MCBG Biochem missed qs exam 2 Flashcards
A 57-year-old alcoholic man is brought to the emergency department in a state of global confusion, psychosis, ataxia, peripheral edema, and tachycardia. On examination, opthalmoplegia and polyneuropathy are also noted. Which of the following vitamins is most likely, deficient in this patient? A. Vitamin B1 B. Vitamin B2 C. Vitamin B3 D. Vitamin B6 E. Vitamin B12
A. Vitamin B1 Vit B1 deficiency presents with: Dementia (global confusion and psychosis) Ataxia Wet berry edema (peripheral edema) Opthalmoplegia (paralysis of eye muscles) See this in chronic alcoholics
A 21-year-old homeless man presents to your clinic complaining of generalized weakness. He reports that he has only been eating 3 to 4 days per week when he is able to attend meals at a local soup kitchen. You noticed that he has inflammed and cracked skin at the corners of his lips, magenta tongue, and seborrheic (“greasy”) dermatitis. Further physical examination reveals vascularization of his corneas. Which of the following vitamins is most likely, deficient in this patient? A. Vitamin B1 B. Vitamin B2 C. Vitamin B3 D. Vitamin B6 E. Vitamin B12
B. Vitamin B2 Inflamed and cracked skin at corners of mouth=vit B2 deficiency B2 deficiency presentation: inflamed and cracked skin at corners of mouth magenta tongue seborrheic (greasy) dermatitis
Consider a 40-year-old man who has just initiated a 24 h fast. Which of the following cofactors are necessary so that his blood glucose levels can be kept constant? A. B6, biotin, and vitamin D B. B6, niacin, and vitamin D C. B6, biotin, and niacin D. Biotin, niacin, and B12 E. B6, niacin, and vitamin K
C. B6, biotin, and niacin
A woman 7 months pregnant with her first child develops anemia. Lab evaluation indicates increased mean corpuscular volume, hypersegmented neutrophils, and altered morphology of several other types. The most likely underlying cause of this woman’s anemia is A. folate deficiency B. iron deficiency C. G6P dehydrogenase deficiency D. cyanocobalamin (B12) deficiency E. lead poisoning
A. folate deficiency
A woman 7 months pregnant with her first child develops anemia. Lab evaluation indicates decreased mean corpuscular volume. The most likely underlying cause of this woman’s anemia is A. folate deficiency B. iron deficiency C. G6P dehydrogenase deficiency D. cyanocobalamin (B12) deficiency E. lead poisoning
B. iron deficiency Pregnant lady w/ microcytic anemia= iron deficiency decreased mean corpuscular volume=microcytic anemia
A 30-year-old vegetarian presents to his physician complaining of diminished sensation in his lower extremeties. He has not eaten meat for the past 15 years. A complete analysis of his blood sample reveals hypersegmented neutrophils and elevated mean corpuscular volume, and hyperammonemia. Physical exam reveals neurological problems which confirm you suspicion. You suspect that his neurological impairment symptoms could be the result of a combination of the hyperammonemia and malformation of myelin sheath surrounding his neuronal cells in the CNS. You quickly ask for lab analysis of his urine sample. Which of the following findings would be expected from the urinalysis? A. Argininosuccinic aciduria B. Methylmalonic aciduria C. Hemoglobinuria D. Cystinuria E. Propionic aciduria
B. Methylmalonic aciduria L-MMA => succinyl coA requires B12. L-MMA is structurally similar to malonyl coa, so it can go and interfere in FA synthesis, leading to malformation of myelin sheath surrounding the neuronal cells.
A group of activists was concerned about the indiscriminate felling of trees in the rain forest area of Brazil. They decided to protest this by going on a hunger strike in Washington D.C. Despite the fact that they had last eaten 24 hours earlier, they seemed well. At this time which of the following enzymes has become reponsible for helping to maintain blood glucose level?
A. Glycogen synthase
B. Acetyl-CoA carboxylase
C. Glycogen phosphorylase
D. Pyruvate carboxylase
E. Glucose-6-phosphate dehydrogenase
D. Pyruvate carboxylase
First 24 hours=Glycogenolysis provides glucose
At 24 hour mark gluconeogenesis takes over and tails off at 40 hour mark
At 40 hour mark see ketogenesis and then once that’s over utilization of non-vital glucogenic amino acids from muscle tissuee
Gluconeogenesis enzymes:
Pyruvate acrboxylase
PEP carboxy kinase (PEPCK)
Phosphoglycerate kinase
Fruc 1,6 bisphosphatase
gluc 6-phosphatase
A breast-fed infant begins to vomit frequently and lose weight. Several days later, she is jaundiced, her liver is enlarged, and cataracts are noticed in her lenses. These symptoms are most likely caused by deficiency of
A. lactase
B. galactokinase
C. aldolase B
D. glucose-6-phosphatase
E. galactose-1-P uridyltransferase
E. galactose-1-P uridyltransferase. Patient has galactosemia Type I, Classical galactosemia
It must be gal-1-P uridyltransferase b/c of jaundice.
Gal-1-p accumulates causing liver damage, leading to accumulation of unconjugated bilirubin which causes jaundice.
If it said cataracts only, then answer would be B. galactokinase deficiency
A 20-year-old man is taken to the university clinic to determine the cause of recurring hyperlipidemia, proteinuria and anemia. Fasting blood tests reveal slightly elevated concentrations of unesterified cholesterol and phosphatidylcholine (lecithin). The patient is given 100 gram chocolate bar and blood lipid levels are monitored hourly. Results reveal significantly increased levels of unesterified cholesterol and phosphatidylcholine (lecithin) for extended periods. A deficiency of which of the following proteins is most likely to be associated with the observations in this pateint?
A. Acyl-CoA:cholesterol acyltransferase (ACAT)
B. ApoA-1
C. ApoB-48
D. ApoB-100
E.Lipoproteinlipase
B. ApoA-1.
adipose isozyme- is associated with epithelial cells, it has high km
skeletal muscle tissue isozyme has low km
Sr-A1 on macrophages
Sr-B1 is on stereogenic tissues.
APo-A1 activates LCAT
Lcat catalyzes conversion of PC and Lecithin to a cholesterol ester
Researchers are developing a new drug to treat type IV hyperlipidemia. The drug would be most useful in treating this disorder if it acted in which of the following ways?
A. Increase apoB-100 synthesis
B. Increase leptin synthesis in the adipose tissue
C. Inhibited capillary lipoprotein lipase
D. Inhibited cholesterol ester transfer protein
E. Inhibited apoE synthesis
B. Increase leptin synthesis in the adipose tissue
Leptin is an appetite suppressant
Hyperlipidemias:
Type I= LPL deficiency
Type II= LDL receptor (ApoB-100 receptor) deficiency= hypercholesterolemia
Type III=abnormal ApoE, presents w/ palmar xanthomas
Type IV= accumulation of LDL; LDL comes from excess glucose and carbs that leads to induction of FA synthesis. Leptin suppresses apetite. Leptin is produced in adipose tissue, and limits carb intake so pt. has decr. LDL production.
Type V is elevation of vLDL and chylomicrons, it’s seen in diabetic individuals, esp. Type I diabetics. Insulin is needed to induce LPL to hydrolyze chylomicron and vLDL
Which ONE of the following is NOT involved in the production of arachidonic acid (C20:4 (5, 8, 11, 14) from lecithin-containing dietary fat with linoleic acid (C18:2 (9,12) at the sn-2 (carbon 2 of the backbone) of lecithin, in humans?
A. C4-desaturase
B. C5-desaturase
C. C6 desaturase
D. Phospholipase A2
E. Malonyl-CoA
A. C4-desaturase
A 2-yr-old patient
enlargement, and skeletal abnormalities. Assay of lysosomal levels of alpha-L-iduronidase indicated only 10% of normal values, but high circulating levels of alpha-L-iduronidase activity. Further analyses indicated the absence of glycosaminoglycans in her urine samples. These data are sufficient to establish diagnosis of her disease as
A. Hunter syndrome
B. Hurler syndrome
C. Hurler-Scheie syndrome
D. I-cell disease
E. Morquio syndrome
D. I-cell disease
Not B or C b/c there was alpha-L-iduronidase present inthe blood.
I-cell disease is due to lysosomal enzymes not going to lysosome b/c there is deficency enzyme that puts mannose-6P tag on enzymes destined for the lysosome in the golgi apparatus. With out their tags, the lysosomal enzymes are released and just float arount in the blood, and few if any reach lysosome.
Six hours after birth, a small-for-gestational-age newborn was found to have blood glucose of 41 mg/dL. The infant was otherwise normal on physical examination. Blood glucose immediately increased after the infant started suckling. However between feedings, the infant had bouts of hypoglycemia and mild lactic acidosis. Consistent with hypoglycemia, the blood glucagon level was elevated. Infusion of glycerol increased blood glucose, but several glucogenic amino acids did not. Which of the following enzymes is most likely deficient in this infant?
A. Fructose-1,6-phosphatase
B. Glucose-6-phosphatase
C. Glycogen phosphorylase
D. Phosphoenolpyruvate carboxykinase (PEPCK)
E. Pyruvate kinase
D. Phosphoenolpyruvate carboxykinase (PEPCK).
Infusion of glucogenic amino acids didn’t work showing the issue was with PEPCK b/c PEPCK catalyzes conversion of OAA to PEP, so amino acids could be converted to OAA, but it wouldn’t be converted to PEP so pathway could continue. Infusion of glycerol worked b/c it can be converted to 3-phosphoglycerate bypassing the PEPCK step so glucose can be produced.
