Question

What is incorrect about the above figure representing DNA replication?
A. The direction of DNA replication in strand (i)

B. The direction of DNA replication in strand (ii)
C. Discontinuous replication of strand (i)
D. Discontinuous replication of strand (ii)

Answer 1

Hint: DNA polymerase can polymerize nucleotides only in 5′→3′ direction on 3′→5′ strand due to the adding them at the 3′ end. Since the two strands of DNA run in antiparallel paths, the two templates furnish different ends for replication.

Complete answer: When a cell divides, it is significant that each daughter cell obtains a comparable copy of the DNA. This is achieved by the procedure of DNA replication. The counterpart of DNA happens during the synthesis phase, or S stage, of the cell cycle, before the cell joins mitosis or meiosis. The elucidation of the configuration of the dual helix furnished a hint as to how DNA is copied. Recollect that adenine nucleotides band with thymine nucleotides, as well as with cytosine with guanine. This implies that the two strands are complementary to each other. Here, in the given diagram strand, (i) indicates the continuous strand or we can say a leading strand, on the other hand, strand (ii) represents the discontinuous or the lagging strand. In the lagging strand, okazaki fragments are formed which are later on attached together to form a new complementary strand of the template DNA with help of DNA ligase.
So, the right answer to the question is Option – C “Discontinuous replication stands (i)”

Note: In the DNA replication over the two templates dividend in contrary directions. One strand with polarity 3′→5′ forms its corresponding strands continuously due to the 3′end of the latter is clear for elongation. It is known as the leading strand.