What is the basis for the difference in the synthesis of the leading and lagging strands of DNA molecules? The anti-parallel arrangement of the DNA strands. The RNA primers are required to initiate DNA elongation. DNA polymerase joins new nucleotides to the 3' end of the growing strand. Helicase and single-stranded binding proteins work at the 5' end of the DNA strand.
Correct answer: B. I and III
- A. I and IV
- B. I and III
- C. II and IV
- D. II and III
Explanation
The DNA strands are antiparallel i.e. run in opposite directions. Synthesis of new daughter strand by DNA polymerase is only in the 5' to 3' direction, thus the DNA template is read in the 3' 5' direction. This means only the leading strand can be synthesized continuously because the DNA polymerase is moving in the same direction as the unwinding DNA. The lagging strand is synthesized discontinuously, because the DNA polymerase has to move away from the unwinding enzyme in the 5' to 3' direction.
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