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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5’ to 3’ direction
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3’ to 5’ direction
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3’ to 3’ direction
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5’ to 5’ direction
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Detailed explanation-1: -The DNA double helix is anti-parallel, which means that the 5’ end of one strand is paired with the 3’ end of its complementary strand (and vice versa).
Detailed explanation-2: -DNA is always synthesized in the 5’-to-3’ direction, meaning that nucleotides are added only to the 3’ end of the growing strand. As shown in Figure 2, the 5’-phosphate group of the new nucleotide binds to the 3’-OH group of the last nucleotide of the growing strand.
Detailed explanation-3: -DNA is a right-handed helix. Normal B-DNA, as first described by Watson and Crick, is a right-handed helix. GC-rich DNA can also exist in a form known as Z-DNA, which forms a left-handed helix.
Detailed explanation-4: -Each ring is joined to its neighbouring phosphate groups by bonds on 3’ and 5’. As all the sugar rings in a strand face the same direction, it is possible to tell which end of a strand is which – the 5’ end, where the fifth carbon is nearest the end of the chain, or the 3’ end.