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🔬general biology i review

Helicases

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Helicases are specialized enzymes that unwind and separate the two strands of DNA during processes such as replication and repair. This unwinding is crucial because it creates the single-stranded DNA templates needed for synthesis of new strands or for the repair mechanisms to function effectively.

5 Must Know Facts For Your Next Test

  1. Helicases play a vital role in DNA replication by unwinding the double helix so that DNA polymerase can synthesize new strands.
  2. These enzymes utilize energy derived from ATP hydrolysis to facilitate the unwinding process, making them essential for both replication and repair.
  3. In addition to replication, helicases are involved in several DNA repair pathways, ensuring that damaged or improperly paired bases can be corrected.
  4. There are various types of helicases, each with specific functions and preferences for particular substrates within the cell.
  5. Defects in helicase function can lead to genomic instability and are associated with certain diseases, including some cancers and genetic disorders.

Review Questions

  • How do helicases contribute to the process of DNA replication?
    • Helicases contribute to DNA replication by unwinding the double-stranded DNA at the replication fork, creating two single-stranded templates that DNA polymerase can use to synthesize new complementary strands. Without helicases, the double helix structure would remain intact, preventing access to the genetic information required for copying. Their action is essential for establishing the environment necessary for accurate and efficient DNA synthesis.
  • Discuss the role of helicases in DNA repair mechanisms and why their activity is critical for maintaining genomic integrity.
    • Helicases play a crucial role in various DNA repair mechanisms by unwinding damaged regions of DNA, which allows repair proteins access to these sites. For example, during nucleotide excision repair, helicases help remove sections of damaged DNA by first unwinding the surrounding area. This activity ensures that any mutations or errors can be corrected, maintaining the overall integrity of the genome and preventing potential diseases resulting from uncorrected damage.
  • Evaluate the consequences of helicase malfunction on cellular function and its potential link to diseases.
    • Malfunctioning helicases can lead to significant consequences for cellular function, as they disrupt normal processes like DNA replication and repair. This disruption may result in increased rates of mutation, chromosomal instability, and failure to properly manage DNA damage. The link between helicase defects and diseases is highlighted by certain conditions such as cancer and genetic disorders like Bloom syndrome, where genomic instability due to helicase deficiencies leads to heightened susceptibility to malignancies and other health issues.