SSC
BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Where are free nucleotides added to a newly growing strand?
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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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Explanation:
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: -When nucleotides are incorporated into DNA, adjacent nucleotides are linked by a phosphodiester bond: a covalent bond is formed between the 5’ phosphate group of one nucleotide and the 3’-OH group of another (see below). In this manner, each strand of DNA has a “backbone” of phosphate-sugar-phosphate-sugar-phosphate.
Detailed explanation-3: -DNA polymerase is the enzyme that catalyzes the addition of a nucleotide onto the 3’ end of a growing DNA strand.
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