Glycolysis/Gluconeogenesis
What are the inhibitors of pyruvate kinase?
ATP & citrate
What is the rate limiting step of the Kreb’ Cycle?
Isocitrate dehydrogenase
What is the rate limiting step for fatty acid synthesis?
Acetyl CoA carboxylase
What GLUT transporter is predominant in adipose tissue and skeletal tissue?
GLUT 4
What is the NADH/NAD+ ratio in alcoholism?
increased NADH to NAD+ leading to lactic acidosis
Which cells is glucokinase present in?
Liver & pancreatic B cells
Which enzyme complex needs cofactors?
a-ketoglutarate dehydrogenase
Where does B oxidation of very long chain fatty acids occur?
Peroxisome
What concentration gradient do the GLUT transporters follow?
High concentration to low concentration
Which enzyme is deficient in McArdle’s disease?
Glycogen Phosphorylase
A 35 year old woman has acute pancreatitis and give IV fluids. After an ERCP, she can’t have any food and is only allowed some orange juice. Which enzyme is most active?
A. Fructose 1,6 Bisphosphate; B. Glycogen Phosphorylase; C. PFK1; D. Glycerol kinase
(B&B)
D. PFK1
A 30-year-old marathon runner presents with exercise intolerance and cramping. Muscle biopsy shows an accumulation of a substance. There is also a decrease in blood pH. Which substance is likely responsible for this?
A. Isocitrate dehydrogenase; B. a-ketoglutarate dehydrogenas; C. Fumarase; D. Pyruvate dehydrogenase
(ChatGPT)
D. Pyruvate dehydrogenase
A woman has a very healthy lifestyle, she swims 3 times a week and jogs everyday, she avoids processed foods at cooks a well balanced meal. Which of the following is increased?
A. VLDL; B. HDL; C. Triglycerides; D. LDL
(Amboss)
B. HDL
In the presence of insulin, D-glucose transports across the plasma membrane of adipocytes much faster than L-glucose transport. How is glucose transported in terms of mechanism?
A. Simple diffusion; B. Endocytosis; C. Carrier-Mediated Transport; D. Active Transport
(USMLEWorld)
C. Carrier-Mediated Transport
A six month old is brought in for hepatomegaly, hypotonia, and failure to thrive. She has hypoglycemia and ketoacidosis along with hepatic fibrosis. There are multi-branched polysaccharides in the cytoplasm. Which enzyme is deficient?
A. Acid maltose; B. Debranching; C. Pyruvate kinase; D. Glucose-6-phosphatase
(USMLEWorld)
B. Debranching enzyme
A 30 year old presents with confusion and had been binge drinking the past week with little food. He’s had seizures related to alcohol in the past. Glucose is 35 mg/dL and urine is + for ketones. Suppression of what is causing the hypoglycemia?
A. Gluconeogenesis; B. Glycolysis; C. Lipolysis; D. Insulin Sensitivity
(USMLEWorld)
A. Gluconeogenesis
Phosphoenolpyruvate is formed from oxaloacetate in a rxn requiring a specific nucleoside triphosphate as a cofactor. Which reaction synthesizes this cofactor?
A. Oxaloacetate to citrate; B. Isocitrate to a-ketoglutarate; C. Succinyl-CoA to Succinate; D. Succinate to fumarate; E. a-ketoglutarate to succinyl-CoA
(USMLEWorld)
C. Succinyl-CoA to Succinate
This makes GTP
A man presents with worsening fatigue, dark urine, and back pain after having eaten some Egyptian flat bean. There is a deficiency in an enzyme involved in converting G6P to ribulose-5-phosphate. The substance generated from this conversion is is needed for…
A. ADP phosphorylation; B. Fatty acid synthesis; C. Glycogen storage; D. Ketone synthesis; E. Protein degradation
(USMLEWorld)
B. Fatty acid synthesis
A 5 month old presents with poor feeding, and is 5-10%. He has hepatomegaly and hypotonia. He has a gallop rhythm and cardiomegaly. A biopsy shows enlarged lysosomes? Which enzyme is deficient?
A. Acid a-glucosidase; B. Debranching enzyme; C. Galactokinase; D. Glycogen phosphorylase; E. Pyruvate kinase
(USMLEWorld)
A. Acid a glucosidase
A 6 month old presents with lethargy and vomiting. He had a healthy delivery and was breastfed until yesterday where he was given pureed food. He is pale, diaphoretic, and ill-appearing. An aldolase B deficiency is confirmed. What should be removed from his diet?
(USMLEWorld)
Sucrose/Fructose
Researchers are studying energy metabolism in athletes And notice increased lactate levels in sprinters. These high levels regenerate a cofactor for which enzyme?
A. Glycogen phosphorylase; B. G3P dehydrogenase; C. PFK1; D. Pyruvate carboxylase
(Amboss)
B. G3P dehydrogenase
Which cofactor is needed to for the enzymes citrate synthase, a-ketoglutarate, and succinylCoA synthase to work?
A. Thiamine; B. Pantothenic acid; C. Niacin; D. Lipoic Acid
(Amboss)
Pantothenic acid
A researcher is trying to understand the metabolic pathways contributing to obesity and feeds animals a high carb and high protein diet. Liver tissue from the animals shows that B oxidation is inhibited. An increase in which substance is responsible?
A. Acetoacetate; B. Carnitine; C. Citrate; D. Malonyl-CoA; E. NADPH
(USMLEWorld)
Malonyl CoA
An 8 year old presents with exercise intolerance. He has fatigue, muscle pain, and cramps during exercise. Blood samples show no rise in lactate dehydrogenase activity. Glycolysis is inhibited in because of depletion of which substance?
A. AMP; B. Carnitine; C. Citrate; D. NADH; E. NAD+
(USMLEWorld)
E. NAD+
A healthy mine worker is trapped underground for 2 days without having eating the past 30 hrs. Glucose levels are normal. Which reactions is responsible for this?
A. Acetoacetyl CoA to 3-hydroxy-3-methylglutaryl; B. Acetyl CoA to palmitic acid; C. Glucose to G1P; D. Oxaloacetate to PEP
(USMLEWorld)
Oxaloacetate to phosphoenolpyruvate