Podcast
Questions and Answers
In inherited sucrase deficiency, what is the primary consequence of the absence of the sucrase enzyme?
In inherited sucrase deficiency, what is the primary consequence of the absence of the sucrase enzyme?
- Increased absorption of fructose in the small intestine.
- Enhanced production of glucose from galactose.
- Inability to digest sucrose, leading to distension and colic. (correct)
- Stimulation of glycogen synthesis in the liver.
Which of the following monosaccharides is primarily absorbed via simple diffusion?
Which of the following monosaccharides is primarily absorbed via simple diffusion?
- Galactose
- Fructose (correct)
- Glucose
- Sucrose
How does Ouabain affect glucose absorption in the intestines?
How does Ouabain affect glucose absorption in the intestines?
- It directly inhibits the SGLT-1 transporter.
- It promotes facilitated diffusion of glucose.
- It inhibits the $Na^+-K^+$ pump, reducing the sodium gradient needed for glucose cotransport. (correct)
- It enhances the activity of GLUT-5 transporters.
If blood glucose levels exceed the renal threshold (180 mg/dL), what is the likely consequence?
If blood glucose levels exceed the renal threshold (180 mg/dL), what is the likely consequence?
What is the primary purpose of the hexose monophosphate pathway and uronic acid pathway in glucose oxidation?
What is the primary purpose of the hexose monophosphate pathway and uronic acid pathway in glucose oxidation?
During glycolysis, which enzyme facilitates the conversion of glucose to glucose-6-phosphate?
During glycolysis, which enzyme facilitates the conversion of glucose to glucose-6-phosphate?
What is the role of phosphofructokinase-1 (PFK-1) in glycolysis?
What is the role of phosphofructokinase-1 (PFK-1) in glycolysis?
Which enzyme converts dihydroxyacetone phosphate to glyceraldehyde-3-phosphate during glycolysis?
Which enzyme converts dihydroxyacetone phosphate to glyceraldehyde-3-phosphate during glycolysis?
During intense muscle contraction, elevated calcium levels stimulate which enzymes in the citric acid cycle to enhance energy supply?
During intense muscle contraction, elevated calcium levels stimulate which enzymes in the citric acid cycle to enhance energy supply?
Under anaerobic conditions, the citric acid cycle is inhibited due to which of the following reasons?
Under anaerobic conditions, the citric acid cycle is inhibited due to which of the following reasons?
Which of the following conditions would inhibit the activity of citrate synthase, isocitrate dehydrogenase, and $\alpha$-ketoglutarate dehydrogenase?
Which of the following conditions would inhibit the activity of citrate synthase, isocitrate dehydrogenase, and $\alpha$-ketoglutarate dehydrogenase?
Which eicosanoid primarily contributes to reducing cAMP levels in platelets, promoting thrombus formation, and causing vasoconstriction?
Which eicosanoid primarily contributes to reducing cAMP levels in platelets, promoting thrombus formation, and causing vasoconstriction?
Which of the listed disaccharides is commonly found in table sugar?
Which of the listed disaccharides is commonly found in table sugar?
How do steroidal anti-inflammatory drugs alleviate bronchial asthma and anaphylactic shock?
How do steroidal anti-inflammatory drugs alleviate bronchial asthma and anaphylactic shock?
Why are blood samples for glucose estimation often collected in test tubes containing glycolysis inhibitors?
Why are blood samples for glucose estimation often collected in test tubes containing glycolysis inhibitors?
In the digestive system, which enzyme initiates the breakdown of starch in the mouth?
In the digestive system, which enzyme initiates the breakdown of starch in the mouth?
Certain prostaglandins increase cAMP levels in endocrine glands. What is the subsequent effect of this action?
Certain prostaglandins increase cAMP levels in endocrine glands. What is the subsequent effect of this action?
Phosphofructokinase-2 (PFK-2) is described as a bifunctional enzyme. Which of the following best describes its dual activity?
Phosphofructokinase-2 (PFK-2) is described as a bifunctional enzyme. Which of the following best describes its dual activity?
A patient experiencing severe allergic reaction (anaphylactic shock) would likely exhibit symptoms associated with which type of eicosanoid?
A patient experiencing severe allergic reaction (anaphylactic shock) would likely exhibit symptoms associated with which type of eicosanoid?
What is the primary reason for distension and colic in infants with inherited lactase deficiency?
What is the primary reason for distension and colic in infants with inherited lactase deficiency?
If a patient's cells are unable to convert pyruvate into oxaloacetate, which of the following substances would be essential to supplement?
If a patient's cells are unable to convert pyruvate into oxaloacetate, which of the following substances would be essential to supplement?
How does increased succinyl-CoA affect the citric acid cycle?
How does increased succinyl-CoA affect the citric acid cycle?
Which of the following best describes the mechanism by which aspirin prevents thrombus formation?
Which of the following best describes the mechanism by which aspirin prevents thrombus formation?
Through which process does $\alpha$-ketoglutarate transform into glutamate?
Through which process does $\alpha$-ketoglutarate transform into glutamate?
In a cell with high levels of Acetyl-CoA, what effect is expected on the activity of pyruvate carboxylase and why?
In a cell with high levels of Acetyl-CoA, what effect is expected on the activity of pyruvate carboxylase and why?
If a drug inhibits the synthesis of prostaglandins and thromboxanes, which enzyme is most likely being targeted?
If a drug inhibits the synthesis of prostaglandins and thromboxanes, which enzyme is most likely being targeted?
Which of the following phospholipids is also known as lipositol?
Which of the following phospholipids is also known as lipositol?
Which of the following conditions would inhibit the pyruvate dehydrogenase (PDH) complex?
Which of the following conditions would inhibit the pyruvate dehydrogenase (PDH) complex?
During intense exercise, muscle cells produce lactate. How is this lactate primarily utilized when the body returns to a resting state?
During intense exercise, muscle cells produce lactate. How is this lactate primarily utilized when the body returns to a resting state?
What is the direct precursor molecule in the synthesis of phosphatidyl ethanolamine and phosphatidyl choline?
What is the direct precursor molecule in the synthesis of phosphatidyl ethanolamine and phosphatidyl choline?
How many ATP molecules are generated from the oxidative decarboxylation of two pyruvate molecules into two Acetyl-CoA molecules?
How many ATP molecules are generated from the oxidative decarboxylation of two pyruvate molecules into two Acetyl-CoA molecules?
Which of the following tissues is LEAST likely to have active pentose phosphate pathway (HMP)?
Which of the following tissues is LEAST likely to have active pentose phosphate pathway (HMP)?
In sphingolipid catabolism, a deficiency in lysosomal hydrolase enzymes would directly result in:
In sphingolipid catabolism, a deficiency in lysosomal hydrolase enzymes would directly result in:
Which of the following conditions results from a deficiency in the enzyme sphingomyelinase?
Which of the following conditions results from a deficiency in the enzyme sphingomyelinase?
What is the primary endogenous source of cholesterol synthesis?
What is the primary endogenous source of cholesterol synthesis?
How does carbohydrate feeding impact HMG-CoA reductase activity?
How does carbohydrate feeding impact HMG-CoA reductase activity?
Which of the following is NOT a direct role of cholesterol in the body?
Which of the following is NOT a direct role of cholesterol in the body?
What stimulates the key enzyme (7 α - hydroxylase) in bile acid synthesis?
What stimulates the key enzyme (7 α - hydroxylase) in bile acid synthesis?
If a patient has a deficiency in the enzyme $\beta$-Glucosidase, which complex lipid would accumulate in their tissues?
If a patient has a deficiency in the enzyme $\beta$-Glucosidase, which complex lipid would accumulate in their tissues?
Which regulatory mechanism directly involves covalent modification of HMG-CoA reductase?
Which regulatory mechanism directly involves covalent modification of HMG-CoA reductase?
Which of the following best describes the primary consequence of defective chylomicron, VLDL, and LDL formation?
Which of the following best describes the primary consequence of defective chylomicron, VLDL, and LDL formation?
Hypoalphalipoproteinemia, resulting from a failure in apo-A synthesis, primarily affects the formation of which lipoprotein?
Hypoalphalipoproteinemia, resulting from a failure in apo-A synthesis, primarily affects the formation of which lipoprotein?
A deficiency in LCAT (lecithin-cholesterol acyltransferase) would directly lead to what outcome?
A deficiency in LCAT (lecithin-cholesterol acyltransferase) would directly lead to what outcome?
Excessive accumulation of triacylglycerols (TAG) in the liver, leading to fatty liver, can cause what sequence of pathological events?
Excessive accumulation of triacylglycerols (TAG) in the liver, leading to fatty liver, can cause what sequence of pathological events?
Which scenario would most likely lead to over-mobilization of fat from adipose tissue to the liver:
Which scenario would most likely lead to over-mobilization of fat from adipose tissue to the liver:
A deficiency in pantothenic acid can lead to fatty liver by directly impairing:
A deficiency in pantothenic acid can lead to fatty liver by directly impairing:
Lipotropic factors facilitate the mobilization of fat from the liver. What is the most direct mechanism by which these factors accomplish this?
Lipotropic factors facilitate the mobilization of fat from the liver. What is the most direct mechanism by which these factors accomplish this?
Excessive intake of nicotinic acid can lead to depletion of methyl donors, potentially affecting phospholipid synthesis. How does this occur?
Excessive intake of nicotinic acid can lead to depletion of methyl donors, potentially affecting phospholipid synthesis. How does this occur?
Flashcards
Glutamate Source
Glutamate Source
Formed from α-ketoglutarate via transamination.
Aspartate Source
Aspartate Source
This is formed from oxaloacetate.
Acetyl-CoA and Oxaloacetate
Acetyl-CoA and Oxaloacetate
It activates citrate synthase in the citric acid cycle.
Succinyl-CoA
Succinyl-CoA
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High Energy Signals
High Energy Signals
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Calcium's Role in Krebs
Calcium's Role in Krebs
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Common Monosaccharides
Common Monosaccharides
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Common Disaccharides
Common Disaccharides
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Inherited Sucrase Deficiency
Inherited Sucrase Deficiency
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Simple Diffusion (Monosaccharides)
Simple Diffusion (Monosaccharides)
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Facilitated Transport
Facilitated Transport
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Active Transport (Monosaccharides)
Active Transport (Monosaccharides)
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Inhibitors of Glucose Absorption
Inhibitors of Glucose Absorption
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Fates of Absorbed Glucose
Fates of Absorbed Glucose
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Glycolysis
Glycolysis
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Glycolysis Step 1
Glycolysis Step 1
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Prostaglandins
Prostaglandins
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Prostacyclins (PGI2)
Prostacyclins (PGI2)
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Thromboxanes
Thromboxanes
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Leukotrienes
Leukotrienes
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NSAIDs (e.g., Aspirin)
NSAIDs (e.g., Aspirin)
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Steroidal Anti-inflammatory Drugs (e.g., Cortisone)
Steroidal Anti-inflammatory Drugs (e.g., Cortisone)
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Phosphoglycerides
Phosphoglycerides
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Sphingolipids
Sphingolipids
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Glycolysis Inhibitor
Glycolysis Inhibitor
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Phosphofructokinase-2
Phosphofructokinase-2
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Sources of Pyruvate
Sources of Pyruvate
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Fate of Pyruvate
Fate of Pyruvate
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Pyruvate Carboxylase
Pyruvate Carboxylase
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Pyruvate Dehydrogenase (PDH) Complex
Pyruvate Dehydrogenase (PDH) Complex
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Regulation of Pyruvate Dehydrogenase
Regulation of Pyruvate Dehydrogenase
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Hexose Monophosphate Pathway (HMP)
Hexose Monophosphate Pathway (HMP)
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Sphingolipid Catabolism
Sphingolipid Catabolism
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Hypobetalipoproteinemia
Hypobetalipoproteinemia
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Sphingolipidosis
Sphingolipidosis
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Hypoalphalipoproteinemia
Hypoalphalipoproteinemia
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Gaucher's Disease
Gaucher's Disease
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LCAT Deficiency
LCAT Deficiency
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Fatty Liver
Fatty Liver
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Niemann-Pick Disease
Niemann-Pick Disease
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Cholesterol Synthesis Site
Cholesterol Synthesis Site
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Carb Overfeeding (Fatty Liver)
Carb Overfeeding (Fatty Liver)
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Regulation of Cholesterol Synthesis
Regulation of Cholesterol Synthesis
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Pantothenic Acid Deficiency
Pantothenic Acid Deficiency
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Lipotropic Factors
Lipotropic Factors
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Importance of Cholesterol
Importance of Cholesterol
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Liver Toxins
Liver Toxins
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Bile Acid Synthesis
Bile Acid Synthesis
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Study Notes
Bioenergetics and Metabolism
- Metabolism is a reaction series of biochemical processes involving biomolecules in living organisms, including anabolic and catabolic reactions.
Anabolism
- Anabolism is the synthesis of macromolecules from simpler molecules, a process that is usually endergonic, requiring energy input.
- Examples include the synthesis of polysaccharides from monosaccharides, triacylglycerol from glycerol and fatty acids, and proteins from amino acids.
Catabolism
- Catabolism is the breakdown of macromolecules into simpler components which is exergonic releasing energy.
- Catabolism occurs in three stages:
- Stage I involves the digestion of proteins, lipids, and carbohydrates.
- Stage II involves the formation of amino acids, glycerol, fatty acids, and monosaccharides.
- Stage III involves the formation of Acetyl CoA.
Bioenergetics
- Energy is stored in two types of bonds: low energy and high energy, with the key difference is the amount of energy released upon hydrolysis, in Kcal/mole.
- Low energy bonds release less than 7.3 Kcal/mole upon hydrolysis, and they link food stuffs, such as Glycosidic bonds in carbohydrates, Carboxyl-ester bonds in triacylglycerol, and Peptide bonds in protein.
- High energy bonds release more than 7.3 Kcal/mole upon hydrolysis.
ATP
- Released energy is collected in the form of ATP in two forms:
- Substrate level oxidative phosphorylation reactions
- Electron transport chain (respiratory chain) level.
Substrate Level Phosphorylation
- Reactions produce energy directly in the form of ATP.
- ATP is produced at the substrate level in two reactions in glycolysis and one in the citric acid cycle.
- Krebs' cycle: One reaction is Succinyl Co A with thiokinase, resulting in succinate + ATP
- Glycolysis: 2 reactions involve Biphospoglycerate (phosphoglycerate kinase to phosphoglycerate +ATP) and Phosphoenol pyruvate (pyruvate kinase to pyruvate + AТР)
Electron Transport Chain
- Electron transport chains or respiratory chains consist of a series of hydrogen transfers from complexes that are more electronegative to oxygen an electropositive form of water,which releases energy in the form of ATP.
Electron Transport Chain Components
- Components are present in 4 complexes, CoQ, and cytochrome c
- Complex I consists of FMN, NADH dehydrogenase (7FeS groups) and many polypeptides and transfers it to CoQ forming (CoQH2) with production of one ATP.
- Complex II consists of FAD Succinate dehydrogenase, and 2 FeS groups where FADH2 transfers hydrogen from succinate to CoQ to form CoQH2 without production of ATÐ .
- CoQ is the main station between complex I and complex II.
- Complex III consists of Cytochromes b & C and one iron sulfur FeS group that transfers electrons from CoQH: to cytochrome releasing four protons with production of one ATP.
- Complex IV consists of Cytochromes a-a3 (a hemoprotein contains iron) and 2 Copper atoms that transfers electrons from cytochrome c to oxygen which combines with the two protons to form water with of production 0.5ATP.
- Flavoproteins exist in Complex I as FMN and Complex II as FAD.
- Protons are pumped through complexes I, III & IV.
Chemiosmotic Theory of ATP Synthesis
- Chemiosmotic theory of ATP synthesis involves ATP synthase enzyme (complex V), consisting of two subunits, F0 and F1.
- The F0 subunit through which protons return to the mitochondrial matrix according to their concentration gradients.
- Coupled with the F1 subunit couples ADP with Pi to form ATP.
ATP Transporter
- ATP Transporter (Translocater) exchanges ADP to (ATP formed in respiratory chain) to avoid inhibition of ETC by the accumulated ATP.
Regulation of respiratory chain
- Respiratory chain is inhibited in the absence of oxygen (under anaerobic conditions).
- ADP and AMP are the major control substances of E.T.C. -E.T.C. is inhibited by excess ATP (energy in the cell) and is stimulated by ADP and highly stimulated by AMP.
P/O Ratio
- P/O ratio is the ratio between inorganic phosphate consumed to form ATP in relation to the oxygen atom reduced to form water in the respiratory chain.
- Oxidation of NADH,H = 2.5 ATPs, formed at 3 coupling sites.
- Oxidation of FADH2 = 1.5 ATPs, formed at 2 coupling sites.
Storage of energy
- Energy is stored in the form of creatine phosphate in muscles, collected in the form of ATP and starts this reaction: Creatine + ATP via Creatine phosphokinase (CPK), creates Creatine ~P ++ ADP.
Uncouplers
- Uncouplers dissociate oxidation from phosphorylation and include physiological uncouplers:
- Calcium ions, Thyroxin hormone and Thermogenin (physiological uncoupler present in adipose tissue), responsible for energy released as heat and in human babies who cannot shiver to generate heat
- Pharmacological uncouplers : 2,3 Dinitrophenol affect ion and proton transport through the mitochondrial membrane and disrupt electrochemical gradients, allowing protons to pass through gate F2 and release energy as heat.
The Citric Acid Cycle
- The citric acid cycle (also known as the Krebs Cycle) is a series of chemical reactions for the complete oxidation of active acetate (acetyl ~ SCoA) derived from carbohydrates, fats, and proteins.
- All components of the cycle are located freely in the mitochondrial matrix except succinate dehydrogenase, which is present in the inner mitochondrial membrane.
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