Biochem - Block 2 - Part 1

davidwurbel7's version from 2015-04-19 05:52

Enzyme Phosphorylation Active/Inactive State

Question Answer
PFK-2 phosphorylatedInactive
PFK-2 dephosphorylatedActive
Pyruvate kinase phosphorylatedInactive
Pyruvate kinase dephosphorylatedActive
Pyruvate dehydrogenase phosphorylatedInactive
Pyruvate dehydrogenase dephosphorylatedActive
Glycogen Synthase phosphorylatedInactive
Glycogen Synthase dephosphorylatedActive
Glycogen Phosphorylase Kinase phosphorylatedActive
Glycogen Phosphorylase Kinase dephosphorylatedInactive
Glycogen Phosphorylase a phosphorylatedActive
Gylcogen Phosphorylase b dephosphorylatedInactive
Acetyl CoA Carboxylase dephosphorylatedActive
Acetyl CoA Carboxylase phosphorylatedInactive

Metabolic Reactions (Glycolysis, TCA cycle, Gluconeogenesis, Alcohol Metabolism)

Question Answer
Reactions catalyzed by Hexokinase/Glucokinase, PFK-1, Pyruvate kinaseIrreversable
What enzyme is the rate limiting enzyme of glycolysisPFK-1
The only oxidation-reduction reaction of glycolysis producting NADH + H+Glyceraldehyde 3-phosphate dehydrogenase
1,3 Bisphosphoglycerate to 3-Phosphoglycerate resulting in the production of ATPPhosphorglycerate kinase
Fluoride inhibits Enolase
Phosphoenolpyruvate to Pyruvate resulting the production of ATPPyruvate Kinase
Deficiency of this enzyme leads to hemolytic anemiaPyruvate Kinase
Has low Km (0.05 mM) and low Vmax for glucoseHexokinase
Located into most tissuesHexokinase
Isoenzyme form of Hexokinase and is present in hepatocytes and beta-cells of pancreasGlucokinase
Has higher Km (5 mM) and high Vmax for glucoseGlucokinase
Along with the hypothalamus acts as a glucose sensor in the maintenance of blood glucose homeostasisGlucokinase
Inhibited by the reaction product glucose-6-phosphateHexokinase
Induced by insulin in hepatocytes, not inhibited by glucose-6-phosphateGlucokinase
ATP and citrate are negative allosteric modulatorsPFK-1
AMP and fructose 2,6-bis-phosphate are positive modulators PFK-1
Insulin stimulatesPFK-1
Glucagon inhibitsPFK-1
In gluconeogenesis, pyruvate converted to oxaloacetate is done byPyruvate Carboxylase
Oxaloacetete is converted into phosphoenolpyruvate is done byPhosphoenolpyruvate Carboxykinase
Fructose 1,6-bisphosphate is converted to fructose 6-phosphate byFructose 1,6-Bisphosphatase
Glucose 6-phosphate is converted to glucose byGlucose 6-Phosphatase
Converts ethanol to toxic molecule acetaldehyde by using a reduction of NAD+ to NADHAlcohol Dehydrogenase
Converts acetaldehyde to acetate by using a reduction of NAD+ to NADHAcetaldehyde Dehydrogenase

Glycogen Synthesis and Glycogen Degradation

Question Answer
Adds UDP-glucose to nonreducing ends of the chainGlycogen Synthase
When the chain reaches approximately 11 residues in length, a 6- to 8-residue piece is cleaved and reattached to a glucosyl unit by an α-1,6-bond Amylo 4:6-Transferase (Branching Enzyme or 4,6 Transferase)
Cleaves α-1,4 glycosidic bond between glucosyl residues at the nonreducing ends releasing them as glucose-1-phosphateGlycogen Phosphorylase
Removes the glucose residues from nonreducing ends until four glucose residues remain on each chain before a branch pointGlycogen Phosphorylase
Two catalytic activities: amylo 4:4 transferase and α -1,6 glucosidaseDebranching Enzyme
Removes a unit containing three glucose residues and adds it to the nonreducing ends with longer chain by an α-1,4 glycosidic bondAmylo 4:4 Transferase (4:4 Transferase)
Removes one glucose residue remaining at the α-1,6-branch resulting in the release of free glucoseα-1,6 Glucosidase


Question Answer
Deficiency of aldolase B enzymeHereditary Fructose Intolerance
This condition is characterized by an increase in 2,3-BPG, mild to moderate chronic hemolytic anemia, and the absence of Heinz bodies Pyruvate Kinase Deficiency
An X-linked dominant condition with symptoms and signs include neurodegeneration, muscle spasticity, congenital lactic acidosis and early death.Pyruvate Dehydrogenase (PDH E1) Deficiency
Results from defects in mitochondrial ATP production, as a result of mutations in the PDH complex, electron transport chain or ATP synthase; or deficiency of thiamine or niacin as brain is unable to produce sufficient ATP if the PDH complex is inactive.Leigh syndrome (subacute necrotizing encephalomyelopathy)
Mainly affects people of African, Middle Eastern and South Asian descent, generally asymptomatic unless triggered by certain drugs increasing reactive oxygen species which include anti-malarial, sulfonamides, certain analgesics, some non-sulfa antibiotics Glucose-6-Phosphate Dehydrogenase (G6PDH) Deficiency
Increase in 2,3 BPG, presence of Heinz body, sever hemolytic anemiaGlucose-6-Phosphate Dehydrogenase (G6PDH) Deficiency
A deficiency or defect in fructokinase, a benign condition and patient remains nearly asymptomatic, fructose appears in urineEssential Fructosuria
Deficiency or defect in aldolase B with symptoms appearing when fruit juices are introduced for the first time, hypoglycemia, hyperuricemia, lactic acidosis, and jaundiceHereditary fructose intolerance (HFI)
Due to deficiency of galactokinase, galactosemia, galactosuria, accumulation of galactitol in lens leads to development of cataract, Mental retardation is NOT seenNon-Classical Galactosemia
Due to deficiency of galactose 1-phosphate uridyl transferase enzyme (GALT). Accumulation of galactitol in lens leads to development of cataract, hyperbilirubinemia, jaundice, mental retardation.Classical Galactosemia
Due to deficiency of glucose-6-phosphatase, inability to maintain an adequate blood glucose level, doll-like face with fatty cheeks, protuberant abdomen that is due to massive hepatomegaly, renomegaly, lactic acidosis, keto acidosis, hyperlipidemia, hyperuricemia, hyperventilation and apparent respiratory distressvon Gierke’s Disease
Due to Deficiency of lysosomal acid α-1,4 glucosidase or α-1,6 glucosidase or both (acid maltase), signs of muscle weakness, severe muscle weakness, resulting in an overall “floppy baby” appearance because of poor muscle tone, head, hands, legs fall outward into a “frog-like” position, difficulty sucking and swallowing, enlarged tongue, failure to meet developmental milestones such as rolling over, sitting up, crawling, and walking, or regression, severe cardiomegaly, heart rhythm changes and heart failure, difficulty breathing and respiratory infections with eventual respiratory failurePompe's Disease
Due to deficiency of muscle glycogen phosphorylase, exercise intolerance with muscle cramps, myoglobinuria after exercise, serum creatine kinase (CK-MM) is usually elevated at rest and increases after exercise, increases the levels of blood ammonia, inosine, hypoxanthine, and uric acidMcArdle’s Disease
Due to defect or deficiency of phosphofructokinase in muscle and erythrocytes (RBCs). Prevalent in Ashkenazi Jews and Japanese population, exercise intolerance with muscle cramps, myoglobinuria after exercise, serum creatine kinase (CK-MM) is usually elevated at rest and increases after exercise, hemolytic anemia leading to increased bilirubin levels and jaundiceTarui's Disease
Due to deficiency or defect in branching enzyme, accumulation of glycogen with long outer branches with very few branch points, failure to thrive, hypotonia, hepatomegaly, splenomegaly, progressive liver cirrhosis and failureAnderson Disease
Due to deficiency or defect in debranching enzyme, accumulation of glycogen with short outer branches, hepatomegaly, growth retardation, muscle weakness, hypoglycemiaCori or Forbes Disease
Lactic acidosis, hypoglycemia, mental retardation, hyperammonemia, hypotoniaPyruvate Carboxylase Deficiency
Condition seen with high levels of alcohol dehydrogenase converting alcohol to acetaldehyde but low levels of acetaldehyde dehydrogenase converting acetaldehyde to acetateAlcohol Flush Reaction (Asian Flush Syndrome)
Inhibition of fatty acid oxidation due to high NADH/NAD ratio and stimulation of triacylglycerol synthesis. It can also result in ketoacidosis or lactic acidosis and cause hypoglycemia or hyperglycemia, depending on the dietary state. These effects are considered reversible.Fatty Steatosis (Fatty Liver)
Replacement of hepatocytes with Type I collagen fibers leading to reduction of liver functionLiver Cirrhosis
A group of lysosomal storage diseases in which there is a deficiency of one or more of the acid hydrolase enzymes. Can present in three ways: As a dysmorphic syndrome; with learning difficulties, Behavioral disturbance and dementia; As a severe bone dysplasia.Mucopolysaccharidoses
Hepatosplenomegaly, coarse facial features and macroglossia, hearing loss, progressive learning difficulties, kyphoscoliosis and corneal clouding and cardiomyopathy. Dermatan sulfate (DS) and heparan sulfate (HS) seen upon urinalysisHurler Syndrome
Deficiency of the enzyme α-L-IduronidaseHurler Syndrome
Hepatosplenomegaly, coarse facial features and an enlarged tongue, hearing loss, progressive learning difficulties, cardiomyopathy maybe seen, prominent Mongolian blue spots and a papular rash. Dermatan sulfate (DS) and heparan sulfate (HS) seen upon urinalysis Hunter Syndrome
Deficiency of Iduronate sulfataseHunter Syndrome
Physical defects are relatively mild, while the mental retardation is severe. First phase: consists of developmental delay alone, often primarily affecting speech. Second phase: severe behavioral disturbance, characterized by hyperactivity, challenging behavior and profound sleep disturbance. Third Phase: continuing loss of skills and slow deterioration into a vegetative state. Heparan sulfate (HS) seen upon urinalysisSanfilippo Syndrome
Deficiency of multiple acid hydrolasesSanfilippo Syndrome
Presents with severe motor and cognitive retardation. Skeletal abnormalities (kyphoscoliosis, dwarfism), hepatosplenomegaly, macroglossia, corneal clouding, repeated respiratory infectionI-cell Disease
Patients are severely deficient in the activity of GlcNAc phosphotransferase (N-acetylglucosamine phosphotransferase)I-cell Disease
The inclusion bodies contained macromolecules that could be stained with Sudan black B (lipids) and periodic acid Schiff (PAS; glycogen)I-cell Disease
Decay accelerating factor (DAF) and CD59 are not properly anchored to red blood cells because of the faulty GPI linkage. Without these proteins linked to the cell surface the complement system can lyse RBC's. All other cells have transmembrane forms of DAF and CD59Paroxysmal Nocturnal Hemoglobinuria
Diagnosed by using Ham's test (dropping the blood pH). RBCs lyse at pH 6.2. Normal RBCs do not lyseParoxysmal Nocturnal Hemoglobinuria
Deficiency of dipamitoyl lecitihin (dipalmitoyl phosphotidylcholine) in infantsInfant Respiratory Distress Syndrome
Usually seen in infants born at 26-28 weeks and begins shortly after birth and is manifest by tachypnea, tachycardia, chest wall retractions (recession), expiratory grunting, flaring of the nostrils and cyanosis during breathing effortsInfant Respiratory Distress Syndrome
Lingual lipase and gastric lipase play an important role in lipid digestion in infants and young children and those with pancreatic insufficiency due to the pancreatic ducts are blockedCystic Fibrosis
Deficiency of essential fatty acids (Linoleic acid and Linolenic acid) due pancreatic lipase not getting into the duodenumCystic Fibrosis
Presence of excess fat in feces. Stools having oily appearance, difficult to flush and foul smellingSteatorrhoea
Common sign seen in Pancreatitis, Cystic fibrosis, Crohn's disease, Short bowel syndrome, Pancreatic carcinoma, Tropical sprue, Coeliac disease, Liver disease, Diverticular disease due to fatty acid maldigestion and/or malabsorptionSteatorrhoea
Biological causes include lack of bile acids (due to liver damage, cholecystectomy), defects in or deficiency of pancreatic enzymes and defective mucosal cellsSteatorrhoea


Question Answer
The type of glycolysis that results in 2 ATP, + 2 NADH+2H+ (each NADH+H in electron transport chain will produce 3 ATPs), so the net ATPs produced is 2+6 = 8Oxidative Glycolysis
The type of glycolysis in which glucose to 2 lactate: 4 ATP – 2 ATP = 2 ATPAnerobic Glycolysis
Cancer cells conduct ________ in the presence of oxygen but do not conduct TCA or ETCAerobic Glycolysis
This shuttle produces a mitochondrial NADH and yields approximately 3 ATP by oxidative phosphorylationMalate Shuttle
This shuttle produces a mitochondrial FADH2 and yields approximately 2 ATP by oxidative phosphorylation.Gycerol Phosphate Shuttle
Glycolysis + ________ = 8 ATPMalate Shuttle
Glycolysis + ________ = 6 ATPGlycerol Phosphate Shuttle
Glycolysis + ________ + ETC = 38 ATPMalate Shuttle
Glycolysis + ________ + ETC = 36 ATPGlycerol Phosphate Shuttle

TCA Cycle and Pentose Phosphate Pathway

Question Answer
This needs Thiamine pyrophosphate, Lipoate (lipoic acids), NAD+ (niacin derivative), FAD (riboflavin derivative) and Reduced Coenzyme A for its complete catalytic activityPyruvate Dehydrogenase Complex
The key regulatory enzyme for TCA cycle. It is considered as rate limiting enzyme for TCA cycleIsocitrate Dehydrogenase
Catalyzes the oxidative decarboxylation of isocitrate transferring electrons to NAD+ to generate NADH+H, and also releases one carboxylate group (COO-)as CO2.Isocitrate Dehydrogenase
Structurally and functionally similar to PDC complex and requires all the coenzymes required for PDC. It causes second oxidative decarboxylation in TCA cycleAlpha-Ketoglutarate Dehydrogenase Complex
Causes second oxidative decarboxylation in TCA cycle, removing one of the carboxylate (COO-) group as CO2, and transfers electrons to NAD+ to form NADH+H. Alpha-Ketoglutarate Dehydrogenase Complex
Energy from succinyl CoA thioester bond to succinate is used to generate GTP from GDP and inorganic phosphate (iP) is catalyized by Succinate thiokinase
Increased levels of _____ increases the rate of TCA cycleADP
Increased levels of ______ inhibits the rate of TCA cycleNADH
This enzyme is one of the major anapleurotic enzyme in the cellPyruvate Carboxylase
The rate limiting enzyme of the pentose phosphate pathway is Glucose-6-phosphate dehydrogenase
Lipid synthesis and cholesterol synthesis; Reduction of hydrogen peroxide (H2O2); Glutathione peroxidase neutralizes H2O2 using reduced glutathione (GSH).NADPH + H+
Adds –OH to substrate to makes it water-soluble. The substance is then eliminated in the urineCytochrome P450 monooxygenase
Used in the biosynthesis of steroid hormonesMitochondrial cytochrome P450 monooxygenase
Associated with smooth ER (specially in liver), involved in drug detoxificationMicrosomal cytochrome P450 monooxygenase