Written by Prerak Juthani (PEACE Advisor)
The way nucleotides are added are by the fact that the ____ ________ attacks the ___ ______ and displaces pyrophosphate as a leaving group.
a) 5’ hydroxyl, 3’ phosphate
b) 3’ hydroxyl, 3’ phosphate
c) 5’ phosphate, 3’ hydroxyl
d) 3’ hydroxyl, 5’ phosphate
e) 3’ phosphate, 5’ hydroxyl
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a) 5’ hydroxyl, 3’ phosphate
b) 3’ hydroxyl, 3’ phosphate
c) 5’ phosphate, 3’ hydroxyl
d) 3’ hydroxyl, 5’ phosphate
e) 3’ phosphate, 5’ hydroxyl
Press “Read More” to see the answer.
The correct answer is D. The hydroxyl group acts as the nucleophile and the alpha phosphate acts as the electrophile, and this displaces pyrophosphate as the leaving group. This mechanism is ESSENTIAL to your understanding of molecular biology, and the reason why polymerization tends to proceed from the 5′ to the 3′ direction.
This is one of the few things that you need to memorize because it is fundamental to the understanding of the central dogma (DNA -> RNA -> protein)