Outline the current model for DNA synthesis.

Verified step by step guidance

1. Start by explaining that DNA synthesis, also known as DNA replication, is the process by which a cell duplicates its DNA before cell division, ensuring each daughter cell receives an identical copy.
2. Describe the key enzyme DNA polymerase, which adds nucleotides to the growing DNA strand complementary to the template strand, synthesizing DNA in the 5' to 3' direction.
3. Explain the role of the replication fork, where the double-stranded DNA is unwound by helicase to create two single-stranded templates for replication.
4. Discuss the difference between the leading strand, which is synthesized continuously, and the lagging strand, which is synthesized discontinuously in short fragments called Okazaki fragments.
5. Mention the involvement of other important proteins such as primase (which synthesizes RNA primers to initiate DNA synthesis), ligase (which joins Okazaki fragments), and single-strand binding proteins (which stabilize the unwound DNA).

Key Concepts

DNA Replication Fork

The DNA replication fork is the Y-shaped region where the double helix is unwound to allow synthesis of new strands. It consists of leading and lagging strands, with enzymes working to replicate DNA in opposite directions simultaneously.

Enzymes Involved in DNA Synthesis

Key enzymes include DNA helicase (unwinds the helix), DNA polymerase (adds nucleotides to the new strand), primase (synthesizes RNA primers), and ligase (joins Okazaki fragments). These enzymes coordinate to ensure accurate and efficient DNA replication.

Leading and Lagging Strand Synthesis

DNA synthesis is continuous on the leading strand, moving toward the replication fork, while the lagging strand is synthesized discontinuously in short Okazaki fragments away from the fork. This difference arises due to DNA polymerase’s 5’ to 3’ synthesis direction.