DNA is duplicated during the S phase (Synthesis phase) of the cell cycle.
The cell cycle is a repeating series of growth, DNA replication, and division, resulting in two new cells called "daughter" cells. The S phase is a critical part of this cycle because it ensures that each daughter cell receives a complete and accurate copy of the genetic material.
Here's a breakdown of why the S phase is when DNA replication occurs:
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Purpose of S Phase: The primary purpose of the S phase is to precisely duplicate the entire genome. This involves unwinding the DNA double helix, separating the two strands, and using each strand as a template to synthesize a new complementary strand.
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Mechanism of Replication: Enzymes like DNA polymerase play a crucial role in adding nucleotides to the new strand, following the base-pairing rules (Adenine with Thymine, and Guanine with Cytosine). This results in two identical DNA molecules, each consisting of one original strand and one newly synthesized strand (semi-conservative replication).
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Importance of Accurate Replication: Accurate DNA replication is essential for maintaining the integrity of the genome and preventing mutations that could lead to cell dysfunction or diseases such as cancer. The S phase includes mechanisms to proofread and correct any errors that might occur during replication.
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Timing in the Cell Cycle: The S phase occurs after the G1 (Gap 1) phase, where the cell grows and prepares for DNA replication, and before the G2 (Gap 2) phase, where the cell continues to grow and prepares for cell division (mitosis or meiosis).
In summary, the S phase is specifically dedicated to DNA replication, ensuring that each daughter cell receives a complete and accurate copy of the genetic information necessary for its proper function.
