UNE BIOCHEM FINAL
Which of the following compounds or substrates is required for the synthesis of tyrosine? (+ indicates the compound is required; - indicates the compound is not required)
-tetrahydrofolate (THF), +tetrahydrobiopterin (BH4), -tryptophan, +phenalanine
A deficiency in vitamin B6 (pyridoxal phosphate) would negatively impact which of the following pathways: 1-Metabolism of cysteine to homocysteine 2-Metabolism of phenylalanine to tyrosine 3-Conversion of methyl malonyl-Co A to succinyl-CoA 1 only 2 only 2 and 3 1 and 2
1 only
An increase in the ratio of insulin to glucagon will increase the activity of which of the following enzymes (+ indicates activity is increased; - indicates activity is not increased by insulin)?
4 -Hormone-sensitive lipase +Acetyl-CoA carboxylase +Phosphofructokinase 2 (PFK2) +Glycogen synthase When insulin is elevated fed state pathways will be persistent. This will include the activation of acetyl-CoA carboxylase through dephosphorylation. PFK2 in glycolysis and glucagon synthase will also be active under these conditions.
A 3-year-old male is brought to the emergency department with hypoglycemia following a brief seizure. His parents put him to bed the night before and he had not eaten much dinner. His urine tested positive for dicarboxylic acids, serum-free fatty acids are elevated and there were no detectable ketones in his blood or urine. In this individual, at the time of presentation his ratio of insulin to glucagon is: 1 >1 <1
<1
A deficiency in which of the following proteins will reduce cholesterol efflux from peripheral tissues to HDL particles? Carnitine palmitoyl transferase I (CPTI) ApoB100 ABCG1 CETP (Cholesteryl ester transfer protein)
ABCG1
Glucogenic amino acids can be used in the process of gluconeogenesis and will be metabolized to all of the following compounds except: Fumarate Oxaloacetate Succinyl-CoA Acetyl-CoA
Acetyl-CoA
Glucogenic amino acids can be used in the process of gluconeogenesis and will be metabolized to all of the following compounds except: Succinyl-CoA Fumarate Oxaloacetate Acetyl-CoA
Acetyl-CoA
When citrate is shuttled out of the mitochondria for fatty acid synthesis, the initial reaction by citrate lyase generates which of the following products? Acetyl-CoA and citrate Citrate and oxaloacetate Acetyl-CoA and oxaloacetate Pyruvate and malate
Acetyl-CoA and oxaloacetate
When citrate is shuttled out of the mitochondria for fatty acid synthesis, the initial reaction by citrate lyase generates which of the following products? Citrate and oxaloacetate Acetyl-CoA and citrate Acetyl-CoA and oxaloacetate Pyruvate and malate
Acetyl-CoA and oxaloacetate
In the case of a deficiency of biotin, which of the following enzymes required for fatty acid metabolism will be impaired? Pyruvate dehydrogenase complex Carnitine palmitoyl transferase I Fatty acid synthase Acetyl-CoA carboxylase
Acetyl-CoA carboxylase
fatty acid synthase is a multimeric enzyme complex. Which of the following subunits contains pantothenic acid as a cofactor? Ketoacyl synthase Enoyl reductase Acyl carrier protein (ACP) Thioesterase
Acyl carrier protein (ACP)
Defects in the urea cycle directly impair the use of which of the following substrates for gluconeogenesis? Fatty acids Amino acids Lactate Glycerol
Amino acids
A 12-year-old male is brought to his primary care physician. His parents are concerned with his recent decline in school work due to persistent blurred vision. On physical exam, planar xanthomas are noted and laboratory testing reveals extremely low plasma HDL. This presentation would be consistent with a loss of which of the following apoproteins? ApoA ApoB48 ApoB100 ApoE
ApoA
Which of the following urea cycle enzymes catalyzes the reaction hydrolyzing the release of urea from arginine? Ornithine transcarbamoylase Argininosuccinate lyase N-acetyl glutamate synthetase Arginase
Arginase
Which of the following amino acids has a nitrogen in its side chain (R-group) and is an intermediate of the urea cycle? Arginine Asparagine Glutamate Methionine Phenylalanine
Arginine
A 10-year-old female presents with chest pain and xanthomas over her elbows and knees. Her father died of a heart attack at age 35. Her mother has high cholesterol. Her physician suspects heterozygous familial hypercholesterolemia in the parents with the homozygous disease presentation in the daughter. This disease results from mutations in the receptor for low-density lipoprotein (LDL) or the ligand portion of its apoprotein coat. Which of the following apoproteins might be mutated? AI B100 B48 CII E
B100
Which of the following enzymes is regulated by N-acetyl glutamate (NAG)? Carbamoyl phosphate synthetase II (CPS II) Ornithine transcarbamylase Argininosuccinate lyase Carbamoyl phosphate synthetase I (CPS I)
Carbamoyl phosphate synthetase I (CPS I)
Which of the following enzymes is the regulatory step in the urea cycle? Argininosuccinate lyase Arginase Carbamoyl phosphate synthetase I (CPS I) Ornithine transcarbamylase
Carbamoyl phosphate synthetase I (CPS I)
In the liver, which of the following key inhibitory events ensures that newly synthesized palmitoyl-CoA is not immediately oxidized? Carnitine palmitoyl transferase-I (CPTI) by palmitoylcarnitine Carnitine palmitoyl transferase-II (CPTII) by acetyl-CoA Acyl-CoA synthetase by malonyl CoA Carnitine palmitoyl transferase-I (CPTI) by malonyl-CoA Carnitine acylcarnitine translocase (CAT) by palmitoyl-CoA
Carnitine palmitoyl transferase-I (CPTI) by malonyl-CoA Malonyl-CoA produced in the cytosol as part of fatty acid synthesis will inhibit the transport of fatty acids across the mitochondrial membrane such that fatty acid synthesis is not occurring at the same time as β-oxidation
Which of the following compounds is the primary component of a mature HDL? Glycerol Cholesteryl-ester Cholesterol Fatty acids Triacylglycerol
Cholesteryl-ester
In the reaction catalyzed by cholesteryl ester transfer protein (CETP), the VLDL particle receives which of the following compounds from HDL particles? Free fatty acids Cholesteryl-ester Triacylglycerol Bile salts
Cholesteryl-ester Explain how VLDL is metabolized by lipases to intermediate-density lipoprotein (IDL) which may be cleared by the liver or converted to low-density lipoprotein (LDL), which functions to deliver cholesterol from the liver to extrahepatic tissues via the LDL (apoB100, E) receptor.
In the salvage of purines, hypoxanthine-guanine phosphoribosyltransferase (HGPRT) is responsible for which of the following processes? Conversion of hypoxanthine to xanthine Conversion of guanine to guanosine monophosphate (GMP) Conversion of adenine to adenosine monophosphate (AMP) Conversion of inosine monophosphate to inosine
Conversion of guanine to guanosine monophosphate (GMP)
A 17-year-old female is diagnosed with a vitamin B12 (cobalamin) deficiency. In this individual, which of the following reactions would be compromised? Conversion of methionine to S-adenosyl homocysteine Conversion of betaine to methionine Conversion of methyl malonyl-Co A to succinyl-CoA Conversion of homocysteine to cysteine
Conversion of methyl malonyl-Co A to succinyl-CoA
Insulin stimulates lipogenesis through several mechanisms. Which of the following is not an insulin-stimulated process that enhances lipogenesis? Decreased levels of cAMP Increased activity of acetyl-CoA carboxylase Increased glucose transport into the cells Decreased activity of the pyruvate dehydrogenase complex
Decreased activity of the pyruvate dehydrogenase complex Insulin will stimulate the activity of the PDC, acetyl-CoA carboxylase, and glucose transport into cells. It will also decrease levels of cAMP by decreasing signaling through glucagon.
A 47-year-old male is prescribed a statin (HMG-CoA reductase inhibitor) to manage his elevated LDL cholesterol. What is the direct mechanism of action of this drug? Stimulating synthesis of LDL receptors Stimulating hepatic synthesis of bile acids from cholesterol Stimulating hepatic synthesis of esterified cholesterol Decreasing hepatic cholesterol biosynthesis Decreasing intestinal absorption of dietary cholestero
Decreasing hepatic cholesterol biosynthesis
After an overnight fast, which of the following compounds would be elevated in the blood of a patient with primary carnitine deficiency? β-hydroxybutyrate Acetoacetate Fatty acids Glucose
Fatty acids
Under fasting conditions, acetyl-CoA carboxylase will be inhibited by an increase in which of the following compounds? Fatty acyl-CoA Malonyl CoA Glucose Citrate
Fatty acyl-CoA
Under fasting conditions, acetyl-CoA carboxylase will be inhibited by an increase in which of the following compounds? Glucose Fatty acyl-CoA Malonyl CoA Citrate
Fatty acyl-CoA
An individual goes to bed around 8 pm and doesn't wake up until 9 am the next morning. During this time, which of the following is the primary oxidizable substrate for skeletal muscle? Free fatty acids Glycogen Lactate Amino acids
Free fatty acids
An individual goes to bed around 8 pm and doesn't wake up until 9 am the next morning. During this time, which of the following is the primary oxidizable substrate for skeletal muscle? Lactate Free fatty acids Glycogen Amino acids
Free fatty acids Under fasted conditions as described above the skeletal muscle and liver would be oxidizing free fatty acids as a means of producing ATP.
A 22-year-old female goes on a hunger strike on a prominent corner in a city park. She refuses all offers of food except for water through the first 2 weeks. Under these conditions, there is a decreased reliance on which of the following pathways for fuel? Ketogenesis Lipolysis β-oxidation Gluconeogenesis
Gluconeogenesis
A 22-year-old female goes on a hunger strike on a prominent corner in a city park. She refuses all offers of food except for water through the first 2 weeks. Under these conditions, there is a decreased reliance on which of the following pathways for fuel? Gluconeogenesis β-oxidation Lipolysis Ketogenesis
Gluconeogenesis Under conditions of excess fasting (i.e. starvation) the brain will begin to oxidize ketones as a primary fuel source reducing its reliance on glucose
alph aketogulterate is to oxaloacetate as aspartate is to ____ (reactioncatalyzed by AST)
Glutamate
Two hikers get lost in the woods, they have not brought any snacks or water with them. As time passes their insulin to glucagon ratio decreases. 24 hours into their fast you would expect the enzymatic activity of both _________ and ________ to be elevated in the liver. Glutaminase and carbamoyl phosphate synthetase I Glycogen synthase and carnitine palmitoyltransferase I PEP carboxykinase (PEPCK) and pyruvate kinase Glutamine synthase and Phosphofructokinase 2 (PFK2)
Glutaminase and carbamoyl phosphate synthetase I
Which of the following best describes the role of HDL particles? HDLs are required for the transport of dietary cholesterol to the liver HDLs are required for transporting cholesterol from the liver to the peripheral tissues HDL particles are required for the transport of cholesterol from peripheral tissues to the liver HDLs transport triacylglycerol from the liver to the adipose
HDL particles are required for the transport of cholesterol from peripheral tissues to the liver
Which of the following is the regulatory enzyme in cholesterol synthesis? Carnitine palmitoyl transferase I (CPTI) Acetyl CoA carboxylase HMG-CoA synthase HMG-CoA reductase
HMG-CoA reductase
Several familial disorders are characteristic of defects in the LDL-receptor that inhibit cellular uptake of LDLs and reduce intracellular cholesterol. In these patients, all of the following are true except: HMG-CoA - reductase is activated HMG-CoA reductase is phosphorylated Circulating levels of LDL are elevated SREBP is cleaved and activated
HMG-CoA reductase is phosphorylated
Which of the following lipoproteins would be the largest contributors to a measurement of plasma cholesterol in an individual following a 12 hr. fast? LDLs and adipocyte lipid droplets Chylomicron remnants and very-low-density-lipoproteins (VLDLs) Chylomicrons and VLDLs High-density lipoproteins (HDLs) and LDLs VLDLs and LDLs
High-density lipoproteins (HDLs) and LDLs Explain how VLDL is metabolized by lipases to intermediate-density lipoprotein (IDL) which may be cleared by the liver or converted to low-density lipoprotein (LDL), which functions to deliver cholesterol from the liver to extrahepatic tissues via the LDL (apoB100, E) receptor.
Cobalamin supplementation would be most appropriate in the case of which of the following enzyme deficiencies? Cystathionine β-synthase Branched-chain keto-acid dehydrogenase Phenylalanine hydroxylase Homocysteine methyltransferase
Homocysteine methyltransferase
A 5-year-old female is brought to the emergency department by her mother. She is a type 1 diabetic and has not taken her insulin while away at a day camp. The child is unresponsive. Which of the following enzymes is phosphorylated and active under these conditions? Acetyl-coA carboxylase Hormone sensitive lipase Glycogen synthase Phosphofructokinase 2 Pyruvate kinase
Hormone sensitive lipase
What is the role of adipose in metabolism?
In the feeding state, insulin-dependent glucose transport 4 (GLUT 4) allows the uptake of glucose from the bloodstream to adipocytes. Glycolysis occurs, producing glycerol-3-phosphate (glycerol-3-P), a substrate required for lipogenesis. Fatty acids from liver carried by very low-density lipoproteins (VLDL) and chylomicrons from the intestine are esterified with glycerol-3-P to form lipid droplets of triacylglycerols (TAGs). In the fasting state and in stress conditions, hormonesensitive lipase is activated for lipolysis. Some steps are required to produce glycerol, which travels to the liver, and fatty acids. These free fatty acids will tra vel in the bloodstream to the liver, muscle and to other organs to be oxidized. In the bloodstream fatty acids are immediately bound to albumin
Gout can present as a complication of von Gierke disease due to which of the following mechanisms? Increased DNA synthesis Increase synthesis of PRPP Decreased excretion of uric acid Decreased salvage of purines
Increase synthesis of PRPP
Ketogenesis is regulated by the rate of several other processes. Which of the following would decrease the rate of ketone body synthesis? Increased lipolysis Increased β-oxidation Increased flux through the TCA cycle. Increased transport of FFA across the mitochondrial membrane
Increased flux through the TCA cycle.
Mr. Smith has elevated cholesterol levels. He has heard that increasing the fiber in his diet may help control his cholesterol levels. Fiber lowers serum cholesterol levels by: Inhibiting pancreatic lipase Increasing bile acid excretion Inhibiting lipoprotein synthesis Decreasing bile acid synthesis
Increasing bile acid excretion
Elevated cholesterol can enhance bile acid synthesis through which of the following mechanisms? Inhibition of Cholesterol esterase Increasing activity of HMG-CoA Reductase Increasing the activity of 7 α-hydroxylase Inhibition of 12 α-hydroxylase
Increasing the activity of 7 α-hydroxylase
An elevation of purine nucleotides will negatively regulate pyrimidine synthesis through which of the following mechanisms?
Inhibiting the activity of carbamoyl phosphate synthetase II
Acetyl-CoA Carboxylase will be active when which of the following hormones is elevated? Epinephrine Cortisol Glucagon Insulin
Insulin
In the event of a deficiency in ApoCII on VLDLs, which of the following processes would be impaired? Interaction of VLDL with lipoprotein lipase Transfer of triacylglycerols from HDL to chylomicrons Reuptake of chylomicron remnants by the liver Uptake of chylomicrons by peripheral tissues using the LDL receptor
Interaction of VLDL with lipoprotein lipase
Nascent chylomicrons are synthesized in which of the following organs? Intestine Liver Kidney Blood
Intestine
A newborn becomes lethargic after several feedings and the assigned nurse describes an unusual smell to the urine. Evaluation for an inborn error of metabolism shows an elevation of branch-chain amino acids. Elevation of which of the following amino acids would be consistent with the report? Lysine Arginine Isoleucine Threonine Aspartic acid
Isoleucine
Phosphatidylcholine: cholesterol acyltransferase (PCAT, aka LCAT) is a plasma enzyme associated with HDL particles. Which of the following best describes its role in cholesterol transport? It is required for the movement of cholesterol out of the cell It esterifies cholesterol to trap it in HDL particles It is involved in the synthesis of cholesterol derivatives such as bile acids The enzyme is required for the degradation of cholesterol
It esterifies cholesterol to trap it in HDL particles Explain how high-density lipoprotein (HDL) is synthesized, indicate the mechanisms by which it accepts cholesterol from extrahepatic tissues, and returns it to the liver in reverse cholesterol transport.
During the fed state, high insulin to glucagon ratio inhibits the synthesis of: Glycogen Ketone bodies Protein Fatty acids
Ketone bodies
Which of the following is the major source of extracellular cholesterol for human tissues? LDLs γ-Globulin HDLs Albumin VLDLs
LDLs Explain how VLDL is metabolized by lipases to intermediate-density lipoprotein (IDL) which may be cleared by the liver or converted to low-density lipoprotein (LDL), which functions to deliver cholesterol from the liver to extrahepatic tissues via the LDL (apoB100, E) receptor. The primary role of LDL is to transport cholesterol to peripheral tissues. HDLs function in reverse cholesterol transport; VLDLs role is to carry newly synthesized triacylglycerols.
A defect in the thioesterase subunit of fatty acid synthase would impair which of the following activities of the enzyme complex? Liberation of newly assembled palmitate from the enzyme Liberation of CO2 from 3-ketoacyl synthase Priming of the enzyme with acetyl-CoA Binding of malonyl-CoA to an SH group
Liberation of newly assembled palmitate from the enzyme
A defect in the thioesterase subunit of fatty acid synthase would impair which of the following activities of the enzyme complex? Liberation of CO2 from 3-ketoacyl synthase Liberation of newly assembled palmitate from the enzyme Priming of the enzyme with acetyl-CoA Binding of malonyl-CoA to an SH group
Liberation of newly assembled palmitate from the enzyme Fatty acid synthase is a multimeric enzyme and the final and sixth enzyme in the chain is the thioesterase which will liberate the newly formed palmitate.
The enzyme that catalyzes the hydrolysis of triacylglycerol from chylomicrons and VLDL is: Lipoprotein lipase Hormone-sensitive lipase Phosphatidylcholine:cholesterol acyltransferase (PCAT, aka LCAT) HMG CoA reductase
Lipoprotein lipase Illustrate the structure of a lipoprotein particle. Indicate the major types of apolipoprotein found in the different lipoprotein classes. Explain that triacylglycerol from the diet is carried to the liver in chylomicrons and from the liver to extrahepatic tissues in very-low-density lipoprotein (VLDL), and that these particles are synthesized in intestinal and liver cells, respectively, by similar processes.Illustrate the processes by which chylomicrons are metabolized by lipases to form chylomicron remnants, which are then removed from the circulation by the liver.
Methotrexate is a potent anticancer agent that starves dividing cells of deoxyribonucleotides through direct inhibition of which of the following processes? Degradation of purine bases to uric acid Synthesis of purine bases Synthesis of thymidine Deoxygenation of the ribose ring to produce deoxyribose for DNA Metabolism of folic acid
Metabolism of folic acid Identify the reactions discussed that are inhibited by anticancer drugs. Explain why antifolate drugs and analogs of the amino acid glutamine inhibit purine biosynthesis.
A deficiency in which of the following enzymes would impair the production of S-adenosylmethionine (SAM)? Phenylalanine hydroxylase Tryptophan synthase Spermidine synthase Methionine adenosyltransferase (MAT)
Methionine adenosyltransferase (MAT)
A deficiency in which of the following enzymes will not result in an increase in orotic acid? Argininosuccinate synthetase Argininosuccinate lyase Ornithine transcarbamylase N-acetyl glutamate synthetase
N-acetyl glutamate synthetase
Which of the following enzymes is correctly paired with its activator? Glutaminase; citrate arginase; NADH Carbamoyl phosphate synthetase I; ATP N-acetyl glutamate synthetase; arginine
N-acetyl glutamate synthetase; arginine
What are the direct products of β-oxidation?
NADH, FADH2: Oxidized in the ETC to produce ATP (ATP is required for anabolic process in the fasted state! Gluconeogenesis Urea cycle) Acetyl-coa:Substrate for ketogenesis Allosterically activates pyruvate carboxylase
Malate can be converted to pyruvate in the cytosol. Which of the following compounds is directly generated in this conversion and is essential for fatty acid synthesis? ATP Acetyl-CoA FADH2 NADPH
NADPH
A deficiency in the ability to convert phenylalanine to tyrosine may result in a further deficiency of both _________________ and ________________. Norepinephrine and epinephrine Acetylcholine and choline Glutamine and glutamine Serotonin and melatonin Cysteine and homocysteine
Norepinephrine and epinephrine
A newborn is suspected of a defect in nucleotide synthesis due to the elevation of orotic acid. It is determined there is no deficiency in orotate phosphoribosyltransferase. Based on this presentation, which of the following enzymes is most likely deficient? Carbamoyl phosphate synthetase II (CPSII) Glutamyl amidotransferase Thymidylate synthase Ornithine transcarbamylase
Ornithine transcarbamylase
An comatose infant is brought to the emergency department. In the course of the examination, plasma ammonia was found to be elevated 20-fold over normal values. Urine orotic acid and uracil were both greater than normal. A defect of which of the following enzymes is the most likely diagnosis? Ornithine transcarbamylase Carbamoyl phosphate synthetase I N-acetyl glutamate synthetase Phosphoribosyl pyrophosphate synthetase (PRPP Synthetase) Carbamoyl phosphate synthetase II
Ornithine transcarbamylase
NADPH and glyceraldehyde 3-phosphate are essential for the synthesis of fatty acids and triacylglycerols. Which of the following pathways can supply both of these products? Pentose phosphate pathway Glycolysis Ketogenesis Fructose metabolism
Pentose phosphate pathway
In reverse cholesterol transport, HDL interacts with the ABCA1 transporter to move cholesterol from the cell to the HDL. This also requires the activity of which of the following enzymes? LDL receptor Lipoprotein lipase Phosphatidylcholine:cholesterol acyltransferase (PCAT, aka LCAT) Cholesteryl ester transfer protein (CETP)
Phosphatidylcholine:cholesterol acyltransferase (PCAT, aka LCAT)
What is the primary lipid component of a nascent HDL particle? Phospholipids Cholesteryl-ester Triacylglycerols Cholesterol
Phospholipids
What is the primary lipid component of a nascent HDL particle? Phospholipids Cholesterol Triacylglycerols Cholesteryl-ester
Phospholipids
in abetalipoproteinemia lipoproteins containing apoB are not formed and lipid droplets accumulate in the intestine and the liver. So in these individuals what is the level of plasma triglycerides and cholesterol?
Plasma triglycerides 24.5 mg/dL [normal < 150 mg/dL] Total cholesterol 5 mg/dL [ <200 mg/dL]
The LDL receptor is also highly regulated in the cell. Which of the following proteins targets the LDL receptor for degradation? AMPK kinase Proprotein convertase subtilisin/kexin type 9 (PSK9) Cholesterol esterase transfer protein (CETP) Acyl-CoA:cholesterol acyltransferase (ACAT)
Proprotein convertase subtilisin/kexin type 9 (PSK9) Explain that cholesterol balance in cells is tightly regulated and indicate the factors involved in maintaining the correct balance. PSK9 is a regulator of LDL receptor recycling. It targets the receptors for degradation rather than allowing them to be recycled to the cell surface.
Ubiquitination is a means of targeting a protein for which of the following cellular processes? Protein translation Digestion Proteasomal degradation Storage
Proteasomal degradation
Secondary bile salts lack a hydroxyl (OH) group when compared to primary bile salts. What is the consequence of the loss of this group? Secondary bile salts are more soluble The loss of the OH group does not change their functionality Secondary bile salts are less soluble Secondary bile salts are more readily resorbed in the intestinal lumen
Secondary bile salts are less soluble
The products of the oxidation of a fatty acid with an odd number of carbons will enter the TCA cycle as acetyl-CoA and: α-ketoglutarate Malate Citrate Succinyl CoA
Succinyl CoA
Which of the following best describes the primary role of bile salts during the digestive process? They are reabsorbed in the ileum They are digested by pancreatic lipase. They are packaged into chylomicrons They are used for the emulsification of dietary lipids.
They are used for the emulsification of dietary lipids.
Supplementation of which of the following cofactors/coenzymes may assist the activity of branched-chain ketoacid dehydrogenase? Pyridoxal phosphate (PLP) Cobalamin Folate Tetrahydrobiopterin (BH4) Thiamine
Thiamine
Which of the following enzymes used for ketone oxidation is not found in liver cells? HMG-CoA synthase Thiolase (acetyl-CoA C-acetyltransferase) Thiophorase (succinyl-CoA:acetoacetate transferase) β-hydroxybutyrate dehydrogenase
Thiophorase (succinyl-CoA:acetoacetate transferase)
Which of the following enzymes used for ketone oxidation is not found in liver cells? Thiolase (acetyl-CoA C-acetyltransferase) HMG-CoA synthase Thiophorase (succinyl-CoA:acetoacetate transferase) β-hydroxybutyrate dehydrogenase
Thiophorase (succinyl-CoA:acetoacetate transferase)
A 3-year-old male is brought to the emergency department by his parents. He is unconscious on admittance and his blood glucose was 15 mg/dl, ( normal 75 - 105 mg/dl). Further testing showed this individual had a deficiency in carnitine. Based on this diagnosis you would also expect which of the following to be true with regards to metabolism: This patient would have decreased levels of lipolysis. This patient would have increased activity of gluconeogenesis. This patient would have increased ketogenesis. This patient would have elevated levels of circulating free fatty acids.
This patient would have elevated levels of circulating free fatty acids.
Cholesterol is a substrate for the synthesis of all of the following compounds except: Bile salts Aldosterone Cortisol Thyroid Hormone
Thyroid Hormone Explain the importance of cholesterol as an essential structural component of cell membranes and as a precursor of all other steroids in the body, and indicate its pathologic role in cholesterol gallstone disease and atherosclerosis development.
Serotonin is synthesized from which of the following amino acids? Threonine Tyrosine Tryptophan Valine
Tryptophan
The incidence of coronary heart disease is most strongly influenced by the Type of cholesterol consumed Amount of fat consumed Amount of cholesterol consumed Type of fat consumed
Type of fat consumed
In an individual with a deficiency in the branched-chain ketoacid dehydrogenase complex, metabolism of which of the following amino acids would not likely be impaired? Valine Leucine Tyrosine Isoleucine
Tyrosine
A patient with an insulinoma has high circulating levels of insulin. This will result in a(n): Inhibition of lipoprotein lipase Upregulation of the gene for HMG-CoA reductase Downregulation of the gene for 7 α-hydroxylase Stimulation of intracellular hormone-sensitive lipase
Upregulation of the gene for HMG-CoA reductas
Which of the following is the common intermediate for pyrimidine synthesis? Uridine monophosphate (UMP) Cytidine monophosphate (CMP Inosine monophosphate (IMP) Hypoxanthine
Uridine monophosphate (UMP)
If you go to the Dr.'s office and have blood drawn for a lipid panel. Prior to the test you are asked to fast for 24 hours. In reviewing the results, which lipoprotein is most reflected by your blood levels of triacylglycerol? chylomicrons VLDL
VLDL
Which of the following enzymes is likely to be active in both the fed and fasted states? a) Glutaminase b) Pyruvate kinase c) Hormone sensitive lipase d) Glycogen synthase
a) Glutaminase
Under fasted conditions, (glucagon is elevated), which of the following enzymes will be phosphorylated and inactive? a) HMG-CoA reductase b) Hormone sensitive lipase c) AMP-activated protein kinase d) Glycogen phosphorylase
a) HMG-CoA reductase
A 52-year- old male sought medical help complaining about progressive appearance of hyperchromic (hyper pigmented) papules on the edge of the second finger of both hands. He also complained about darkening of urine. Incisional biopsy of one of the spots on his hands and urine sample tested positive for or homogentisic acid. Based on these findings a diagnosis of alkaptonuria is made. This diagnosis is consistent with a deficiency in which of the following enzymes? a) Homogentisate oxidase b) Phenylalanine hydroxylase c) Tyrosinase d) α- ketoacid dehydrogenase
a) Homogentisate oxidase
A 45-year-old man is found to have an elevated serum cholesterol of 300mg/dL after a 12 hr. fast. Which of the following lipoproteins would be the largest contributors to a measurement of plasma cholesterol in a normal person following a 12 hr. fast? a) Chylomicron remnants and very-low-density-lipoproteins (VLDLs) b) Chylomicrons and VLDLs c) High-density lipoproteins (HDLs) and LDLs d) LDLs and adipocyte lipid droplets e) VLDLs and LDLs
c) High-density lipoproteins (HDLs) and LDLs
Which of the following is not required for the transport of newly synthesized fatty acids to the adipose? a) Interaction of ApoCII with lipoprotein lipase b) Transport of triacylglycerols from the liver using VLDLs c) Synthesis of triacylglycerol using glycerol 3-phosphate d) Carnitine to shuttle the fatty acids out of the mitochondria
d) Carnitine to shuttle the fatty acids out of the mitochondria
An 11-year-old girl is brought to the emergency department by her father. He reports she has recently been very thirsty and needing to make frequent trips to the bathroom. At her soccer game today, she complained of lightheadedness and that the symptoms did not resolve even after drinking a power beverage. A rapid dipstick test revealed glucose in her urine and further diagnostics are consistent with a diagnosis of type 1 diabetes. Evaluation of this girl's liver would reveal an increased rate of which of the following processes? a) Fatty acid synthesis b) Glycogenesis c) Glycolysis d) Ketogenesis e) Protein synthesis
d) Ketogenesis
The reaction of ammonia with α-ketoglutarate is catalyzed by _________ and requires _________ as a reactant. glutamate dehydrogenase; ATP glutamate synthetase; NADH or NADPH glutamate dehydrogenase; NADH or NADPH glutamate synthetase; ATP
glutamate dehydrogenase; NADH or NADPH
Cholesterol lowering drugs include statins (HMG-CoA inhibitors) and bile acid sequestrants such as cholestyramine. What is the rationale for using this combined therapy for management of hyperlipidemia?
the only real means of excreting excess cholesterol is through bile acids. bile acid synthesis is inhibited by a bile acid. So these bile acid sequestrants sequester bile acids in the intestine and increase the amount secreted in the feces. And by doing that, that reduces the amount that's recycled back to the liver, and thereby, increases bile acid synthesis. We also know that by inhibiting HMG CoA reductase through statins, this will reduce de novo synthesis of intracellular cholesterol. And as the pool of intracellular cholesterol decreases, we can get an increase in uptake of the LDL particles. And both of these are key roles of reducing plasma cholesterol. So if we look at that here, the bile acid sequestrants first will increase our amount of bile acids we can excrete in feces. This reduces the amount of bile acid returned to the liver. And, therefore, we can increase our de novo synthesis of bile acids. This will decrease our intracellular pool of cholesterol and increase LDL uptake. We can also decrease intracellular cholesterol by inhibiting the HMG CoA reductase. And as this pool decreases further, we will, again, increase uptake by LDL. So the enhanced uptake of LDL is our real major contributor to reducing plasma cholesterol in this case.
Select the choice that correctly indicates the proper sequence of the three stages of urea biosynthesis leading to the urea cycle. oxidative deamination of glutamate → ammonia transport → transamination transamination → ammonia transport → oxidative deamination of glutamate transamination → oxidative deamination of glutamate → ammonia transport ammonia transport → oxidative deamination of glutamate → transamination
transamination → oxidative deamination of glutamate → ammonia transport
Hypopigmentation disorder is primarily due to deficient metabolism of which of the following amino acids? Methionine Homocysteine Arginine Tyrosine Cysteine
tyrosine
An increase in the ratio of insulin to glucagon will increase the activity of which of the following enzymes (+ indicates activity is increased; - indicates activity is not increased by insulin)?
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