Understanding Step 2 of DNA Replication: Elongation and Synthesis of New DNA Strands

Step 2 of DNA replication

Step 2 of DNA replication is the elongation or synthesis of new strands of DNA

Step 2 of DNA replication is the elongation or synthesis of new strands of DNA. This process occurs when the DNA strands separate and serve as templates for the assembly of new complementary DNA strands. The elongation of the new strands is carried out by an enzyme called DNA polymerase.

To begin elongation, an enzyme called primase synthesizes a short RNA primer on each DNA strand. This primer provides a starting point for DNA polymerase to attach and begin synthesizing new DNA.

Once the primers are in place, DNA polymerase attaches to the primer and starts adding nucleotides to the growing DNA strand. It moves along the DNA template strand in the 3′ to 5′ direction, synthesizing the new DNA strand in the 5′ to 3′ direction. The DNA polymerase reads the template strand and adds complementary nucleotides based on the base-pairing rules (A with T and G with C).

As DNA polymerase adds nucleotides to the growing strand, it continuously proofreads the chain for mistakes. If an incorrect nucleotide is added, the DNA polymerase is able to detect the error and remove the nucleotide. The correct nucleotide is then added in its place. This proofreading ability ensures the accuracy of DNA replication.

DNA polymerase continues to move along the template strand, adding nucleotides and elongating the new DNA strands. The two DNA strands are synthesized simultaneously but in opposite directions due to the antiparallel nature of the DNA molecule. As a result, one new DNA strand is synthesized continuously in a smooth process called the leading strand synthesis, while the other new DNA strand is synthesized discontinuously in short fragments called Okazaki fragments. These fragments are later connected by another enzyme called DNA ligase.

Overall, in step 2 of DNA replication, DNA polymerase elongates the new strands of DNA by adding complementary nucleotides to the primers. This process ensures the accurate replication of the DNA molecule, allowing for the transmission of genetic information to offspring cells.

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