Question

When DNA replication starts

• A. The leading strand produces Okazaki fragments.
• B. The hydrogen bonds between the nucleotides of two strands break.
• C. The phosphodiester bonds between the adjacent nucleotides break.
• D. The bonds between the nitrogen base and deoxyribose sugar break.

Answer 1

Answer: (B)

The hydrogen bonds between the nucleotides of two strands break.

DNA replication is the process by which the DNA duplicates itself. At the start of the DNA replication, the hydrogen bonds between the nucleotides of two strands break by the action of enzyme helicase. RNA primer attaches on the template strand which provides a 3' end for DNA polymerase to work on. The DNA is synthesized by DNA polymerase in the 5'-3' direction on leading strand by DNA polymerase. When the DNA polymerase works in the opposite direction on lagging strand it synthesizes discontinuous short DNA segments known as Okazaki in 3'-5' direction. DNA ligase is the enzyme which helps in joining the Okazaki segments and forms the continuous complimentary strand of the daughter DNA.

So, the correct answer is option B.