Question on AAMC Scored Test

[medgirl94]

If anyone has done this, can someone explain why #46 on Bio/Biochem is D and not C.

The explanation on the answers (which is correct) says that the 5' nucleotide bears the phosphate group and the 3' nucleotide bears the hydroxyl group. If this were the case, I would think that the phosphodiester bond would involve the phosphate group of the thymine and the sugar of the adenine, but that does not seem to be the case.

Thanks a bunch!

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[azucker20]

the number refers to the carbon number so on the adenine the 5' carbon has the phosphate which binds to the 3' hydroxyl group of thymine...hope this makes sense

 

[exacto]

Just type in phosphodiester bond in google and the first pic will show you where the bonds connect....pictures are so much more useful for this kind of thing...

 

[medgirl94]

Thanks guys!