Biochem - Final - Part 2

davidwurbel7's version from 2015-04-19 22:30


Question Answer
The average pKa for α-carboxylic acid groups is~2 (1.8 to 2.4)
The average pKa for α-amino groups is ~9.5 (8.8 to 11.0)
What are the essential amino acidsPhenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Arginine, Leucine and Lysine
Precursor to neurotransmitters dopamine, norepinephrine and epinephrineTyrosine
Precursor to melaninTyrosine
Precursor to T3 and T4 Tyrosine
Precursor to neurotransmitters serotonin and melatonin and to vitamin niacinTryptophan
Precursor of S-adnosylmethionine (SAM)Methionine
Methyl group donor in the synthesis of creatine and epinephrineS-adnosylmethionine (SAM)

Enzymatic Panel Test

Question Answer
Myocardial infarction, muscle injuryCreatine kinase (CK)
Myocardial infarctionCK2 - MB
Muscular dystrophy or muscle damageCK3 - MM
Myocardial infarction, liver diseaseLactate dehydrogenase (LDH)
Myocardial infarctionLDH1
Megaloblastic anemiaLDH2
Leukemia, malignancyLDH3
Pulmonary infarctionLDH4
Liver disease, muscle injuryLDH5
Acid phosphataseProstatic cancer
Jaundice, rickets, osteomalaciaAlkaline phosphatase
Pancreatitis, perforation of intestineAmylase
Pancreatitis, bile duct obstructionLipase
Myocardial infarction, hepatitis, muscle damageAST
Hepatitis, alcoholic liver damageGGT
Appears in plasma 3-6 hrs following chest pain, reaches peak of activity at 12-24 hrs and returns to baseline after 48-72 hrs.CK2 - MB
Appears in plasma 48 hrs following chest pain, reaches peak of activity at 72 - 96 hrs (3rd-4th day) and takes about 10 days to reach normal levels.LDH1
Cardiac protein, highly sensitive and specific for cardiac damage, it appears in plasma 4-8 hrs following chest pain, reaches peak of activity at 12-24 hrs and takes about 7-10 days to reach normal levels.Cardiac Troponin I (cTI)

Carbohydrate Digestion

Question Answer
α 1-4 Gylcosidic bondMaltose
α 1-2 Gylcosidic bondSucrose
α 1-6 Glycosidic bondIsomaltose
β 1-4 Glycosidic bondLactose
Digestion of carbohydrates begins with Salivary α-amylase
Digestion of carbohydrates continues with Pancreatic α-amylase
Oligosaccharides are digested byα – glucosidase
Glucose transporter protein found in the blood-brain barrier, RBCs, blood-renal barrier, blood-placental barrier, blood-testis barrierGLUT 1
Glucose transporter protein found in the liver and β-cells of the pancreasGLUT 2
Glucose transporter protein found in the brainGLUT 3
Glucose transporter protein found in skeletal muscle, adipose tissue, cardiac muscleGLUT 4
Actually a fructose transporter found in spermGLUT 5

Glycolysis and TCA

Question Answer
1 glucose converted into 2 lactateAnaerobic glycolysis
1 glucose converted into 2 pyruvateAerobic glycolysis
Glycolysis result is 2 ATP, 2 NADH and 2 pyruvate (8 ATP)Aerobic glycolysis
Glycolysis result is 2 ATP, 2 NAD+ and 2 lactate (2 ATP)Anaerobic glycolysis
This needs Thiamine pyrophosphate, Lipoate (lipoic acids), NAD+ (niacin derivative), FAD (riboflavin derivative) and Reduced Coenzyme A for its complete catalytic activityPyruvate Dehydrogenase Complex

Glycolysis Reactions

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

Uncouplers and Inhibitors of ETC

Question Answer
Decreased oxygen consumption; Increased intracellular NADH/NAD and FADH2/FAD ratio; Decreased ATP synthesis.Inhibitors of ETC
Increased oxygen consumption; Decreased intracellular NADH/NAD and FADH2/FAD ratio; Decreased ATP synthesis.Uncouplers of ETC
RotenoneInhibitor, Complex I, ETC
Antimycin AInhibitor, Complex III, ETC
CyanideInhibitor, Complex IV, ETC
Carbon MonoxideInhibitor, Complex IV, ETC
AzideInhibitor, Complex IV, ETC
Hydrogen sulfideInhibitor, Complex IV, ETC
OligomycinInhibitor, ATP synthase, ETC
ThermogeninUncoupler, Proton carrier, ETC
2, 4-DinitrophenolUncoupler, Proton carrier, ETC
Thyriod hormoneUncoupler, Proton carrier, ETC
AspirinUncoupler, Proton carrier, ETC

Polyol Pathway

Question Answer
Aldehyde group in glucose is converted into a hydroxyl group formingSorbitol
Conversion of glucose into sorbitolAldose Reductase
Enzyme present in the liver, ovaries and seminal vesicles to produce fructose from sorbitolSorbitol Dehydrogenase

Galactose Metabolism

Question Answer
Enzyme that phosphorylates galactoseGalactokinase
Enzyme that catalysis the exchange of UDP and phosphate between galactose-1-phosphate and UDP-glucoseGalactose 1-Phosphate Uridyl Transferase (GALT)
Enzyme that converts UDP-galactose into UDP-glucoseEpimerase

Pentose Phosphate Pathway

Question Answer
The rate limiting enzyme of the pentose phosphate pathway isGlucose-6-phosphate dehydrogenase
Enzyme present in RBCs that can be tested for thiamine levelsTransketolase
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

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
The ratio of glucose to glucose-1-phosphate released from each branch point of glycogen1:9


Question Answer
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

Ethanol Metabolism

Question Answer
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
Acetate can then be converted into acetyl CoA and entersTCA Cycle

Proteoglycans and Glycosaminoglycans

Question Answer
All amino sugars found in glycoproteins are derivatives ofGlucosamine-6-Phosphate
The precursors for the addition of four of the seven sugars that are usually found in glycoproteins – glucose, galactose, N-acetylglucosamine, and N-acetylgalactosamineUDP-Sugars
The precursors for the addition of mannose and L-fucoseGDP-Sugars
The precursor of NANA (N-acetylneuraminic acid, also called as sialic acid)CMP-NANA
Synthesized by sequential addition of nucleotide sugars on the protein (Serine, Threonine, or Tyrosine) by specific glycosyltransferasesO-linked Glycosaminoglycans
Glycosidic bond forms between xylose and Serine or GalNAc and Serine (only found in keratan sulfate II)O-linked Glycosaminoglycans
Involves dolichol phosphate in transferring branched sugar chains to the amide nitrogen of Asparagine residuesN-linked Glycosaminoglycans
The key lipid that acts as an acceptor for other sugars in the assembly of Dol-P-P-oligosaccharideDolichol-P-P-GlcNAc (Dol-P-P-GlcNAc)
Enzymes destined to lysosomes are targeted to lysosomes by a specific chemical markerMannose-6-Phosphate
Patients with I-cell disease are severely deficient in the activity ofGlcNAc phosphotransferase (N-acetylglucosamine phosphotransferase)
The receptor for this marker is located in the trans-Golgi for targeting an enzyme to the lysosomeMannose-6-Phosphate

Blood Groups

Question Answer
GlacNAc attached to Galactose attached to FucoseH Substance
GlacNAc attached to Galactose of the H SubstanceType A
N-acetylgalactosamine transferase attaches GlacNAc to Galactose of the H SubstanceType A
Galactose attached to Galactose of the H SubstanceType B
Galactose transferase attaches to Galactose of the H SubstanceType B
GlacNAc attached to Galactose of the one H Substance and Galactose attached to Galactose of another H SubstanceType AB
Active N-acetylgalactosamine transferase and Galactose transferaseType AB
Neither GlacNAc or Galactose attached to Galactose of the H SubstanceType O
Defective N-acetylgalactosamine transferase and Galactose transferaseType O


Question Answer
Fatty acids that cannot be synthesized by the human body are the ω-6 and ω -3 fatty acidsEssential Fatty Acids
Part of the ω-6 family, an essential FA that can be used to make arachidonic acid which is an important precursor for prostaglandins, throbaxanes, and leukotriensLinoleic Acid
Part of the ω-3 family, used to make eicosapentenoic acid which is a precursor for many eicosanoidsLinolenic Acid
The replacement of omega-6 family arachidonic acid with _________ in platelet membranes decreases synthesis of thrombaxene which is know to induce platelet aggregation, hence decreased risk of atherogenesis and coronary artery clot formationOmega-3 Fatty Acids
These fatty acids decrease membrane fluidity and increase the risk of atherosclerosisTrans-Fatty Acids
Glycerophospholipid with a phospholipid backbone and cholinePhosphatidylcholine (Lecithin)
Most abundant in cell membrane. Storage form of choline in the body. Choline is involved in neurotransmission and methylation reactionPhosphatidylcholine (Lecithin)
Found in the alveoli in the lungs and acts as surfactant in alveoli of lungs and maintains surface tension and prevents alveolar collapseDipamitoyl Lecithin

Metabolism of Lipids

Question Answer
Digestion of lipids begins in the _______, catalyzed by lingual lipase and gastric lipaseStomach
Lingual lipase and gastric lipase are acid stable with an optimum pH range of4 to 6
Lingual lipase and gastric lipase primarily targetShort or Medium Chain Fatty Acids
Pancreatic lipase will targetShort or Medium or Long Chain Fatty Acids
Stimulates the release of pancreatic juices from the pancreas, contraction of the gallbladder and reduces the contraction of the stomachCholecystokinin
Stimulates the release of bicarbonate mostly from the pancreas and some from the liverSecretin
Coating of dietary lipids with bile acids and salts to increase the surface areaEmulsification
Bile acids and salt inhibit the action of _____Pancreatic Lipase
Enzyme that interacts with bile acids and salt to inhibit the inhibitory effect of bile acids and salts on pancreatic lipaseColipase
Emulsified fat globule containing undigested fatty acids, cholesterol, and vitamins A, D, E and KMicelle
Emulsified fat globule containing digested fatty acids, cholesterol, and vitamins A, D, E and KMixed Micelle
The length of fatty acids are not converted to their CoA derivatives and are not reesterified to 2-monoacylglycerol. Instead they are released into the portal circulation, where they are carried by serum albumin to the liverShort and Medium Chain Fatty Acids
The protein onto which fatty acids and fat soluble vitamins are loaded ontoApoliporotein B-48 (APO B-48)
Apoliprotein B-48 combined with phospholipids, triacylglycerol, cholesteryl ester and fat-soluble vitaminsChyomicron
Presence of excess fat in feces. Stools having oily appearance, difficult to flush and foul smellingSteatorrhoea

Fatty Acid Biosynthesis

Question Answer
Dietary carbohydrates and proteins in excess of body’s needs can be converted to fatty acids which are stored asTriacylglycerol
Process that occurs mainly in the liver, lactating mammary glands and, to a lesser extent, in adipose tissueFatty Acid Synthesis
Citrate which moves out of mitochondria byCitrate Transporter
Enzyme that releases acetyl CoA into the cytoplasmCitrate Lyase
Malate is converted to pyruvate using NADP+ as a coenzyme to produce NADPH plus H+Malic Enzyme
The rate limiting enzyme of fatty acid synthesis isAcetly CoA Carboxylase
The third carbon of Malonyl CoA comes fromCarbon Dioxide
Allosterically activates Acetyl CoA CarboxylaseCitrate
Allosterically inhibits Acetyl CoA CarboxylasePalmitoyl CoA
Under fasting conditions, glucagon, via protein kinase A, phosphorylates and inactivatesAcetyl CoA Carboxylase
Under well fed conditions, insulin activatesAcetyl CoA Carboxylase

Fatty Acid Synthase Complex

Question Answer
The final two carbons in Fatty Acid synthesis come fromAcetyl CoA
The rest of the carbons in Fatty Acid synthesis come fromMalonyl CoA
Added to acetyl CoA by Acetyl CoA Carboxylase to change acetyl CoA to malonyl CoA but does not contribute any carbons to the final Fatty Acid chainCarbon Dioxide
The most common placement of a double bond is between carbons 9 and 10 by ___________Δ9 Desaturase
Humans cannot make fatty acids with double bonds past the _______9th Carbon