Glucose Transport Systems Quiz
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Glucose Transport Systems Quiz

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Questions and Answers

Which glucose transporter is responsible for basal glucose uptake in almost all mammalian cells?

  • GLUT2
  • GLUT1 (correct)
  • GLUT4
  • GLUT3

    • In what type of cells is GLUT-3 the primary glucose transporter?

  • Neurons (correct)
  • Muscle cells
  • Fat cells
  • Liver cells

    • Which glucose transporter is present in the liver and pancreatic β cells and allows glucose to rapidly enter liver cells only in times of plenty glucose levels?

  • GLUT3
  • GLUT2 (correct)
  • GLUT1
  • GLUT4

    • Which glucose transporter is insulin-dependent and transports glucose into muscle and fat cells?

    <p>GLUT4</p> Signup and view all the answers

    Which glucose transporter functions primarily as a fructose transporter and is present in the small intestine?

    <p>GLUT5</p> Signup and view all the answers

    Which glucose transporter in the GLUT family has a Km of around 15-20 mM and plays a role in sensing glucose levels in the pancreas?

    <p>GLUT2</p> Signup and view all the answers

    Which term best describes the breakdown of 1 molecule of glucose to 2 molecules of pyruvate in the glycolysis pathway?

    <p>Glycolysis</p> Signup and view all the answers

    In which cellular compartment does glycolysis take place?

    <p>Cytosol</p> Signup and view all the answers

    Which tissues rely primarily on glycolytic breakdown of glucose as their main source of metabolic energy?

    <p>Brain tissue</p> Signup and view all the answers

    What is the main purpose of the Pentose Phosphate Pathway in glucose metabolism?

    <p>Generate NADPH for reductive biosynthetic processes</p> Signup and view all the answers

    Under aerobic conditions, what is the fate of pyruvate produced from glycolysis?

    <p>Converted to CO2 for more ATP production</p> Signup and view all the answers

    What are the characteristics of the preparatory phase of glycolysis?

    <p>Requires priming steps that demand energy</p> Signup and view all the answers

    What are the three enzymes in glycolysis that are potential regulation sites due to catalyzing virtually irreversible reactions?

    <p>Hexokinase, pyruvate kinase, and phosphofructokinase</p> Signup and view all the answers

    In glycolysis, what initiates an increase in the amount of glucokinase, phosphofructokinase, and pyruvate kinase in the liver?

    <p>Meals rich in carbohydrates</p> Signup and view all the answers

    What effect does glucagon have on the activity of enzymes like glucokinase, phosphofructokinase, and pyruvate kinase?

    <p>Diminishes their activity</p> Signup and view all the answers

    Which enzyme is inhibited by high levels of glucose 6-phosphate (G6P), indicating that the cell doesn't require glucose for energy or glycogen synthesis?

    <p>Hexokinase</p> Signup and view all the answers

    What initiates an increase in the synthesis of glucokinase by the liver?

    <p>Elevation of blood glucose levels after a meal</p> Signup and view all the answers

    What is the primary function of glycolysis in muscle?

    <p>To provide ATP for muscle contraction</p> Signup and view all the answers

    What is the main control site in the mammalian glycolytic pathway?

    <p>Phosphofructokinase (PFK)</p> Signup and view all the answers

    In muscle functioning anaerobically, why is the inhibitory effect of phosphofructokinase important?

    <p>To protect the muscle from damage</p> Signup and view all the answers

    How is pyruvate kinase affected by high levels of ATP?

    <p>Inhibited</p> Signup and view all the answers

    What is the role of glucokinase in the liver?

    <p>Converts glucose to glycogen</p> Signup and view all the answers

    How is glucokinase activity regulated in the liver?

    <p>Indirectly inhibited by fructose 6-phosphate</p> Signup and view all the answers

    What activates phosphofructokinase (PFK) in the liver?

    <p>[F-2,6-BP] increase</p> Signup and view all the answers

    What is the rationale behind the cleavage of F-1,6-Bisphosphate in glycolysis?

    <p>To convert a six-carbon sugar into two three-carbon sugars.</p> Signup and view all the answers

    Why is Phosphofructokinase-1 in glycolysis considered highly regulated?

    <p>It catalyzes an irreversible reaction.</p> Signup and view all the answers

    What is the purpose of the oxidation of Glyceraldehyde 3-Phosphate to 1,3Bisphosphoglycerate in glycolysis?

    <p>To create a high-energy phosphate compound.</p> Signup and view all the answers

    Why is the migration of the phosphate important in glycolysis?

    <p>To form high-energy phosphate compounds.</p> Signup and view all the answers

    Which process in glycolysis involves dehydration of 2-PG to PEP?

    <p>Conversion of Fructose 6-Phosphate to Fructose 1,6 bis-Phosphate.</p> Signup and view all the answers

    What is the primary reason for keeping the concentration of Glyceraldehyde-3-Phosphate low during glycolysis?

    <p>To pull reactions forward.</p> Signup and view all the answers

    Which pathway regenerates NAD+ for further glycolysis under anaerobic conditions?

    <p>Lactic acid fermentation</p> Signup and view all the answers

    In what type of cells does the reduction of pyruvate to ethanol occur?

    <p>Muscle cells</p> Signup and view all the answers

    Which pathway involves the reduction of pyruvate to lactate?

    <p>Lactic Acid Fermentation</p> Signup and view all the answers

    What is the fate of pyruvate under aerobic conditions?

    <p>Oxidized to acetate for the citric acid cycle</p> Signup and view all the answers

    Which tissues rely primarily on anaerobic glycolysis for energy production?

    <p>Muscle</p> Signup and view all the answers

    Under hypoxic conditions, how is NAD regenerated?

    <p>Lactic acid fermentation</p> Signup and view all the answers

    What happens to lactate released from cells undergoing anaerobic glycolysis in the liver?

    <p>It is used to synthesize glucose which is then returned to the blood</p> Signup and view all the answers

    What is the primary function of the Cori Cycle?

    <p>Metabolic cooperation between skeletal muscle and the liver</p> Signup and view all the answers

    In glycolysis, why is there a need for shuttles like the Glycerol 3-phosphate shuttle?

    <p>To transport NADH across the mitochondrial inner membrane</p> Signup and view all the answers

    What is the major function of the Malate–aspartate shuttle in glycolysis?

    <p>Transport NADH across the mitochondrial inner membrane</p> Signup and view all the answers

    Which statement accurately describes the fate of lactate in many tissues?

    <p>It is oxidized to pyruvate and then to CO2 in the TCA cycle</p> Signup and view all the answers

    What role does oxygen supply play in determining the fate of lactate in tissues?

    <p>It enhances the conversion of lactate to pyruvate</p> Signup and view all the answers

    Where do glycolytic NADH molecules undergo reoxidation to keep the glycolytic pathway functional?

    <p>Inner mitochondrial membrane</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of malate to oxaloacetate in the malate-aspartate shuttle?

    <p>Malate dehydrogenase</p> Signup and view all the answers

    What is the main reason for using the malate-aspartate shuttle for NADH reoxidation in liver, heart, and kidney cells?

    <p>Prevention of NADH accumulation in the cytoplasm</p> Signup and view all the answers

    Which molecule is not involved in the feeder pathways for glycolysis?

    <p>Pyruvate</p> Signup and view all the answers

    What is the primary function of the glycerol phosphate shuttle in oxidative phosphorylation?

    <p>Formation of mitochondrial FADH2</p> Signup and view all the answers

    What is the role of glycogen phosphorylase in the feeder pathways for glycolysis?

    <p>Converting glycogen to glucose-1-phosphate</p> Signup and view all the answers

    What is the role of Succinate Dehydrogenase in the TCA cycle?

    <p>Catalyzes the conversion of succinate to fumarate</p> Signup and view all the answers

    Where does the citric acid cycle (TCA cycle) primarily occur in eukaryotic cells?

    <p>Mitochondrial matrix</p> Signup and view all the answers

    Which stage of cellular respiration involves the generation of GTP?

    <p>Stage 2: Acetyl-CoA Oxidation</p> Signup and view all the answers

    What is the function of the Pyruvate Dehydrogenase Complex in cellular respiration?

    <p>Converts pyruvate to acetyl-CoA</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of pyruvate to acetyl-CoA in the mitochondria?

    <p>Pyruvate Dehydrogenase Complex</p> Signup and view all the answers

    What is the main function of the Citric Acid Cycle (TCA cycle) in cellular metabolism?

    <p>Produce reducing equivalents NADH and FADH2</p> Signup and view all the answers

    What is the role of arsenite in inhibiting the pyruvate dehydrogenase complex?

    <p>It affects lipoic acid in the complex</p> Signup and view all the answers

    Which of the following is NOT an advantage of multienzyme complexes like the pyruvate dehydrogenase complex (PDC)?

    <p>Increases the complexity of regulation</p> Signup and view all the answers

    What is the prosthetic group involved in the inhibition of aconitase by fluorocitrate?

    <p>FAD</p> Signup and view all the answers

    How is Succinate Dehydrogenase different from Isocitrate Dehydrogenase and α-Ketoglutarate Dehydrogenase?

    <p>Have different active sites for substrates</p> Signup and view all the answers

    Which enzyme catalyzes the conversion of Succinyl-CoA to Succinate in the TCA cycle?

    <p>Succinate Thio kinase</p> Signup and view all the answers

    Why is the hydration of Fumarate to Malate considered a stereospecific trans addition by Fumarase?

    <p>Only one side of fumarate receives an OH- group</p> Signup and view all the answers

    What happens in tissues capable of fatty acid synthesis when there is an inhibition of isocitrate dehydrogenase?

    <p>Buildup of citrate leading to the cessation of glycolysis.</p> Signup and view all the answers

    What is the consequence of inhibiting α-ketoglutarate dehydrogenase?

    <p>Buildup of α-ketoglutarate used for the synthesis of many amino acids and purine bases.</p> Signup and view all the answers

    What does a rise in mitochondrial Ca2+ levels lead to in terms of pyruvate dehydrogenase activity?

    <p>Enhances the phosphatase activity for acetyl CoA production.</p> Signup and view all the answers

    In tissues capable of fatty acid synthesis, what role does insulin play in relation to pyruvate?

    <p>Stimulates the phosphatase for the conversion of pyruvate into acetyl CoA.</p> Signup and view all the answers

    What is the significance of a buildup of citrate due to isocitrate dehydrogenase inhibition?

    <p>Signals glycolysis to stop.</p> Signup and view all the answers

    Which enzyme catalyzes the step in the citric acid cycle that involves substrate-level phosphorylation to give GTP?

    <p>Succinyl-CoA synthetase</p> Signup and view all the answers

    Which vitamin is required for the citric acid cycle as a precursor to Coenzyme A (CoA)?

    <p>Pantothenic Acid (B5)</p> Signup and view all the answers

    What is the net result of the citric acid cycle on a per Acetyl-CoA basis?

    <p>2 NADH, 1 FADH2, 1 GTP</p> Signup and view all the answers

    Which enzyme is primarily responsible for the regulation of Pyruvate Dehydrogenase Complex through reversible phosphorylation?

    <p>Pyruvate dehydrogenase kinase</p> Signup and view all the answers

    Which statement accurately describes the regulation of the Citric Acid Cycle?

    <p>Activated by substrate availability, inhibited by product accumulation</p> Signup and view all the answers

    Which vitamin functions as a precursor to FAD, an essential cofactor in the citric acid cycle for electron transfer reactions?

    <p>Riboflavin (B2)</p> Signup and view all the answers

    What is the main purpose of PEP carboxykinase in gluconeogenesis?

    <p>Converts pyruvate to phosphoenolpyruvate</p> Signup and view all the answers

    Which enzyme is the first regulatory enzyme in the gluconeogenic pathway?

    <p>Pyruvate carboxylase</p> Signup and view all the answers

    What source of energy does GTP provide in the conversion of oxaloacetate to phosphoenolpyruvate?

    <p>Phosphate group</p> Signup and view all the answers

    Where does phosphoenolpyruvate carboxykinase (PEPCK) primarily convert oxaloacetate to phosphoenolpyruvate?

    <p>Cytosol</p> Signup and view all the answers

    What factor determines the relative importance of the two pathways from pyruvate to phosphoenolpyruvate?

    <p>Presence of lactate or pyruvate</p> Signup and view all the answers

    What effect does glucagon have on fructose 1,6-bisphosphatase activity in response to low glucose levels?

    <p>Activates it</p> Signup and view all the answers

    Which enzyme does glucagon inhibit to decrease the concentration of fructose 2,6-bisphosphate in the liver?

    <p>PFK-2</p> Signup and view all the answers

    Where is glucagon primarily produced in the body?

    <p>Pancreas</p> Signup and view all the answers

    What effect does glucagon have on glucose export into the bloodstream from muscle and adipose tissue?

    <p>Halts it completely</p> Signup and view all the answers

    What is the transcriptional effect of glucagon on PEP-carboxykinase?

    <p>Induction</p> Signup and view all the answers

    What is the exception to the rule that glucose cannot be synthesized from fatty acids?

    <p>Propionate</p> Signup and view all the answers

    Which molecule can be converted to glucose through the generation of dihydroxyacetone phosphate?

    <p>Fructose</p> Signup and view all the answers

    Where does pyruvate carboxylase convert pyruvate into oxaloacetate?

    <p>Mitochondria</p> Signup and view all the answers

    Which enzyme is involved in the first energy-consuming step to convert pyruvate into oxaloacetate?

    <p>Pyruvate carboxylase</p> Signup and view all the answers

    Which location does glucose 6-phosphatase primarily occupy?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What is the importance of UDPglucose in the conversion of galactose into glucose?

    <p>Recycling intermediate</p> Signup and view all the answers

    What enzyme catalyzes the reverse reaction of the opposing step in glycolysis during gluconeogenesis?

    <p>Fructose bisphosphatase-1</p> Signup and view all the answers

    Which enzyme is responsible for converting Fructose 1,6-bisphosphate to Fructose 6-phosphate in gluconeogenesis?

    <p>Fructose bisphosphatase-1</p> Signup and view all the answers

    Where is Glucose 6-phosphatase found in hepatocytes and renal cells?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What is the cost in terms of ATP, GTP, and NADH for producing one molecule of glucose through gluconeogenesis?

    <p>4 ATP, 2 GTP, 2 NADH</p> Signup and view all the answers

    Which cells rely ONLY on glucose for ATP generation?

    <p>Brain, nervous system, and red blood cells</p> Signup and view all the answers

    When do the bypasses of fructose bisphosphatase-1 and glucose 6-phosphatase occur in gluconeogenesis?

    <p>During starvation</p> Signup and view all the answers

    What effect does increased concentration of acetyl-CoA have on pyruvate carboxylase and the pyruvate dehydrogenase complex in the context of gluconeogenesis?

    <p>Inhibits pyruvate carboxylase and activates the pyruvate dehydrogenase complex</p> Signup and view all the answers

    Under which conditions is pyruvate carboxylase active?

    <p>Elevated levels of Acetyl CoA</p> Signup and view all the answers

    What is the role of Fructose 2,6-Bisphosphate in the liver in terms of glycolysis and gluconeogenesis?

    <p>It is a positive allosteric effector of PFK-1 and an inhibitor of fructose-1,6-bisphosphatase</p> Signup and view all the answers

    What induces Phosphoenolpyruvate carboxykinase, an enzyme involved in gluconeogenesis?

    <p>Glucagon</p> Signup and view all the answers

    What is the impact of high ATP and citrate levels on cellular metabolism?

    <p>Indicate high energy charge and abundant biosynthetic intermediates</p> Signup and view all the answers

    How do glucagon and insulin influence the regulation of gluconeogenesis?

    <p>Glucagon promotes gluconeogenesis while insulin inhibits it</p> Signup and view all the answers

    Which enzyme is required for the synthesis of glycogen from UDP-glucose?

    <p>UDP-glucose pyrophosphorylase</p> Signup and view all the answers

    What is the high-energy carrier involved in glycogen synthesis?

    <p>UDP-glucose</p> Signup and view all the answers

    In glycogen synthesis, what is the function of branching enzyme?

    <p>Catalyzes formation of branch points in glycogen molecules</p> Signup and view all the answers

    Which enzyme is necessary for the de novo synthesis of a new glycogen molecule in addition to the regular glycogen synthesis enzymes?

    <p>Glycogenin</p> Signup and view all the answers

    What is the activated form of glucose used in glycogen synthesis?

    <p>UDP-glucose</p> Signup and view all the answers

    Where does de novo synthesis of glycogen predominantly occur?

    <p>Cytosol</p> Signup and view all the answers

    Why is glycogen considered a good source of fuel for anaerobic activity?

    <p>Glycogen can be used as an energy source even in the absence of oxygen.</p> Signup and view all the answers

    Where is glycogen principally stored in the body?

    <p>Cytosol granules of liver and muscle cells</p> Signup and view all the answers

    What is the significance of the large number of nonreducing ends in glycogen structure?

    <p>They allow for rapid mobilization of glycogen stores.</p> Signup and view all the answers

    What is the average distance between branch points in glycogen structure?

    <p>8-10 residues</p> Signup and view all the answers

    How does the regulation of glycogen synthesis and breakdown differ between skeletal muscle and liver cells?

    <p>Skeletal muscle cells break down glycogen for immediate use while liver cells maintain blood glucose levels.</p> Signup and view all the answers

    What role does the large number of nonreducing ends play in glycogen metabolism?

    <p>They are required for the regulation of enzymes involved in glycogen metabolism.</p> Signup and view all the answers

    What is the primary function of glycogen phosphorylase?

    <p>Catalyzes the removal of glucosyl residues from glycogen</p> Signup and view all the answers

    What is the purpose of the debranching enzyme in glycogenolysis?

    <p>To cleave a-1,6 linkages in glycogen</p> Signup and view all the answers

    What is the outcome of the phosphorolysis reaction catalyzed by glycogen phosphorylase?

    <p>Removal of glucosyl residues from glycogen</p> Signup and view all the answers

    What is the role of transferase in glycogen breakdown activities?

    <p>Moves a-1,4 linkages to a-1,6 linkages</p> Signup and view all the answers

    What is the role of glycogenin in glycogen synthesis?

    <p>Catalyzes the addition of the initial glucosyl unit to tyrosine</p> Signup and view all the answers

    Which enzyme catalyzes the conversion of Glucose 6-phosphate into Glucose?

    <p>Glucose 6-phosphatase</p> Signup and view all the answers

    What serves as the primer for glycogen synthesis before glycogen synthase takes over?

    <p>Glycogenin</p> Signup and view all the answers

    What is the significance of branching in glycogen regarding its solubility?

    <p>Branching increases solubility of glycogen</p> Signup and view all the answers

    Which enzyme forms α-1,6 linkages to facilitate branching in glycogen synthesis?

    <p>Branching enzyme</p> Signup and view all the answers

    What is the minimum length of the a-1,4 chain required for branching by glucosyl α-4:6 transferase?

    <p>~9-11 residues</p> Signup and view all the answers

    What activates branching enzyme to facilitate branching in glycogen synthesis?

    <p>High levels of ATP</p> Signup and view all the answers

    Which enzyme breaks the α-1,4 link and forms α-1,6 linkages in the process of remodeling during glycogen synthesis?

    <p>Branching enzyme</p> Signup and view all the answers

    What is the role of transferase in glycogen metabolism?

    <p>Transfers a block of three residues to the non-reducing end of the chain</p> Signup and view all the answers

    What is the function of α-1,6-Glucosidase in glycogen metabolism?

    <p>Cleaves alpha-1,6-linked glucose residues</p> Signup and view all the answers

    What is the fate of glucose 6-phosphate in the liver?

    <p>Converted to glucose by dephosphorylation</p> Signup and view all the answers

    Where are the transferase and α-1,6-Glucosidase activities located in eukaryotes?

    <p>Within one bifunctional protein</p> Signup and view all the answers

    In prokaryotes, how is glucose 1-phosphate converted to glucose 6-phosphate?

    <p>By phosphoglucomutase</p> Signup and view all the answers

    What enables glucose to leave the liver?

    <p>Glucose 6-phosphatase enzyme</p> Signup and view all the answers

    What is the significance of having a large number of nonreducing ends in glycogen structure?

    <p>They are required as substrates for the enzymes of glycogen metabolism.</p> Signup and view all the answers

    Why is glycogen considered a good source of fuel for anaerobic activity?

    <p>It is quickly mobilized in muscle.</p> Signup and view all the answers

    In which organelle is glycogen principally stored in the cytosol granules?

    <p>Mitochondria</p> Signup and view all the answers

    How are the branch points structured in glycogen?

    <p>Every 8-10 residues</p> Signup and view all the answers

    What is the main reason for storing glucose as glycogen?

    <p>To maintain blood glucose levels during fasting</p> Signup and view all the answers

    What is the role of glycogen in liver cells?

    <p>Maintains blood glucose levels</p> Signup and view all the answers

    What enzyme catalyzes the formation of UDP-glucose from Glucose-1-phosphate and UTP during glycogen synthesis?

    <p>UDP-glucose pyrophosphorylase</p> Signup and view all the answers

    Which enzyme is essential for catalyzing the attachment of glucose residues in the autoglucosylation process during glycogen synthesis?

    <p>Glycogenin</p> Signup and view all the answers

    In what form is glucose primarily transported during glycogen synthesis?

    <p>UDP-glucose</p> Signup and view all the answers

    Which enzyme is responsible for catalyzing the addition of glucose to the nonreducing end during glycogen synthesis?

    <p>Glycogen synthase</p> Signup and view all the answers

    What is the role of branching enzyme (glucosyl transferase) in glycogen synthesis?

    <p>Forms α-1,6 linkages to create glycogen branches</p> Signup and view all the answers

    What is the activated form of glucose used in the synthesis of glycogen?

    <p>UDP-glucose</p> Signup and view all the answers

    What is the role of glycogenin in glycogen synthesis?

    <p>Catalyzes the transfer of glucose molecules from UDP-glucose to form a primer</p> Signup and view all the answers

    What is the function of branching enzyme in glycogen synthesis?

    <p>Cleaves α-1,4 linkages and forms α-1,6 linkages to create branches</p> Signup and view all the answers

    How does glycogen synthase contribute to glycogen synthesis?

    <p>Adds glucose residues to the existing glycogen chain</p> Signup and view all the answers

    What is the consequence of inhibiting the activity of glycogenin in glycogen synthesis?

    <p>Inability to elongate the glycogen chain beyond a few glucose molecules</p> Signup and view all the answers

    How does glycogen branching facilitate both degradation and synthesis processes?

    <p>Provides substrate sites at non-reducing ends for enzyme action</p> Signup and view all the answers

    What is the significance of glycogenin remaining permanently attached to the reducing end of the glycogen molecule?

    <p>Allows for continuous addition of new glucose residues to the chain</p> Signup and view all the answers

    What is the main function of the debranching enzyme in glycogenolysis?

    <p>Cleave a-1,6 linkages</p> Signup and view all the answers

    What is the primary role of the phosphorylase enzyme in glycogen metabolism?

    <p>Cleave a-1,4 linkages</p> Signup and view all the answers

    What is the significance of branching in glycogen structure?

    <p>Increases solubility of glycogen</p> Signup and view all the answers

    Which enzyme is responsible for remodeling glycogen to ensure it remains a substrate for degradation?

    <p>Transferase</p> Signup and view all the answers

    What process involves the removal of glucosyl residues from the nonreducing ends of the glycogen molecule?

    <p>Phosphorolysis</p> Signup and view all the answers

    What is the final step in the glycogen breakdown process?

    <p>Cleavage by glucosidase</p> Signup and view all the answers

    What enzyme works on non-reducing ends until it reaches four residues from an (a1→ 6) branch point in glycogen metabolism?

    <p>Glycogen phosphorylase</p> Signup and view all the answers

    In eukaryotes, where are the transferase and α-1,6-Glucosidase activities located?

    <p>Within one bifunctional protein</p> Signup and view all the answers

    Which enzyme is responsible for converting glucose 1-phosphate to glucose 6-phosphate in prokaryotes?

    <p>Phosphoglucomutase</p> Signup and view all the answers

    What enzyme dephosphorylates glucose-6-phosphate in the liver for transport out of the liver?

    <p>Glucose 6-phosphatase</p> Signup and view all the answers

    In which organ can glucose leave due to the presence of glucose 6-phosphatase?

    <p>Liver</p> Signup and view all the answers

    Which enzyme enables glucose to leave the liver by hydrolyzing glucose 6-phosphate?

    <p>Glucose 6-phosphatase</p> Signup and view all the answers

    What is the principal building block of fatty acids?

    <p>Acetyl CoA</p> Signup and view all the answers

    Which molecule acts as a feedback inhibitor of the enzyme involved in fatty acid synthesis?

    <p>Acetyl CoA</p> Signup and view all the answers

    What is the source of NADPH in fatty acid synthesis?

    <p>Malate</p> Signup and view all the answers

    Which process is considered the rate-limiting step in the biosynthesis of fatty acids?

    <p>Acetyl-CoA carboxylase reaction</p> Signup and view all the answers

    Which molecule plays a central role in diverting cellular metabolism towards storage as fatty acids instead of consumption?

    <p>Citrate</p> Signup and view all the answers

    What cellular compartment does fatty acid synthesis primarily occur in?

    <p>Cytosol</p> Signup and view all the answers

    What is the primary function of phosphatidic acid phosphatase in the pathway to TAGs?

    <p>Hydrolyzing phosphatidic acid to form 1,2-diacylglycerol</p> Signup and view all the answers

    In which tissue does glyceroneogenesis coupled with reesterification of FFA control the rate of FA release to the blood?

    <p>Adipose tissue</p> Signup and view all the answers

    What is the role of glyceroneogenesis in brown adipose tissue in relation to mitochondria?

    <p>Control delivery of FFA to mitochondria for thermogenesis</p> Signup and view all the answers

    During fasting in humans, what percentage of fatty acids reesterified to triacylglycerol is supported by glyceroneogenesis in the liver?

    <p>65%</p> Signup and view all the answers

    What is the final product formed by transesterification with a third fatty acyl–CoA in the conversion of diacylglycerols to TAGs?

    <p>TAGs</p> Signup and view all the answers

    What is the principal form of stored energy in most organisms?

    <p>Triacylglycerols</p> Signup and view all the answers

    What is the reducing agent in the fatty acid synthetic sequence?

    <p>NADPH</p> Signup and view all the answers

    Which enzyme catalyzes the formation of malonyl-CoA from acetyl-CoA?

    <p>Acetyl-CoA carboxylase</p> Signup and view all the answers

    What specialized lipids serve as pigments and cofactors?

    <p>Retinal and carotene</p> Signup and view all the answers

    In fatty acid synthesis, what activates the groups on the enzyme-bound -SH groups?

    <p>ATP</p> Signup and view all the answers

    What happens when the fatty acyl chain reaches a length of 16 in the synthesis cycle?

    <p>It leaves the cycle as palmitate</p> Signup and view all the answers

    Which fatty acids are essential for mammals and must be obtained from dietary plant material?

    <p>Linoleate</p> Signup and view all the answers

    What is the precursor of regulatory lipids, the eicosanoids?

    <p>Arachidonate</p> Signup and view all the answers

    Which enzyme is responsible for the formation of fatty acyl esters of glycerol?

    <p>Fatty Acyl–CoA Synthetases</p> Signup and view all the answers

    What is the central intermediate in lipid biosynthesis that can be converted to either triacylglycerols or glycerophospholipids?

    <p>Phosphatidic Acid</p> Signup and view all the answers

    What is the precursor of eicosatrienoate and arachidonate, which can only be made from this specific fatty acid?

    <p>Linoleate</p> Signup and view all the answers

    What effect does phosphorylation have on acetyl-CoA carboxylase activity?

    <p>Inhibits the enzyme</p> Signup and view all the answers

    Where does fatty acid elongation primarily take place?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    Which enzyme catalyzes the introduction of double bonds into fatty acid chains?

    <p>Desaturase</p> Signup and view all the answers

    What is the role of NADPH in fatty acid elongation?

    <p>Donates reducing equivalents</p> Signup and view all the answers

    Which fatty acids serve as precursors for the synthesis of palmitoleate and oleate?

    <p>Palmitate and stearate</p> Signup and view all the answers

    What happens to acetyl-CoA carboxylase when it is in its active form?

    <p>Polymerizes into long filaments</p> Signup and view all the answers

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