THE MOLECULAR BASIS OF INHERITANCE
DNA REPLICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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to the 5’OH group of the previous deoxyribose sugar
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to the 5’OH group of the previous phosphate group
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to the 3’OH group of the previous deoxyribose sugar
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to the 3’OH group of the previous phosphate group
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Detailed explanation-1: -As new nucleotides are added to a strand of DNA or RNA, the strand grows at its 3’ end, with the 5′ phosphate of an incoming nucleotide attaching to the hydroxyl group at the 3’ end of the chain.
Detailed explanation-2: -DNA polymerases can only add nucleotides to the 3’ end of an existing DNA strand. (They use the free-OH group found at the 3’ end as a “hook, ” adding a nucleotide to this group in the polymerization reaction.)
Detailed explanation-3: -(A) The phosphate group of the incoming nucleotide forms a bond with the 3’ end of the sugar on the growing strand. Specifically, the 5’ phosphate group of the incoming new nucleotide forms a phosphodiester bond with the 3’-OH group of the last nucleotide on the growing strand.
Detailed explanation-4: -Thus, they also depend on a primase, which generally assembles a short RNA primer to provide a 3′-OH that can be extended by the replicative DNA polymerase.
Detailed explanation-5: -The primer provides a 3’ hydroxyl group onto which the DNA polymerase adds the precursors of DNA, the nucleotides. When nucleotides are added to the 3’ end of the primer or the new DNA strand, a bond is formed between the 3’ hydroxyl group of the primer/new DNA and the 5’ phosphate group of the nucleotide.