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High Yield Warm-up Questions: Biochemistry, Part B GENERAL PRINCIPLES SET 2: BIOCHEMISTRY, PART B A 5-month-old infant, with a protruding abdomen, was brought to the hospital after having a convulsion The child had an enlarged liver, which when biopsied later, contained large amounts of glycogen Upon examination, there were no apparent abnormalities in the other organs However, lab tests revealed severe hypoglycemia, hyperuricemia, and lactic acidosis, which were other manifestations What is the primary biochemical defect in this disease? Explain the biochemical basis for the enlarged liver and why the muscle showed no abnormality in this infant Explain whether or not there would be fasting hyperlipidemia in this infant An obese patient volunteered to go on a starvation diet as part of a study Blood samples were taken and analyzed for several weeks following the fast Early in the fast, blood glucose dropped slightly, but then maintained at 4.5mM Soon after the start of the fast, blood levels of fatty acids rose, whereas cholesterol levels did not After day of fasting, the pH of the blood dropped to 7.35 The blood concentrations of ketone bodies and alanine began to rise The pathways needed to maintain blood glucose levels are glycogen breakdown and gluconeogenesis How does the liver know how to breakdown its stored glycogen and conduct gluconeogenesis during fasting/starvation conditions? 1 High Yield Warm-up Questions: Biochemistry, Part B Another pathway needed to provide the body with fuel during starvation is lipolysis in adipose tissue How adipocytes know to mobilize triglycerides at the appropriate time of fasting, whereas blood cholesterol levels not change? Ketone body synthesis is not hormonally regulated How does the liver know to conduct ketone body formation during starvation? A 70-year-old woman with a history of celiac disease is brought to the physician for a follow-up examination She was complaining about her fingers having a tingling sensation Laboratory studies reveal that the woman’s hemoglobin level is 11.9 g/dL and a hematocrit of 30% She also has elevated homocysteine in the bloodstream A peripheral blood smear shows numerous enlarged red blood cells and some neutrophils with hypersegmented nuclei The physician determines that the woman is deficient in vitamin B12 Besides vitamin B12, what other vitamin deficiencies can result in elevated homocysteine in the bloodstream? What is the connection of the woman’s history of celiac disease and her deficiency in vitamin B12? Why does deficiency of vitamin B12 result in enlarged red blood cells? High Yield Warm-up Questions: Biochemistry, Part B A 7-month-old girl presents with motor and cognitive developmental delays, poor feeding behavior, and general failure to thrive A laboratory urinalysis showed high levels of orotic acid and a blood test revealed anemia, which was found to be megaloblastic There was no evidence of hepatomegaly or splenomegaly The pediatrician started the infant on a dietary regimen consisting of vitamin B6, vitamin B12, folate, and iron, but the regimen did not improve the infant’s symptoms The condition was resolved by feeding the patient a diet high in uridine 10 What is the biochemical difference between orotic acid and uridine? 11 What enzyme/pathway is likely to be deficient and responsible for the infant’s symptoms and why did the first dietary regimen not improve the infant’s symptoms? 12 Explain the reasons for both the high levels of orotic acid and the megaloblastic anemia and why uridine resolved the patient’s symptoms? These question sets are intended to be completed before viewing the High Yield course lectures Video explanations can be found on the Warm-up Questions page within the online High Yield course For further review of the topics covered in this set, refer to the following lectures: Biochemistry: • Overview of Metabolism: CHO • Lipid Metabolism • Amino Acid Metabolism • Purines and Pyrimidines 3 ... disease and her deficiency in vitamin B1 2? Why does deficiency of vitamin B1 2 result in enlarged red blood cells? High Yield Warm-up Questions: Biochemistry, Part B A 7-month-old girl presents with... delays, poor feeding behavior, and general failure to thrive A laboratory urinalysis showed high levels of orotic acid and a blood test revealed anemia, which was found to be megaloblastic There was... Yield Warm-up Questions: Biochemistry, Part B Another pathway needed to provide the body with fuel during starvation is lipolysis in adipose tissue How adipocytes know to mobilize triglycerides at
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