Metabolism US Medical PG Flashcards - Medical Study Cards
Master Metabolism with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Metabolism Flashcard Deck - 10 Cards
Flashcard 801: What are the followings in relation to gluconeogenesis?
-Acetyl CoA
-Alanine
-Citrate
-Fructose 2,6-bisphosphate
-Lactate
-Oxaloacetate
Answer: Acetyl-CoA: will stimulate pyruvate carboxylase to convert pyruvate to oxaloacetate (the 1st step of gluconeogenesis).
-Alanine: could convert to pyruvate and back in transaminase reaction, when it's converted to pyruvate it could inhibit pyruvate kinase to create pyruvate to prevent glycolysis while allowing gluconeogenesis to take place.
-Citrate: 1st step in kreb cycle. Important positive regulator of acetyl coa carboxylase to create glucose. It's important for fatty acid synthesis.
-Fructose 2,6-bisphosphate: high level of it stimulate phosphofructokinase-1, thus stimulate glycolysis. Low levels of it stimulate gluconeogenesis.
-Lactate: important source of carbon atoms for glucose synthesis. Lactate formed in contracting muscles, it is release in the bloodstream and go to the liver to converted back to glucose.
-Oxaloacetate: high levels of it will decrease activity of pyruvate carboxylase preventing gluconeogenesis.
Flashcard 802: 52 y/o woman comes with skin rash that worsens with sun exposure.
-Her family says: she has become irritable, hostile, and has had episodes of disorientation.
-Further questionning revelas poor nutritional intake and intermittent diarrhea.
-Physical Exam: well-demarcated, hyperpigmented, scaly rash on hands, forarms, & upper chest.
-Cause of symptoms is due to lack of precursor vitamin for synthesis of NAD+ coenzyme.
-This pathway will most likely use which compound as a precursor?
Answer: Tryptophan
due to Niacin deficiency ( Diarrhea, dermatitis, dementia)
Flashcard 803: True or False
Some patients with porphobilinogen deaminase deficiency could be asymptomatic for Acute intermittent porphyria
Answer: True
because porphobilinogen deaminase deficiency is not sufficient enough to cause symptoms.
Flashcard 804: In what reaction does the followings amino acids participate in?
-Phenylalanine
-Valine
-Asparagine
-Histidine
-Proline
-Lysine
Answer: Pheynylalanine: converted to tyrosine by phenylalanine hydroxylase. Deficiency of Phenylalanine dehydroxylase lead to PKU.
-Valine: Part of the "Met Threonine Valle", they synthesize propionyl-CoA which will convert to methylmalonyl coa by propionyl carboxylase, then methylmalonyl coa will converted to succinyl CoA (TCA cycle) by methylmalonyl CoA mutase.
-Asparagine: can be converted to aspartate by asparaginase. Leukemic cells loves asparagine to survive. Thus L-asparaginase usually works as an antineoplastic agent by lowering circulating asparagine levels.
-Histidine: could be converted to histamine, (H2) acid or H1(allergies) release by Mast cells which could be presented in hypersensitivity type 1 (allergic reaction).
-Proline: could use as a transaminase amino acids which means it could convert to alpha ketogluterate then to glutamate (vit. B6 as cofactor). ("Transaminase PG": Proline to glutamate). Can also get hydroxylize by Vit C.
-Lysine: Could get hydrolylize by Vit. C. Lysine is strictly Ketogenic. which means it will not convert to another amino acid (ending with ....-ate).
Flashcard 805: What are the followings in relation to neutralizing toic molecules?
-Cytochrome oxidase
-Cytochrome p450
-Myeloperoxidase
-NADPH
-Superoxide dismutase
Answer: Cytochrome oxidase: final component in electron transport chain, convert molecular oxygen to water. Help synthesizing ATP.
-Cytochrome p450: metabolize endogenous toxins as well as drugs. can lead hepatotoxicity in certain drugs.
-Myeloperoxidase: found in neutrophils, could cause oxidative damage to host cells.
-NADPH: help phagocytic cells destroy bacteria. Deficiency could lead to chronic granulomatous disease, where catalase positive organisms can't get destroy even after being phagocyte by WBC.
-Superoxide dismutase: neutrilizes reactive oxygen species, preventing cell injury and prevent acute compartment syndrome secondary to reperfusion injury.
Flashcard 806: A 5 month old boy comes with poor feeding.
-Physical exam: hepatomegaly and hypotonia in all 4 limbs.
-Cardiac auscultation: gallop rhythm
-Chest Xray: Severe cardiomegaly
-Muscle biopsy: Enlarged lysosomes containing periodic acid-schiff (PAS)-positive material.
-Which enzymes is most likely deficient in this patient?
Answer: Acid alpha-glucosidase (alpha 1,4 glucosidase deficiency) or Acid maltase deficiency
due to Pompe disease (Very Poor Carbs Metabolism)
Accumulation of glycogen in lysosomal vesicles.
Present with: Normal glucose levels, severe cardiomegaly.
Flashcard 807: A newborn comes with lethargy, vomiting, and hypotonia during fist few days of life.
-Lab: metabolic acidosis with large anion gap, ketosis, & hypoglycemia.
-Concentration of propionic acid is increase in the plasma and urine.
-Metabolism of which amino acids contributes to this patient's condition?
Answer: Valine
Others: "Met Threonine ValLe" (Methionine, Threonine, Valine, Isoleucine), odd chain fatty acids, cholesterol.
due to deficiency of propionyl-CoA carboxylase, which usually convert propionyl CoA to methylmalonyl CoA which will be converted to succinyl CoA (TCA cycle), by methylmalonyl CoA mutase with the help of vit. B12 as a cofactor.
Flashcard 808: What are the followings substances are associated with in relation to cofactors or chemical reaction?
-Biotin
-Folic acid
-Niacin
-Pyridoxine
-Riboflavin
-Thiamine
Answer: Biotin: Vit B7, cofactor for carboxylases enzymes. Ex: Pyruvate carboxylase.
-Folic Acid: Vit B9, cofactor for Nucleic acid synthesis. Deficiency lead to megaloblastic anemia, due to lack of division of cells to turn to normal size RBC but instead their radius becomes bigger.
-Niacin: Vit B3, cofactor for dehydrogenase enzymes (NAD+ & NADP+). Deficiency leads to DDD (pellegra): Diarrhea, Dementia, Dermatitis.
-Pyridoxine: Vit B6, cofactor for transaminase, which means conversion of: amino acids ---> a-keto acid ---> amino acid. Ex: Glutamate to oxaloacetate then to aspartate. Deficiency could lead to homocystinuria.
-Riboflavin: Vit B2, are use in dehydrogenase reaction involving FMN and FAD (Flavin MN or Flavin AD).
-Thiamine: Vit B1, cofactor for dehydrogenase enzymes in Transketolase dehydrogenase. Ex: .....Keto..... Dehydrogenase.
Flashcard 809: A 2 y/o boy is being evaluated for failure to thirve and developmental delay.
-Past Medical history: recurrent ear infection since age 6 months.
-Physical Exam: coarse facial features, corneal clouding, hepatosplenomegaly and restricted joint mobility.
-Mass spectrometry analysis: Deficient phosphorylation of mannose residues on certain glycoproteins in the golgi apparatus.
-Normally, these proteins are most likely to be transported to which cellular locations?
Answer: Lysosome
due to Inclusion cell (I Cell) disease
which is a defect in protein targetting due to lack of phosphorylation of mannose residues in proteins, which causes lack of protein in lysosome, lead to accumulation of cells debris without degradation in lysosome.
Symptoms: Coarse facial features, corneal clouding, failure to thrive, & cognitive deficits in 1st year of life.
Flashcard 810: A researcher are investigating the relationship between glucose transporters and insulin concentration in various cells & tissues.
-Data are collected in the graph below.
-The graph shows number of glucose transporters found on the surface of 2 types of cells (circles versus triangles) compared to serum insuli concentration.
Which cells types are most likely represented by the circles and triangles?
Answer: Skeletal muscle and renal cells (any other cells as long as it's not adipocytes or skeletal muscle cells)
Circle: Skeletal muscle or adipocytes (insulin dependent). (GLUT 4 receptor)
Triangles: Any other cells (insulin independent).
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