11. A 48-year-old patient is brought to the emergency room after exposure to toxic fumes suspected to contain cyanide. He presents with shortness of breath, confusion, and metabolic acidosis. The medical team suspects cyanide toxicity, which disrupts the electron transport chain (ETC). Which of the following statements concerning the components of the electron transport chain […]
1. A 60-year-old man is admitted to the hospital with confusion, fatigue, and muscle weakness. His symptoms suggest mitochondrial dysfunction, potentially caused by exposure to a toxin that inhibits the electron transport chain. Laboratory tests reveal a disruption in ATP production, and the medical team suspects inhibition at Complex I. Which of the following is
Hexokinase vs Glucokinase Regulation Feature Hexokinase Glucokinase Mnemonic Location Most tissues (muscle, brain) Liver and pancreatic β-cells “H in Human Tissues, G in Glucose Factories” Affinity for Glucose (Km) Low Km (high affinity) High Km (active only at high glucose) “Hexokinase is Hungry, Glucokinase is Greedy” Allosteric Inhibition Inhibited by Glucose-6-Phosphate No inhibition by Glucose-6-Phosphate
A Summary Of Regulation of Glycolysis, PDH Complex, and TCA Cycle (with mnemonics) Read More »
Site of Action Inhibitors / Uncouplers Mechanism Mnemonic for Easy Recall Complex I (NADH Dehydrogenase) Rotenone, Piericidin A, Amytal Blocks electron transfer from NADH to CoQ “Rotten Pies Available” (Rotenone, Piericidin A, Amytal block Complex I) Complex II (Succinate Dehydrogenase) Malonate, Carboxin, TTFA Competes with succinate, preventing electron transfer to CoQ “Malonate Causes Trouble Fast”
ETC Inhibitors, Uncouplers, and Transporter Inhibitors of Oxidative Phosphorylation Read More »
Type of Inhibition Effect on Vmax and Km Reversible / Irreversible Examples Mnemonic Competitive (Inhibitor competes with substrate for the active site) Vmax: Unchanged Km: Increased Reversible 1) Statins – inhibit HMG-CoA Reductase (cholesterol-lowering) 2) PABA – inhibits Pteroyl Synthase (antibiotic) 3) Captopril – inhibits ACE (antihypertensive) 4) Oxamate – inhibits Lactate Dehydrogenase (poison) 5)
Types of Enzyme Inhibition with Mnemonics Read More »
Here’s a table showing the amino acids associated with each intermediate and helpful mnemonics to aid memorization: Intermediate Amino Acids Associated Mnemonic for Amino Acid Entry Points Pyruvate Glycine, Alanine, Serine, Cysteine, Threonine, Tryptophan, Hydroxyproline G – Glycine A – Alanine S – Serine C – Cysteine T – Threonine T – Tryptophan H – Hydroxyproline
Amino acids associated with the TCA cycle and helpful mnemonics to aid memorization Read More »
1. The cytosolic isoform of which of the following TCA cycle enzymes requires NADP⁺ as a coenzyme, which can be utilized in the reduced state for reductive biosynthesis? A. Aconitase B. Citrate Synthase C. Isocitrate Dehydrogenase D. Malate Dehydrogenase E. Succinate Dehydrogenase The correct answer is C: Isocitrate Dehydrogenase: The cytosolic isoform of isocitrate dehydrogenase
PDH complex and the TCA cycle- NBME style questions set-2 Read More »
1. A 24-year-old woman presents with diarrhea, dysphagia, jaundice, and white transverse lines on her fingernails (Mee’s lines). She is diagnosed with arsenic poisoning. Arsenic poisoning inhibits which of the following enzymes? A. Citrate synthase B. Isocitrate dehydrogenase C. Malate dehydrogenase D. Succinate dehydrogenase E. α-Keto glutarate dehydrogenase complex Correct answer: E. α-Keto glutarate dehydrogenase
PDH complex and the TCA cycle- NBME style questions set-1 Read More »
Q.1 Identify the Phosphoester that is predominantly encountered in erythrocytes and plays a vital role in modulating the oxygen-binding affinity of hemoglobin: A. 1,3-Bisphosphoglycerate B. 2,3-Bisphosphoglycerate C. Fructose 1,6-bisphosphate D. Fructose 6-phosphate E. Glucose 6-phosphate The correct answer is B. 2,3-Bisphosphoglycerate (2,3-BPG): 2,3-Bisphosphoglycerate is a negatively charged molecule found in high concentrations within erythrocytes. 2,3-BPG
Glycolysis Review- NBME style questions with complete explanations Read More »
Question 1: A 25-year-old man runs a marathon. After 20 miles, his muscle cells are relying heavily on glycolysis for energy production. Which of the following changes is most likely increasing the rate of glycolysis in his muscles? A. Accumulation of alanine B. Decreased availability of glucose C. Decreased oxygen levels D. Increased AMP concentration
NBME-Style Case-Based Questions on the regulation of glycolysis with explanations Read More »
