UWorld Biochem Exam Real Questions
100% Solved Correct
Hereditary Fructose Intolerance - Answers -✔✔ Aldolase B deficiency.
Symptoms: vomiting and hypoglycemia when fructose introduced to diet. Failure to
thrive, jaundice, and hepatomegaly.
1g of protein or carbohydrate = ? kcal
1g of fat = ? kcal - Answers -✔✔ protein & carbs = 4 calories
fat = 9 calories
Wernicke-Korsakoff syndrome - Answers -✔✔ Organic brain syndrome resulting from
prolonged heavy alcohol use, involving confusion, unintelligible speech, and loss of
motor coordination. It may be caused by a deficiency of *thiamine*, a vitamin
metabolized poorly by heavy drinkers.
Diarrhea, dementia, and dermatitis are indicative of what disease? What enzymes are
impaired? - Answers -✔✔ pellagra - caused by niacin (B3) deficiency. Enzymes
impaired are the dehydrogenases.
What enzymes are encoded by the lac operon? - Answers -✔✔ beta-galactosidase,
permease, and transacetylase
classic example of polycistronic mRNA - Answers -✔✔ the lac operon in E. coli
Beriberi - Answers -✔✔ Thiamine (B1) deficiency. Causes peripheral neuropathy,
cardiomyopathy, high-output CHF, peripheral edema, and tachycardia. (Wet beriberi
includes the cardiac symptoms)
The ammonia buffer system helps to eliminate excess hydrogen ions by - Answers -✔✔
metabolism of glutamine to glutamate in renal tubular cells, generating ammonium that
is excreted in the urine
Which dietary sugar is metabolized the fastest? - Answers -✔✔ Fructose.
Phosphorylated in the liver to F-1-P, which bypasses the RLS of PFK-1 in glycolysis.
Tagging with phosphorylated mannose residues marks proteins for delivery to... -
Answers -✔✔ the lysosome
I-cell disease - Answers -✔✔ Symptoms: Coarse facial features, {{clouded corneas,
restricted joint movement,}} high plasma levels of lysosomal enzymes. Fatal in
childhood.
Lab Values: {{Lysosomal enzymes secreted outside the cell; ghost lysosomes.}}
, Pathophysiology: *Lysosomal storage disease; {{failure of mannose-6-phosphate
addition}} which is required to traffic proteins to lysosomes.
Ornithine transport to the mitochondria is necessary for what cycle? What happens in
deficiencies? - Answers -✔✔ Urea cycle. Ornithine transport deficiencies prevent
conversion of ammonia (byproduct of protein metabolism) to urea for excretion. Leads
to buildup of ammonia in serum (causing vomiting, lethargy, seizures, and cerebral
edema).
What metabolite controls the balance between glycolysis and gluconeogenesis? Which
enzymes does it effect? How do insulin and glucagon play in? - Answers -✔✔
*Fructose-2,6-bisphosphate* is metabolite that controls balance between glycolysis and
gluconeogenesis (inverse control of fructose-1,6-bisphosphatase and
phosphofructokinase-1)
Insulin- "turns off glycolysis", increases levels of F-2,6-BP by activating PFK-2
Glucagon- "turns on glycolysis," decreases levels of F-2,6-BP by activating F-2,6-BPase
Maple Syrup Urine Disease - Answers -✔✔ is caused by a defect in alpha keto acid
dehydrogenase, leading to an inability to degrade branched amino acids (isoleucine,
leucine, and valine "I Love Vermont maple syrup, the trees have Branches). This illness
classically results in poor feeding and dystonia as well as the maple syrup scent (burnt
sugar) in the patients urine after first couple days of life.
Bruising mechanism. Colors: blue/purple - green - yellow - Answers -✔✔ heme released
- heme oxygenase converts it to biliverdin - biliverdin reductase converts it to bilirubin
In disorders of the urea cycle leading to hyperammonemia, which AA is essential in the
patient? - Answers -✔✔ arginine
Intron labeling at the 5' and 3' ends - Answers -✔✔ 5'-GU, 3'-AG
What two deficiencies lead to hemolytic anemia under oxidative challenge? - Answers -
✔✔ 1) G6PD deficiency (X-linked, inability to form NADPH, bite cells on smear)
2) Glutathione reductase deficiency (prevents reduction of glutathione, so cannot use
NADPH)
heterozygous familial hypercholesterolemia - Answers -✔✔ autosomal dominants
defect in LDL receptor causing high LDL levels
Vitamin B12 deficiency - Answers -✔✔ -Takes 4-5 years to develop due to large liver
stores.
-B12 (cobalamin) found only in animal products
-Due to malabsorption, intrinsic factor or terminal ileum, or insufficient intake.
100% Solved Correct
Hereditary Fructose Intolerance - Answers -✔✔ Aldolase B deficiency.
Symptoms: vomiting and hypoglycemia when fructose introduced to diet. Failure to
thrive, jaundice, and hepatomegaly.
1g of protein or carbohydrate = ? kcal
1g of fat = ? kcal - Answers -✔✔ protein & carbs = 4 calories
fat = 9 calories
Wernicke-Korsakoff syndrome - Answers -✔✔ Organic brain syndrome resulting from
prolonged heavy alcohol use, involving confusion, unintelligible speech, and loss of
motor coordination. It may be caused by a deficiency of *thiamine*, a vitamin
metabolized poorly by heavy drinkers.
Diarrhea, dementia, and dermatitis are indicative of what disease? What enzymes are
impaired? - Answers -✔✔ pellagra - caused by niacin (B3) deficiency. Enzymes
impaired are the dehydrogenases.
What enzymes are encoded by the lac operon? - Answers -✔✔ beta-galactosidase,
permease, and transacetylase
classic example of polycistronic mRNA - Answers -✔✔ the lac operon in E. coli
Beriberi - Answers -✔✔ Thiamine (B1) deficiency. Causes peripheral neuropathy,
cardiomyopathy, high-output CHF, peripheral edema, and tachycardia. (Wet beriberi
includes the cardiac symptoms)
The ammonia buffer system helps to eliminate excess hydrogen ions by - Answers -✔✔
metabolism of glutamine to glutamate in renal tubular cells, generating ammonium that
is excreted in the urine
Which dietary sugar is metabolized the fastest? - Answers -✔✔ Fructose.
Phosphorylated in the liver to F-1-P, which bypasses the RLS of PFK-1 in glycolysis.
Tagging with phosphorylated mannose residues marks proteins for delivery to... -
Answers -✔✔ the lysosome
I-cell disease - Answers -✔✔ Symptoms: Coarse facial features, {{clouded corneas,
restricted joint movement,}} high plasma levels of lysosomal enzymes. Fatal in
childhood.
Lab Values: {{Lysosomal enzymes secreted outside the cell; ghost lysosomes.}}
, Pathophysiology: *Lysosomal storage disease; {{failure of mannose-6-phosphate
addition}} which is required to traffic proteins to lysosomes.
Ornithine transport to the mitochondria is necessary for what cycle? What happens in
deficiencies? - Answers -✔✔ Urea cycle. Ornithine transport deficiencies prevent
conversion of ammonia (byproduct of protein metabolism) to urea for excretion. Leads
to buildup of ammonia in serum (causing vomiting, lethargy, seizures, and cerebral
edema).
What metabolite controls the balance between glycolysis and gluconeogenesis? Which
enzymes does it effect? How do insulin and glucagon play in? - Answers -✔✔
*Fructose-2,6-bisphosphate* is metabolite that controls balance between glycolysis and
gluconeogenesis (inverse control of fructose-1,6-bisphosphatase and
phosphofructokinase-1)
Insulin- "turns off glycolysis", increases levels of F-2,6-BP by activating PFK-2
Glucagon- "turns on glycolysis," decreases levels of F-2,6-BP by activating F-2,6-BPase
Maple Syrup Urine Disease - Answers -✔✔ is caused by a defect in alpha keto acid
dehydrogenase, leading to an inability to degrade branched amino acids (isoleucine,
leucine, and valine "I Love Vermont maple syrup, the trees have Branches). This illness
classically results in poor feeding and dystonia as well as the maple syrup scent (burnt
sugar) in the patients urine after first couple days of life.
Bruising mechanism. Colors: blue/purple - green - yellow - Answers -✔✔ heme released
- heme oxygenase converts it to biliverdin - biliverdin reductase converts it to bilirubin
In disorders of the urea cycle leading to hyperammonemia, which AA is essential in the
patient? - Answers -✔✔ arginine
Intron labeling at the 5' and 3' ends - Answers -✔✔ 5'-GU, 3'-AG
What two deficiencies lead to hemolytic anemia under oxidative challenge? - Answers -
✔✔ 1) G6PD deficiency (X-linked, inability to form NADPH, bite cells on smear)
2) Glutathione reductase deficiency (prevents reduction of glutathione, so cannot use
NADPH)
heterozygous familial hypercholesterolemia - Answers -✔✔ autosomal dominants
defect in LDL receptor causing high LDL levels
Vitamin B12 deficiency - Answers -✔✔ -Takes 4-5 years to develop due to large liver
stores.
-B12 (cobalamin) found only in animal products
-Due to malabsorption, intrinsic factor or terminal ileum, or insufficient intake.
