5th Biochemistry Lecture Exam (Batch 2025) Flashcards
- Which enzyme when activated acts on diacylglycerol in the adipose cells?
A. Adipose triacylglycerol lipase
B. Hormone sensitive lipase
C. Monoacyglycerol lipase
D. Colipase
B. Hormone sensitive lipase
- Which is the major pathway of the oxidation of fatty acids?
A. Mitochondrial beta
B. Alpha
C. Omega
D. Peroxisomal
A. Mitochondrial beta
- In which cells does beta oxidation of fatty acids DO NOT occur?
A. Liver cells
B. Muscle cells
C. Red blood cells
D. Cardiac cells
C. Red blood cells
- To which molecule are fatty acids attached when activated?
A. Carnitine
B. CoEnzyme A
C. CoEnzyme Q
D. Acyl Carrier protein
B. CoEnzyme A
- Equivalent to how many moles of ATP are hydrolyzed in the activation of fatty acids?
A. One
B. Two
C. Three
D. Four
B. Two
- Which is source of energy that drives the activation reaction of fatty acids to completion?
A. Acyl adenylate moiety
B. Released AMP
C. PPi
D. CoA
C. PPi
- Which protein transports the palmitoyl carnitine inside the matrix?
A. Tricarboxylate translocase
B. Monocarboxylate translocase
C. Dicarboxylate translocase
D. Carnitine acyl carnitine translocase
D. Carnitine acyl carnitine translocase
- Which reactions, in the order of occurrence, are carried out every time a two carbon moiety is removed from a fatty acid subjected to beta oxidation?
A. Cleavage, hydration, oxidation, oxidation
B. Oxidation cleavage, oxidation, hydration
C. Oxidation, hydration, oxidation, cleavage
D. Hydration, oxidation, cleavage, oxidation
C. Oxidation, hydration, oxidation, cleavage
- To which complex of the ETC accepts are the electrons and protons released from the first oxidation reaction of beta oxidation?
A. NADH-CoQ oxidoreductase
B. ETFP-CoQ oxidoreductase
C. Cytochrome c oxidase
D. Cytochrome oxidase
B. ETFP-CoQ oxidoreductase
- Which enzyme catalyzes the 2nd reaction of beta oxidation?
A. 3-L-hydroxyacylCoA dehydrogenase
B. Acyl CoA dehydrogenase
C. Thiolase
D. Enoly CoA hydratase
D. Enoly CoA hydratase
- How many ATPs does the first reaction of beta oxidation generates after transferring its electrons and protons to the respiratory chain?
A. Two
B. Three
C. Four
D. Five
A. Two
- How many cycles/spirals would a 18
carbon saturated fatty acid undergo in beta oxidation releasing the acetyl CoA moieties?
A. Five
B. Six
C. Seven
D. Eight
D. Eight
- How many ATPs are generated from all the acetyl CoA moieties released from beta-oxidation of stearic acid?
A. 90
B. 102
C. 108
D. 118
C. 108
- What is another product of beta-oxidation of a 19 carbon saturated fatty acid aside from acetyl CoA?
A. Acetyl CoA
B. Isobutyryl CoA
C. Propionyl CoA
D. Valeryl CoA
C. Propionyl CoA
- To which intermediate of the Kreb’s cycle does the product of the last cycle/spiral of beta-oxidation of a 15 carbon fatty acid enter?
A. Fumarate
B. Succinyl CoA
C. Succinate
D. Malate
B. Succinyl CoA
16.Which additional enzyme is used in the beta oxidation of a monounsaturated fatty acid?
A. Δ3Δ2-enoyl CoA isomerase
B. 2,4-dienoyl CoA-reductase
C. Enoyl CoA-reductase
D. Acyl CoA dehydrogenase
A. Δ3Δ2-enoyl CoA isomerase
- How many ATP less would be derived from oxidation of a monounsaturated fatty acid compare with the oxidation of a saturated fatty acid having the same number of carbons?
A. Four
B. Three
C. Two
D. One
C. Two
- Which oxidation process is used to degrade very long chain fatty acids?
A. Mitochondrial beta
B. Alpha
C. Omega
D. Peroxisomal
D. Peroxisomal
- How would the products of oxidation of VLCFA generate energy in the form of ATP?
A. Have to be transported to the mitochondrial matrix
B. Thru the glycolytic pathway
C. Metabolized thru the alpha oxidation
D. Degraded via the omega oxidation
A. Have to be transported to the mitochondrial matrix
- More ATPs are formed per cycle/spiral thru mitochondrial beta oxidation than thru oxidation of VLCFA, by how many?
A. One
B. Two
C. Three
D. Four
B. Two
- Which enzyme catalyzes the rate-
limiting step of beta oxidation of palmitic acid?
A. Carnitine palmitoyl transferase I
B. Carnitine palmitoyl transferase II
C. Acetyl CoA carboxylase
D. Carnitine acyl-carnitine translocase
A. Carnitine palmitoyl transferase I
- To which does the FADH2, generated in the first oxidation step of peroxisomal oxidation, transfers its electrons and protons?
A. Complex II
B. ETFP-CoQ oxidoreductase
C. Oxygen
D. Complex I
D. Complex I
- Which is the product of peroxisomal oxidation of VLCFA?
A. Acetyl CoA
B. Propionyl CoA
C. Fatty dicarboxylyl CoA
D. Octanoyl CoA
D. Octanoyl CoA
- Which coenzyme is used in the oxidation steps of omega oxidation of fatty acids?
A. NAD+
B. NADH + H+ C. NADP+
D. NADPH + H+
A. NAD+
- Which enzyme is activated by cortisol in times of energy need?
A. Colipase
B. Desnutrin
C. Hormone sensitive lipase
D. Monoacylglycerol lipase
B. Desnutrin
- The chemical formula for AA is:
A. C20H32O2, 20:4(ω3)
B. C20H32O2, 20:4(ω6)
C. C20H32O2, 20:4(ω9)
D. C18H28O2, 20:4(ω3)
B. C20H32O2, 20:4(ω6)
- Significant precursors of eicosanoids include the following, except?
A. 5-8-11,14 - eicosatetraenoic acid
B. 8,11,14 - eicosatetraenoic acid
C. 5,8,1,14,17 - eicosapentaenoic acid
D. 6,9,11,14,17 - eicosapentaenoic acid
D. 6,9,11,14,17 - eicosapentaenoic acid
- Endogenous sources of arachidonic acid?
A. Linoleic acid
B. Dihomo-g-Linolenic acid
C. Oleic acid
D. N-Arachidonoyl
D. N-Arachidonoyl
- Arachidonic acid is most abundant in?
A. Liver
B. Lymphocytes
C. Platelets
D. Bone marrow
A. Liver
- Yields arachidonic acid from phospholipids by hydrolysis of the sn-2 position in one single step?
A. Phospholipase A1
B. Phospholipase A2
C. Phospholipase C
D. Phospholipase D
B. Phospholipase A2
- Requirement for activation and expression of phospholipases, as a response from cellular activation signals?
A. G coupled transducing protein
B. Toll-like receptor 4
C. Purinergic receptors
D. Tumor promoting agents
A. G coupled transducing protein
- Non-enzymatic reactions of arachidonic acid include which of the following?
A. Production of PGH2 by prostaglandin synthase.
B. Production of nitroeicosatetranoic acid by CCL4.
C. Production of LTA4 by 5-lipoxygenase.
D. Production of epoxyeicosatrienoic acid by epoxygenase.
B. Production of nitroeicosatetranoic acid by CCL4.
- Which following statement is false regarding cell to cell interactions in eicosanoid biosynthesis?
A. AA metabolism are usually similar from cell to cell and from tissue to another.
B. There is variability in enzyme expression depending on the state of the cell.
C. Unstable intermediates are transferred to another cell to trigger biosynthesis.
D. In an injured tissue, at least two cells must contain the complete enzyme cassette.
A. AA metabolism are usually similar from cell to cell and from tissue to another.
- Contributes to eicosanoids production and acts in a paracrine manner, propagates and amplifies inflammatory response to neighboring cells?
A. Cytosolic calcium dependent phospholipase A2
B. Secretory phospholipase A2
C. Cytosolic calcium independent phospholipase A2
D. Specialized phospholipase A2
B. Secretory phospholipase A2
- The principal mediator of inflammation, mitogenesis and angiogenesis?
A. Cyclooxygenase-1
B. Cyclooxygenase-2
C. Cyclooxygenase-3 D. Lipoxygenase
B. Cyclooxygenase-2
- Responsible for cell to cell signaling, tissue homeostasis and cytoprotection?
A. Cyclooxygenase-1
B. Cyclooxygenase-2
C. Cyclooxygenase-3
D. Lipoxygenase
A. Cyclooxygenase-1
- The 1st product of COX which is an unstable compound that quickly converts to PGH2?
A. Cyclic 8,10 endoperoxide, 15 hydroperoxide compound
B. Cyclic 6, 8 endoperoxide, 15 hydroperoxide compound
C. Cyclic 9, 11 endoperoxide, 15 hydroperoxide compound
D. Cyclic 6, 11 endoperoxide, 15 hydroperoxide compound
C. Cyclic 9, 11 endoperoxide, 15 hydroperoxide compound
- Effector function by PGI2?
A. Recruit basophils and eosinophils
B. Bronchoconstriction
C. Vasoconstriction
D. Uterine contraction
D. Uterine contraction
- TXA2 is converted from PGH2 by?
A. Thromboxane synthase
B. PGI2 synthase
C. Endoperoxide-D isomerase
D. Reductase
A. Thromboxane synthase
- The structural characteristics of PGI2 is similar to other prostaglandins, except?
A. Presence of a 5-member ring.
B. Presence of hydroxyl group C. Presence of double bonds
D. Arrangement of carbonyl group
D. Arrangement of carbonyl group
- Action of a prostacyclin synthase enzyme on PGH2 yield?
A. PGI2
B. PGD2
C. PGE2
D. TXA2
A. PGI2
- PGH2 conversion by endoperoxide-D isomerase and succeeding preferential conversion to 9-α,11-β-prostaglandin F will yield a product that will induce?
A. Hypertension from histamine release
B. Inhibition of platelet aggregation
C. Dilatation of vascular smooth muscle.
D. Bronchial dilatation
B. Inhibition of platelet aggregation
- The following statements are true of Prostaglandin E2, except?
A. Found in the gastric mucosa, renal medulla, microvascular endothelium and tumors.
B. Preserve the integrity of the gastric mucosa
C. Relaxation of bronchial smooth muscle tissues
D. Production results in unopposed vasoconstriction
D. Production results in unopposed vasoconstriction
- Which of the following statements of Thromboxane A2 is correct?
A. Include a 5-member ring containing an ether.
B. Has a different affinity for each eicosanoid-specific ligands.
C. Converted from PGH2 by thromboxane isomerase.
D. COX inhibition by aspirin results in complete loss of platelet function.
B. Has a different affinity for each eicosanoid-specific ligands.
- Which of the following statements is true of the relationship of COX expression and platelet function?
A. Platelets are unique in that they do not regenerate COX.
B. Promoters of platelet function are dependent on TXA2.
C. Aspirin inhibition of platelets completely alters its response.
D. TXA2 is not necessary for normal platelet function.
A. Platelets are unique in that they do not regenerate COX.
- Free arachidonic acid, to produce hydroperoxyeicosatetraenoic acid are acted upon by lipoxygenase enzymes. Which of the following is incorrect?
A. Oxygenation occurs at different Arachidonic acid positions.
B. 2 oxygen atoms are introduced ar C-5, C-8, C-9, or C-15.
C. Lipoxygenase enzymes are numbered according to the O2 introduced to the carbon atom.
D. Products include leukotrienes and lipoxins.
B. 2 oxygen atoms are introduced ar C-5, C-8, C-9, or C-15.
- Leukotriene A4 is produced from 5-hydroperoxyeicosatetraenoic acid by?
A. 5-LOX
B. 12-LOX
C. 15-LOX
D. LT synthase
D. LT synthase
- One enzyme that exerts its action on LTA4, whose product functions is chemotaxis and degranulation of PMNs?
A. LTA4 hydrolase
B. Glutathione transferase
C. Lipoxygenase
D. Glutathione isomerase
A. LTA4 hydrolase
- LTC4 is produced from LTA4 by?
A. H2O donating diol.
B. Adding glutathione molecules.
C. Adding amino acids.
D. O2 at carbon atoms.
B. Adding glutathione molecules.
- Involved in asthma and anaphylaxis?
A. LTA4
B. LTB4
C. LTC4
D. Lipoxins
C. LTC4
- Which of the following statements regarding fatty acid synthesis is/are FALSE?
A. It takes place in the mitochondrial matrix
B. Synthesis intermediates are covalently linked to Acyl Carrier Protein
C. Its rate-limiting enzyme is Acetyl-CoA carboylase
D. All of the above
A. It takes place in the mitochondrial matrix
- What are the four repeating steps in fatty acid synthesis in correct order (from most oxidized to least oxidized substrate)?
A. Condensation, reduction, dehydration, reduction
B. Oxidation, Hydration, oxidation, lysis
C. Reduction, dehydration, reduction, dehydration
D. Condensation, dehydration, reduction, condensation
A. Condensation, reduction, dehydration, reduction
- Which of the following acts as a source of reducing equivalents for fatty acid synthesis?
A. NADH
B. NADPH
C. Glutathione peroxidise
D. Fatty acid synthase
B. NADPH
- Fatty acid synthesis is synthesized __ carbon(s) at a time for each cycle with the final product being ___.
A. 4, Oleic acid
B. 1, Acetoacetyl-CoA
C. 2, Palmitic acid
D. 8, Palmitate
C. 2, Palmitic acid
- Which carbon(s) is/are initially added to the structure of a fatty acid?
A. Methyl end carbon
B. Carboxyl end carbon
C. Unsaturated carbons
D. Chiral carbon
A. Methyl end carbon
- Which of the following activates Fatty acid synthesis?
A. Insulin
B. Citrate
C. Long-chain Fatty Acyl-CoA
D. A and B only
D. A and B only
- The rate-limiting enzyme of fatty acid synthesis is inhibited by:
A. Cyclic AMP
B. Dephosphorylation
C. Insulin
D. All of the above
A. Cyclic AMP
- Fatty acid synthesis from its 2-carbon Co-A precursor needs to be transferred to the cytosol from the mitochondria. This is done by converting the precursor to
________.
A. Malate
B. Citrate
C. Oxaloacetate
D. Acetoacetyl-CoA
B. Citrate
- The rate-limiting enzyme of fatty acid synthesis is activated by ______ and switched off by ________.
A. Phosphorylation, dephosphorylation
B. Dephosphorylation, phosphorylation
C. Acetylation, deacetylation
D. Deacetylation, acetylation
B. Dephosphorylation, phosphorylation
- The rate-limiting enzyme of fatty acid synthesis uses this as a carbon dioxide carrier:
A. Biotin
B. Pyridoxine
C. NADPH
D. Folate
A. Biotin
- Conversion of malate to oxaloacetate:
A. PENTOSE PHOSPHATE PATHWAY
B. CITRIC ACID CYCLE
C. PYRUVATE DEHYDROGENASE COMPLEX
D. FATTY ACID SYNTHASE COMPLEX
E. ACETYL-COA-CARBOYXLASE
B. CITRIC ACID CYCLE
- Formation of Acetyl-CoA from glucose:
A. PENTOSE PHOSPHATE PATHWAY
B. CITRIC ACID CYCLE
C. PYRUVATE DEHYDROGENASE COMPLEX
D. FATTY ACID SYNTHASE COMPLEX
E. ACETYL-COA-CARBOYXLASE
C. PYRUVATE DEHYDROGENASE COMPLEX
- Main source of reducing equivalents for fatty acid synthesis:
A. PENTOSE PHOSPHATE PATHWAY
B. CITRIC ACID CYCLE
C. PYRUVATE DEHYDROGENASE COMPLEX
D. FATTY ACID SYNTHASE COMPLEX
E. ACETYL-COA-CARBOYXLASE
A. PENTOSE PHOSPHATE PATHWAY
- Enoyl reductase:
A. PENTOSE PHOSPHATE PATHWAY
B. CITRIC ACID CYCLE
C. PYRUVATE DEHYDROGENASE COMPLEX
D. FATTY ACID SYNTHASE COMPLEX
E. ACETYL-COA-CARBOYXLASE
D. FATTY ACID SYNTHASE COMPLEX
- Production of Malonyl-CoA:
A. PENTOSE PHOSPHATE PATHWAY
B. CITRIC ACID CYCLE
C. PYRUVATE DEHYDROGENASE COMPLEX
D. FATTY ACID SYNTHASE COMPLEX
E. ACETYL-COA-CARBOYXLASE
E. ACETYL-COA-CARBOYXLASE
- Complex amino alcohol plus fatty acid, which is abundant in cell membranes that are specialized to form lipid rafts:
A. TRIACYLGLYCEROL
B. GLYCEROPHOSPHOLIPIDS
C. ETHER GLYCEROLIPIDS
D. SPHINGOMYELIN
E. GLYCOLIPIDS
D. SPHINGOMYELIN
- Mostly stored as energy reserve in adipose tissue and liver:
A. TRIACYLGLYCEROL
B. GLYCEROPHOSPHOLIPIDS
C. ETHER GLYCEROLIPIDS
D. SPHINGOMYELIN
E. GLYCOLIPIDS
A. TRIACYLGLYCEROL
- Cerebrosides and globosides:
A. TRIACYLGLYCEROL
B. GLYCEROPHOSPHOLIPIDS
C. ETHER GLYCEROLIPIDS
D. SPHINGOMYELIN
E. GLYCOLIPIDS
E. GLYCOLIPIDS
- Plasmalogens:
A. TRIACYLGLYCEROL
B. GLYCEROPHOSPHOLIPIDS
C. ETHER GLYCEROLIPIDS
D. SPHINGOMYELIN
E. GLYCOLIPIDS
C. ETHER GLYCEROLIPIDS
- Lung surfactant:
A. TRIACYLGLYCEROL
B. GLYCEROPHOSPHOLIPIDS
C. ETHER GLYCEROLIPIDS
D. SPHINGOMYELIN
E. GLYCOLIPIDS
B. GLYCEROPHOSPHOLIPIDS
- Which of the following is the initial substrate used for fatty acid synthesis?
A. Pyruvate
B. Lactate
C. Succinyl-CoA
D. Acetyl-CoA
D. Acetyl-CoA
- Which of the following activates fatty acid synthesis?
A. Palmitoyl-CoA
B. Malonyl-CoA
C. Citrate
D. Oxaloacetate
C. Citrate
- What do you call the bond between glycerol and a fatty acid?
A. Hydrogen
B. Ionic
C. Ether
D. Ester
D. Ester
- Which of the following regulates fatty acid transport?
A. Palmitoyl
B. Malic enzyme
C. Carnitine
D. ATP: Citrate Lyase
C. Carnitine
- Which of the following hormones activate hormone-sensitive lipase?
A. Insulin
B. Glucagon
C. Phosphodiesterase
D. Prostaglandin A2
B. Glucagon
- Cholesterol is transported via:
A. Phospholipids
B. Lipoproteins
C. Phosphoproteins
D. Sphingolipids
B. Lipoproteins
- Cholesterol is the precursor for the following except:
A. Sex hormones
B. Vitamin D
C. Vitamin A
D. Bile acids
C. Vitamin A
- Synthesis of cholesterol occurs in the cytosol and in:
A. Golgi apparatus
B. Lysosome
C. Endoplasmic reticulum
D. Mitochondria
C. Endoplasmic reticulum
- Free cholesterol is removed from tissues and transported to the liver by:
A. Chylomicrons
B. HDL
C. LDL
D. VLDL
B. HDL
- The enzyme that catalyzes the rate-limiting step in cholesterol synthesis:
A. Thiolase
B. HMG CoA synthase
C. HMG CoA reductase
D. Isomerase
C. HMG CoA reductase
- Cholesterol is synthesized in:
A. Liver and intestines only
B. RBCs only
C. All nucleated cells
D. A and B only
C. All nucleated cells
- The structure of cholesterol is a cyclopentano___ phenanthrene ring
A. Dihydro
B. Perhydro
C. Pentahydro
D. Cyclohydro
B. Perhydro
- In cholesterol structure, the hydroxyl group is located at the:
A. C3
B. C5
C. C6
D. C17
A. C3
- The storage form of cholesterol:
A. Cholesteryl ester
B. Free cholesterol
C. Fatty acid
D. Sterols
Cholesteryl ester
- The formation of isoprenoid units from mevalonate requires how many ATP?
A. None
B. 1
C. 2
D. 3
D. 3
- HMG-CoA is a _____ compound:
A. 5-carbon
B. 6-carbon
C. 10-carbon
D. 15-carbon
B. 6-carbon
- The source of all carbon atoms in cholesterol:
A. ATP
B. Glucose-6-PO4
C. Acetyl CoA
D. Propionyl CoA
C. Acetyl CoA
- HMG CoA reductase is active in the:
A. Phosphorylated form
B. Dephosphorylated form
C. Both
D. None
B. Dephosphorylated form
- Which hormone/s downregulates the expression of the gene for HMG CoA reductase?
A. Insulin
B. Glucagon
C. Thyroxine
D. A and C
B. Glucagon
- The statin drugs are structural analogs of HMG CoA and are ____ inhibitors of HMG CoA reductase
A. Nonreversible, competitive
B. Reversible, competitive
C. Reversible, noncompetitive
D. Nonreversible, noncompetitive
B. Reversible, competitive
- This lipoprotein contains the highest TAG:
A. LDL
B. HDL
C. VLDL
D. Chylomicrons
D. Chylomicrons
- LDL is taken up by the cell via:
A. Transport protein
B. Endocytosis
C. Ligand channel
D. Proton pump
B. Endocytosis
- True of cholesterol excretion except:
A. Small percentage excreted in the feces
B. Converted to bile acid and bile salts
C. Cholesterol is metabolized to CO2 and H2O
D. none
C. Cholesterol is metabolized to CO2 and H2O
- 7α-hydroxylation of cholesterol requires NADPH, cytochrome P450 and ______
A. Cu
B. Vitamin
C. Oxygen
D. Zn
C. Oxygen
- Conjugation of bile acids with taurine or glycine takes place in the:
A. Cytosol
B. Mitochondria
C. Peroxisomes
D. Endosomes
C. Peroxisomes
- Secondary bile acids are formed by:
A. Conjugation
B. Hydroxylation
C. Intestinal bacteria activity
D. Salting out
C. Intestinal bacteria activity
- The rate limiting step in synthesis of steroids from cholesterol is catalyzed by:
A. Hydroxylase
B. Reductase
C. Desmolase
D. Isomerase
C. Desmolase
- The parent compound for all steroid hormones:
A. Pregnenolone
B. Progesterone
C. Testosterone
D. Estrogen
A. Pregnenolone
- Testosterone is converted to estrogen
by:
A. Reductase
B. Dehydrogenase
C. Aromatase
D. Angiotensinogen
C. Aromatase
- The principal sterol in the feces is:
A. Cholic acid
B. Chenodeoxycolic acid
C. Glycine
D. Coprostanol
D. Coprostanol
