Alcoholism

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Final common pathway for aerobic oxidation of ALL nutrients; Provides majority of ATP for energy

Tricarboxylic Acid Pathway (TCA) aka Kreb's Cycle or Citric Acid Cycle

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TCA: Where does it occur?

In ALL cells with mitochondria

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TCA: What is the substrate?

Acetyl Coa

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TCA: What are the products?

CO2, GTP, NADH and FADH2

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TCA: Rate limiting step

Reaction: isocitrate➡️alpha-ketoglutarateEnzyme: isocitrate dehydrogenase

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MNEMONIC: Officer Can I Keep Selling Sex For Money

OxaloacetateCitrateIsocitrateKetoglutarateSuccinyl CoASuccinateFumateMalate

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Acetyl CoA + Oxaloacetate ➡️Citrate

Enzyme: Citrate synthase

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Citrate➡️Isocitrate (isomerization)

Enzyme: AconitaseInhibitor: Fluoroacetate (rat poison)

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Isocitrate➡️alpha-ketoglutarate

Rate limiting stepEnzyme: Isocitrate dehydrogenaseProducts: CO2 and NADH

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Alpha-ketoglutarate➡️Succinyl-CoA

Enzyme: alpha-ketoglutarate dehydrogenaseCo-enzyme: similar to pyruvate dehydrogenaseProducts: CO2 and NADHInhibitor: arsenite

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Succinyl-CoA➡️Succinate

Enzyme: succinate thiokinaseProducts: GTP by substrate level phosphorylation

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Succinate➡️fumarate

Enzyme: succinate dehydrogenaseProducts: FADH2

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Fumarate➡️Malate

Enzyme: Fumarase (Fumarate hydratase)

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Malate➡️Oxaloacetate

Enzyme: Malate dehydrogenaseProducts: NADH

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TCA Intermediates: Delivers acetyl CoA to the cytoplasm for fatty acid synthesis via citrate shuttle

Citrate

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TCA Intermediates: Heme synthesis and activation of ketone bodies in extrahepatic tissues

Succinyl CoA

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TCA Intermediates: May be used for gluconeogenesis

Malate

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ATP yield for TCA

Acetyl CoA: 12 ATPPyruvate: 15 ATP (extra 3 ATP - from NADH)

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Production of New glucose

Gluconeogenesis

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Gluconeogenesis from the following intermediates:

1) intermediates of glycolysis and the TCA2) glycerol from triacylglycerols3) lactate through the Cori Cycle4) carbon skeletons (alpha-ketoacids) of glucogenic amino acids

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Gluconeogenesis: Where does it occur?

Liver 90%Kidney 10%Prolonged fasting: Kidney 40%(In both mitochondria and cytoplasm)

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Gluconeogenesis: Substrate

Pyruvate

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Gluconeogenesis: Product

Glucose

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Gluconeogenesis: Rate limiting step

Reaction: Fructose-1,6-biphosphate➡️Fructose-6-phosphateEnzyme: Fructose-1,6-biphosphataseActivator: ATPInhibitor: Fructose-2,6-biphosphate and AMP

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Conversion of lactate to glucose

Cori Cycle

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Cori Cycle: Energy Expense

4 ATP molecules

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True or False: Muscle cannot reconvert lactate to glucose. Lactate must first be transported to the liver for gluconeogenesis.

True

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Important steps in Gluconeogenesis

Step 10: Pyruvate➡️OAA➡️PEPStep 3: Fructose-1,6-biphosphate➡️Fructose-6-phosphateStep 1: Glucose-6-phosphate➡️Glucose

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Requires biotin and ATP; Allosterically activated by Acetyl CoA

Pyruvate carboxylase

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Requires GTP

PEP Carboxykinase

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ALL Carboxylases require ____ as a Co-factor

Biotin

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Promotes Glycolysis and Inhibits Gluconeogenesis

Fructose-2,6-biphosphateActivates: Phosphofructokinase-1➡️favors GlycolysisInhibits: Fructose-1,6-biphosphatase➡️inhibits Gluconeogenesis

130

Final step of Gluconeogenesis which is shared with Glycogen degradation

Glucose-6-phosphate➡️Glucose

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End goal of Glucose-6-phosphate➡️Glucose

Releases free Glucose into the circulation

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Enzyme of Glucose-6-phosphate➡️Glucose

Glucose-6-phosphatase

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Glucose-6-phosphate➡️Glucose: Where does it occur?

Liver and Kidneys only

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Regulation of Gluconeogenesis

1) Circulating levels of Glucagon2) Availability of Glucogenic substrates3) Allosteric activation by Acetyl CoA4) Allosteric inhibition by AMP

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Energy expenditure of Gluconeogenesis

Use of 4 ATPsUse of 2 GTPsOxidizes 2 NADH back to NAD+

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In hyperglycemia, the glomerular filtrate may contain more glucose than can be reabsorbed; Occurs when the venous blood glucose concentration exceeds 9.5-10.0mmol/L (renal threshold)

Glucosuria

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Alcoholism: High amounts of cytoplasmic NADH is formed by:

Alcohol dehydrogenaseAcetaldehyde dehydrogenase

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Hypoglycemia: High amounts of NADH favors the ff reactions:

Pyruvate➡️LactateOAA➡️MalateDHAP➡️Glycerol-3-phosphate

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High fetal glucose consumption; Risk of maternal and fetal hypoglycemia especially during fasting

Hypoglycemia during Pregnancy

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Due to increase estrogen; Fasting Hypoglycemia

Hyperinsulinemia

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Due to increase HPL; Post-prandial hyperglycemia

Insulin resistance

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Premature and LBW babies have little adipose tissue; Enzymes of Gluconeogenesis are not yet completely functional

Hypoglycemia in the Neonate

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Major storage carbohydrate in animals; Branched polymer of alpha-D-glucose

Glycogen

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Glycogen: Where's it stored?

Liver and Muscle onlyLiver: 100g = 6% of liverMuscle: 400g = <1% of muscle

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Synthesis of new glycogen molecules from alpha-D-glucose

Glycogenesis

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Glycogenesis: Where does it occur?

Liver Muscle(Occurs in cytosol)

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Glycogenesis: Substrates

UDP-glucoseATP and UTPGlycogenin - a core, primer protein

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Glycogenesis: Product

Glycogen

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Glycogenesis: Rate limiting step

Reaction: Elongation of glycogenEnzyme: Glycogen synthase

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Important Steps in Glycogenesis

Glucose-6-phosphate➡️Glucose-1-phosphateSynthesis of UDP-GlucoseElongation of Glycogen chainsFormation of branches in glycogen

151

Enzyme of Glucose-6-phosphate➡️Glucose-1-phosphate

Enzyme: Phosphoglucomutase(Reversible - Not a rate limiting step)

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Synthesis of UDP-Glucose: Activated form

Glucose

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Synthesis of UDP-Glucose: Enzyme

UDP-glucose phosphorylase

154

Synthesis of UDP-Glucose: Substrates

Glucose-1-phosphateUTP

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Rate limiting step of Glycogenesis

Elongation of Glycogen chainsEnzyme: Glycogen synthase

156

Formation of branches in glycogen: Enzyme

Branching enzyme composed of amylo alpha(1-4)➡️alpha(1-6) transglucosidase

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Shortening of glycogen chains to produce molecules of a-D-glucose

Glycogenolysis

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Glycogenolysis: Where does it occur?

Liver Muscle(In the cytosol)

159

Glycogenolysis: Substrate

Glycogen

160

Leaves about 4 glucose residues before a branch point

Limit dextrin

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Glycogenolysis: Products

Glucose-1-phosphateFree glucose - produced during the debranching processLiver: can release free glucose to circulationMuscle: limited to glucose-6-phosphate within muscle only

162

Glycogenolysis: Rate limiting step

Reaction: Removal of glucose Enzyme: glycogen phosphorylase

163

Glycogenolysis: Removal of branches

Enzyme: debranching enzymeBonds cleave: alpha(1-4) and alpha(1-6)Products: Free Glucose

164

Conversion of Glucose-1-phosphate to Glucose-6-phosphate

Enzyme: phosphoglucomutaseLiver: Glucose-6-phosphate further converted to glucoseMuscle: Glucose-6-phosphate is the final product

165

Lysosomal degradation of Glycogen

Enzyme: alpha(1-4) glucosidase aka Acid maltase - an enzyme that is different from glycogen phosphorylase

166

Glycogen Storage Disease: Type I

Von Gierke'sGlucose-6-phosphatase deficiencyHypoglycemia + Lactic Acidosis/Ketosis

167

Glycogen Storage Disease: Type II

Pompe'sAcid maltase deficiencyCardiomegaly and heart failure

168

Glycogen Storage Disease: Type III

Cori'sDebranching enzyme deficiencyMilder form of Type I

169

Glycogen Storage Disease: Type IV

Andersen'sBranching enzyme deficiencySevere form of Type I (early death from heart and liver failure)

170

Glycogen Storage Disease: Type V

McArdle'sSkeletal Muscle glycogen phosphorylase deficiencyGlycogen in muscle: Muscle cramps + myoglobinuria but NO lactic acidosis

171

Glycogen Storage Disease: Type VI

Hers'Hepatic Glycogen phosphorylase deficiencyGlycogen in liver cells: hypoglycemia

172

Glycogen Storage Disease: Type VII

Tarui'sPFK deficiencyLike Type V + hemolytic anemia

173

Glycogen Storage Disease: Type VIII

Hepatic phosphylase kinase deficiencyLike Type VI

174

Important source of Galactose

Disaccharide lactose in milk

175

Phosphorylation of galactose

Galactose➡️Galactose-1-phosphateEnzyme: Galactokinase or Hexokinase

176

Formation of UDP-galactose

Galactose-1-phosphate + UDP-glucose➡️UDP-galactose + glucose-1-phosphateEnzyme: galactose -1-phosphate uridyl transferase

177

Use of galactose as carbon source

UDP-galactose➡️UDP-glucoseEnzyme: UDP-hexose-4-epimerase

178

Causes Galactosemia and Galactosuria

Galactokinase Deficiency

179

Absence of galactose-1-phosphate uridyltransferase; Autosomal recessive; Galactitol accumulation - causes Cataracts + Hepatosplenomegaly + mental retardation; Absolute contraindication to breastfeeding

Classic Galactosemia

180

Galactosemia, Galactosuria, cataracts within a few days of birth, vomiting and diarrhea after milk ingestion, hypoglycemia, liver disease and cirrhosis, lethargy and hypotonia, mental retardation; eliminate sources of galactose from the diet

Gal-1-Phosphate Uridyltransferase Deficiency

181

Important source of fructose

Disaccharide sucrose found in honey and fruits

182

Phosphorylation of fructose

Fructose➡️Fructose-1-phosphateEnzyme: Fructokinase or hexokinase

183

Formation of DHAP an Glyceraldehyde

Fructose-1- phosphate➡️dihydroxyacetone phosphate (DHAP) + GlyceraldehydeEnzyme: Aldolase B

184

For Glycolysis; Fructose-1,6-biphosphate➡️DHAP+glycerol-3-phosphate

Aldolase A

185

For Fructose metabolism; Fructose-1-phosphate➡️DHAP+glyceraldehyde

Aldolase B

186

Defect in Fructokinase; Benign and asymptomatic whose only symptom is the appearance of fructose in blood and urine

Essential Fructosuria

187

Deficiency of Aldolase B; Autosomal recessive; Fructose-1-phosphate accumulates leading to decrease phosphate, decrease glycogenolysis, decrease gluconeogenesis; hypoglycemia, jaindice, cirrhosis, vomiting

Fructose Intolerance

188

Important component of Glycoprotein

Mannose Metabolism

189

Isomerization between mannose and fructose

Mannose-6-phosphate➡️fructose-6-phosphateEnzyme: phosphomannose isomerase

190

Glucose➡️Sorbitol

Enzyme: Aldose reductaseFound in lens, retina, Schwann cells, liver, kidney, placenta, RBC, ovaries, seminal vesicles

191

Sorbitol➡️Fructose

Enzyme: Sorbitol dehydrogenaseFound in the seminal vesicles only since Fructose is the fuel of sperm

192

Pentose Phosphate Pathway: What is it for?

1) Produces NADPHFA and Steroid biosynthesisReduction of GlutathioneCytochrome p450WBC respiratory burstNitric oxide synthesis2) Produces Ribose-5-phosphate for nucleotide synthesis3) Metabolic use of 5-carbon sugars

193

Pentose Phosphate Pathway: Where does it occur?

In the cytoplasmActive in: Liver, Adipose tissue, Adrenals, Thyroid, Testes, RBC, Lactating membranesLow in: skeletal muscle, non-lactating mammaries

194

Pentose Phosphate Pathway: Substrate

Glucose-6-phosphate(No consumption or production of ATP)

195

Pentose Phosphate Pathway: Products

Ribose-5-phosphateFructose-6-phosphateGlyceraldehyde-3-phosphateNADPH

196

Pentose Phosphate Pathway: Rate limiting step

Reaction: glucose-6-phosphate➡️6-phosphogluconateEnzyme: glucose-6-phosphate dehydrogenase

197

Pentose Phosphate Pathway: Phase 1

OxidativeIrreversibleEnzyme: glucose-6-phosphate dehydrogenaseProduct: NADPH ribulose-5-phosphate

198

Pentose Phosphate Pathway: Phase 2

Non-oxidativeReversibleEnzyme: Transketolase (requires Thiamine)Product: ribose-5-phosphate, glyceraldehyde-3-phosphate, fructose-6-phosphate

199

Removes H2O2 in reaction catalyzed by glutathione peroxidase; very important in RBCs

Glutathione

200

Reduced glutathione sequester harmful H2O2

Enzyme: glutathione peroxidase

201

Reduced glutathione recreated using NADPH

Enzyme: glutathione reductase

202

Most common disease producing enzyme abnormality in humans; Involves decrease NADPH in RBCs and decrease activity of glutathione reductase causing free radicals and peroxides to accumulate

Glucose-6-phosphate Dehydrogenase Deficiency

203

Precipitating factors of Glucose-6-phosphate Dehydrogenase Deficiency

Infection - most commonDrugs - antibiotics (sulfonamides, chloramphenicol), antimalarials (primaquine), antipyretics (except ASA and paracetamol)Fava beans

204

Altered RBCs due to phagocytic removal of Heinz bodies in spleen

Bite cells in Heinz Bodies

205

Deficiency in NADPH oxidase; severe, persistent and chronic pyogenic infections

Chronic Granulomatous Disease