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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How effectively the helicase works
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What direction the nucleotides are pointing
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Where the RNA primer attaches
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Okazaki’s famous experiment
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Detailed explanation-1: -DNA is always synthesized in the 5’-to-3’ direction, meaning that nucleotides are added only to the 3’ end of the growing strand.
Detailed explanation-2: -The need for accuracy probably explains why DNA replication occurs only in the 5′-to-3′ direction. If there were a DNA polymerase that added deoxyribonucleoside triphosphates in the 3′-to-5′ direction, the growing 5′-chain end, rather than the incoming mononucleotide, would carry the activating triphosphate.
Detailed explanation-3: -DNA polymerase is able to add nucleotides only in the 5’ to 3’ direction (a new DNA strand can be only extended in this direction). It also requires a free 3’-OH group to which it can add nucleotides by forming a phosphodiester bond between the 3’-OH end and the 5’ phosphate of the next nucleotide.
Detailed explanation-4: -One new strand, which runs 5’ to 3’ towards the replication fork, is the easy one. This strand is made continuously, because the DNA polymerase is moving in the same direction as the replication fork. This continuously synthesized strand is called the leading strand.