Excision

Definition

Excision is a molecular process in which specific segments of DNA are removed or cut out from a larger sequence. This mechanism is crucial for maintaining genetic integrity and plays a significant role in DNA repair, transposition, and recombination, allowing organisms to adapt by removing harmful or non-functional elements from their genomes.

5 Must Know Facts For Your Next Test

1. Excision can be performed by enzymes known as nucleases, which recognize and cleave specific sequences of DNA.
2. This process is essential for the removal of damaged DNA segments, thereby preventing mutations that could lead to diseases like cancer.
3. In transposition, excision is often a preliminary step where the transposable element is cut out from its original location before being inserted elsewhere.
4. Excision can also play a role in the immune system's ability to diversify antibody genes through a process called somatic recombination.
5. The precise excision of DNA is critical for gene therapy approaches that aim to correct genetic defects by removing faulty genes.

Review Questions

• How does excision contribute to the processes of recombination and transposition?
  • Excision plays a fundamental role in both recombination and transposition by facilitating the removal of specific DNA segments. In recombination, excised pieces can be rearranged and integrated into different locations, enhancing genetic diversity. In transposition, excision allows transposable elements to detach from their original site, enabling them to relocate within the genome and potentially alter gene expression.
• Discuss the significance of excision in maintaining genomic integrity and preventing diseases such as cancer.
  • Excision is vital for maintaining genomic integrity as it allows cells to eliminate damaged or potentially harmful DNA sequences. By cutting out these problematic segments, excision prevents mutations that could lead to uncontrolled cell growth and cancer. This repair mechanism is crucial for cellular health, ensuring that only accurate and functional genetic information is preserved during cell division.
• Evaluate the implications of excision in modern gene therapy approaches aimed at correcting genetic disorders.
  • In modern gene therapy, excision serves as a key technique for correcting genetic disorders by allowing the targeted removal of faulty genes. This precise manipulation can restore normal function to affected genes and improve patient outcomes. However, careful consideration must be given to the potential risks associated with unintended excisions or disruptions in other important genomic regions. Successful application of excision in gene therapy could revolutionize treatment strategies for various hereditary diseases.

Related terms

Recombination: A biological process where genetic material is rearranged to create new combinations, often leading to genetic diversity and evolution.

Transposition: The movement of genetic elements, known as transposons or 'jumping genes,' from one location in the genome to another, which can influence gene expression and genome structure.

DNA Repair: The collection of processes by which a cell identifies and corrects damage to its DNA molecules that encode its genome.