blueocean
Forum Senior
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A decrease in the level of hem leads to a reduction in globin synthesis in reticulocytes.Which of the following best explains this phenomenon:
A. RNA polymerase activity is decreased by the low hem
B. eIF2 become phosphorylated, reducing the level of activity
C. Hem normally activates peptidyltransferase in reticulocytes
D. A tRNA degrading enzyme is active in the absence of hem
E. A heme-controlled phosphatase dephosphorilates cap-binding factor which prevent5s recognit5ion of globin mRNA by the ribosome
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| blueocean
Forum Senior
Topics: 15
Posts: 195
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guys, somebody can answer???
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| tinabg
Forum Newbie
Topics: 2
Posts: 22
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I found it! It's B.
In heme deficiency, inhibition of protein synthesis correlates with the activation of heme-regulated eIF-2 kinase (HRI), which blocks the initiation of protein synthesis by phosphorylating eIF-2.
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| blueocean
Forum Senior
Topics: 15
Posts: 195
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thank you!!!!!!!!!!!!!!!
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| drpkaur
Forum Guru
Topics: 196
Posts: 810
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what in lippincott says that heme stimulates overall translation by preventing the phosphorylation of eukaryotic intiation factor eIF-2 ,which is only active in its unphosphorylated form..further it says that the translation of some mRNA molecules is regulated by the binding of regulatory proteins which sometimes block translation( e.g.of ferritin mRNA) and sometimes stabilize the mRNA to extend its lifetime(e.g.of transferrin receptor mRNA)..
what does this mean??any details..
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| fox
Forum Guru
Topics: 70
Posts: 727
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I think its A based on drpkaur's expln
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