Homologous recombination

Definition

Homologous recombination is a biological process where genetic information is exchanged between two similar or identical strands of DNA, usually occurring during meiosis and DNA repair. This mechanism helps ensure genetic diversity and maintains chromosome integrity by allowing for the accurate repair of double-strand breaks in DNA.

5 Must Know Facts For Your Next Test

1. Homologous recombination plays a crucial role during meiosis, allowing for genetic variation by shuffling alleles between homologous chromosomes.
2. This process is essential for repairing double-strand breaks, which can result from environmental factors or normal cellular processes.
3. In bacteria, homologous recombination is often mediated by proteins like RecA, which help align and exchange strands of DNA.
4. The exchange of genetic material via homologous recombination contributes to evolution by introducing new gene combinations into populations.
5. Errors during homologous recombination can lead to genomic instability and contribute to diseases such as cancer.

Review Questions

• How does homologous recombination contribute to genetic diversity during meiosis?
  • Homologous recombination contributes to genetic diversity during meiosis by allowing homologous chromosomes to exchange segments of their DNA. This process, known as crossing over, results in new combinations of alleles on each chromosome, increasing the variation in the gametes produced. As a result, when fertilization occurs, the offspring have a unique mix of traits inherited from both parents.
• Discuss the role of RecA protein in bacterial homologous recombination and its significance in DNA repair mechanisms.
  • RecA protein plays a vital role in bacterial homologous recombination by facilitating the alignment of homologous DNA sequences and promoting strand exchange. This protein binds to single-stranded DNA, helping to search for and pair with complementary regions on homologous double-stranded DNA. The significance of RecA extends beyond recombination; it is also crucial for the repair of damaged DNA, ensuring that bacterial cells can maintain their genetic integrity in response to environmental stressors.
• Evaluate the impact of errors in homologous recombination on genomic stability and their potential link to cancer development.
  • Errors in homologous recombination can severely impact genomic stability by resulting in improper repair of double-strand breaks or incorrect exchanges of genetic material. Such mistakes can lead to chromosomal rearrangements, duplications, or deletions, which may contribute to the development of cancer. Moreover, the failure of this repair pathway often triggers alternative mechanisms that may be less accurate, further exacerbating genomic instability and increasing the likelihood of tumorigenesis.

Related terms

Crossing Over: A process during meiosis where homologous chromosomes exchange segments of genetic material, leading to genetic variation in the resulting gametes.

RecA Protein: A protein essential for homologous recombination in bacteria that facilitates the pairing and strand exchange between homologous DNA sequences.

Double-Strand Break Repair: A critical DNA repair process that fixes double-strand breaks using homologous recombination or non-homologous end joining to prevent genomic instability.