018- Case Study A child who exhibited an enlarged abdomen was admitted to a clin
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018- Case Study A child who exhibited an enlarged abdomen was admitted to a clinic. She had a history of frequent episodes of weakness and sweating that were eliminated by eating Her growth was somewhat retarded physically in size and weight and her musculature development was poor. She also showed evidence of mental problems such as irritability and confusion. Further examination revealed an enlarged liver. A blood test was done after she had fasted and gave the following results: Glucose -about half of normal Lactate -about 5 times normal Fatty acids- about 3 times normal Ketone bodies-about 13 times normal pH- at 7.30 it is below normal (7.35-7.45) Pyruvate - about 5 times normal Triglycerides - about 2 times normal A liver biopsy was obtained from the extremely enlarged liver. Glycogen and triglyceride levels were high. The attending physician no general, were more severe than other hypoglycemic patients she had seen. ted that the girl's symptoms, in a.) What are the four "control points" or irreversible reactions that use nine different enzymes in carbohydrate metabolism involving glucose, glycogen and pyruvate as starting and stopping points? Glycogen Glucose Pyruvate b.) Assume that there may be a genetic defect causing an enzyme to be relatively inactive. Based solely on the low blood glucose, of these nine enzymes, which five would you test for activity in the liver biopsy? Why did you choose these and not the other four? c.) Of these five enzymes, only two enzymes would really be suspects based on d.) Narrow down your selection to one of these two enzymes and tell why you e.) In light of suspected defect in enzyme activity, explain the results of the blood the liver biopsy results. Which two are these? Why did you pick these? picked the enzyme that you did. test.Explanation / Answer
A)
4 irreversible steps are
1. From glucose to glucose-6-p via hexokinase enzyme
2. From fructose-6-p to fructose1,6-bisphosphate
3.from phosphoenolpyruvate to pyruvate via pyruvate kinase
4. This irreversible steps occur during conversion of glycogen to glucose during low blood glucose via this reaction- glycogen to glucose-1-p via glycogen phosphorylase
B) 5 enzyme test for activity in liver biopsy are
1. Glucose -6-phosphatase
2. Acid maltase
3.alpha1,6-glucosidase
4.phosphorylase
5. Pyruvate kinase
They 5 are selected because they cause specific dis. Like
1. Von girke dis.
2.pompe dis.
3.cori dis.
4.mc ardle dis.
5. Haemolytic anemia
Respectively
C) mainly pyruvate kinase and glucose 6 phosphatse is really be suspects because they present specifically inside liver and easy to detect in blood test.
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