DNA replication

Definition

DNA replication is the biological process by which a cell duplicates its DNA, creating two identical copies of its genetic material before cell division. This process is crucial for ensuring that each new cell receives an exact copy of the DNA, which is essential for the continuity of genetic information across generations of cells.

5 Must Know Facts For Your Next Test

1. DNA replication occurs during the S phase of the cell cycle, just before a cell divides.
2. The process begins at specific locations on the DNA molecule called origins of replication, where the double helix unwinds.
3. DNA replication is highly accurate, with proofreading mechanisms in place to correct errors made during synthesis.
4. The leading strand is synthesized continuously, while the lagging strand is synthesized in short segments known as Okazaki fragments.
5. After replication, each daughter cell receives one parental strand and one newly synthesized strand, maintaining genetic consistency.

Review Questions

• Explain how semiconservative replication ensures genetic fidelity during DNA replication.
  • Semiconservative replication ensures genetic fidelity by producing two identical DNA molecules, each containing one original strand and one newly synthesized strand. This method allows the genetic information to be preserved while also providing a template for constructing the new complementary strand. As a result, any errors or mutations that may occur during synthesis are less likely to affect the overall genetic stability, as each new DNA molecule retains a portion of the original template.
• Discuss the roles of key enzymes such as DNA polymerase and ligase in the DNA replication process.
  • DNA polymerase is essential for synthesizing new DNA strands by adding nucleotides to a growing chain based on the template strand. It also has proofreading capabilities to correct mistakes made during replication. Meanwhile, DNA ligase plays a crucial role in joining Okazaki fragments on the lagging strand, sealing gaps between newly synthesized segments to create a continuous DNA molecule. Together, these enzymes ensure that DNA replication is efficient and accurate.
• Evaluate how errors during DNA replication can impact cell function and lead to disease.
  • Errors during DNA replication can result in mutations, which may alter gene function and lead to cellular dysfunction or disease. If these mutations occur in critical genes involved in regulating cell growth or repair mechanisms, they can contribute to cancer development or hereditary disorders. Additionally, if errors go uncorrected due to failures in proofreading mechanisms, they can be passed on to subsequent generations of cells, further compounding potential health issues. Therefore, maintaining accuracy during DNA replication is vital for organismal health and stability.

Related terms

Semiconservative replication: A method of DNA replication where each of the two resulting DNA molecules contains one original strand and one newly synthesized strand.

DNA polymerase: An enzyme that synthesizes new DNA strands by adding nucleotides to a growing chain during replication.

Okazaki fragments: Short segments of DNA synthesized on the lagging strand during DNA replication, which are later joined together by DNA ligase.