Outline the current model for DNA synthesis.

Verified step by step guidance

1. Understand that DNA synthesis, also known as DNA replication, is the process by which a cell duplicates its DNA before cell division.
2. Recognize that DNA synthesis occurs in the S phase of the cell cycle and involves the unwinding of the double helix by the enzyme helicase.
3. Identify that DNA polymerase is the key enzyme that adds nucleotides to the growing DNA strand, using the original strand as a template.
4. Note that DNA synthesis is semi-conservative, meaning each new DNA molecule consists of one original strand and one newly synthesized strand.
5. Acknowledge that synthesis occurs in the 5' to 3' direction, with the leading strand synthesized continuously and the lagging strand synthesized in Okazaki fragments.

Key Concepts

DNA Replication

DNA replication is the biological process by which a cell duplicates its DNA, ensuring that each daughter cell receives an identical copy of the genetic material. This process involves unwinding the double helix structure of DNA, followed by the synthesis of new complementary strands using existing strands as templates. Key enzymes, such as DNA polymerase, play crucial roles in adding nucleotides and proofreading the newly synthesized DNA.

Leading and Lagging Strands

During DNA synthesis, the two strands of the DNA helix are replicated differently. The leading strand is synthesized continuously in the direction of the replication fork, while the lagging strand is synthesized in short segments called Okazaki fragments, which are later joined together. This difference arises because DNA polymerase can only add nucleotides in a 5' to 3' direction, necessitating a more complex approach for the lagging strand.

Role of Enzymes in DNA Synthesis

Various enzymes are essential for the DNA synthesis process. Helicase unwinds the DNA double helix, while primase synthesizes short RNA primers that provide a starting point for DNA polymerase. Additionally, ligase is responsible for sealing gaps between Okazaki fragments on the lagging strand, ensuring the integrity of the newly synthesized DNA. These enzymes work in a coordinated manner to facilitate accurate and efficient DNA replication.