Lim
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The LDL-cholesterol of a baby with known familial hypercholestrolemia is 605mg/dl although the baby's plasma triglyceride levels are normal. Molecular genetic studies of cells isolated from the baby indicate 10% LDL receptor activity and 10% of the normal amount of LDL receptors on the cell surface. Further in vitro studies with the receptor indicate a normal equilibium between bound and free LDL at pH = 7.0, but an unusually high amount of bound LDL at pH = 6.0. Which of the following mutations best explain these data?
A. Complete blockade of the transport of the LDL receptor between the endoplasmic reticulum and the Golgi appratus
B. Increased lysosomal degradation of the LDL receptor
C. Non-functional promoter in the LDL receptor gene
D. Poor interation with the coated pit,resulting in poor internalization of the LDL
E. Reduced binding of LDL to its receptor
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| lilla
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answer is B.
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| Lim
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yes,your're right,lilla.
can you explain why it is?
the baby has over 600 mg/dl,so it has homozygous type.(LDL receptor def.)
and...hm...does it have low pH? not inside of cell and outside? what does this mean?
help with this,please.
thanks in advance.
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| lilla
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sorry, Lim, I just geussed from PH. b/c:all lysosomal enzymes are acid hydrolases, with optimal activity at a PH of opproximately5.0.
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