reciprocal meiotic recombination

Definition

Target type: biologicalprocess

The cell cycle process in which double strand breaks are formed and repaired through a single or double Holliday junction intermediate. This results in the equal exchange of genetic material between non-sister chromatids in a pair of homologous chromosomes. These reciprocal recombinant products ensure the proper segregation of homologous chromosomes during meiosis I and create genetic diversity. [PMID:2087779]

Reciprocal meiotic recombination is a crucial process in sexual reproduction, ensuring genetic diversity and proper chromosome segregation during cell division. It involves the exchange of genetic material between homologous chromosomes, leading to the formation of new combinations of alleles. The process can be broken down into several key steps:

1. **Synapsis and Homologous Pairing:** During prophase I of meiosis, homologous chromosomes align themselves precisely side-by-side, a process called synapsis. This pairing is facilitated by proteins that recognize and bind to specific DNA sequences, ensuring that the correct chromosomes pair up.

2. **Double-Strand Break Formation:** Once paired, one of the homologous chromosomes undergoes a double-strand break (DSB) in its DNA. These breaks are introduced by specialized enzymes called topoisomerases.

3. **Strand Invasion and Holliday Junction Formation:** The broken ends of the DNA molecule invade the intact DNA of the homologous chromosome, displacing a strand and forming a structure called a Holliday junction. This junction represents a point of crossover between the two chromosomes.

4. **Branch Migration:** The Holliday junction can move along the DNA molecule, exchanging genetic information between the two chromosomes. This process is facilitated by specialized enzymes that break and rejoin DNA strands.

5. **Resolution:** The Holliday junction is eventually resolved, leading to the separation of the two chromosomes. The resolution can occur in two different ways, resulting in either a crossover or a non-crossover event. In a crossover event, the two chromosomes exchange genetic information, leading to the formation of recombinant chromosomes. In a non-crossover event, the chromosomes retain their original genetic information.

6. **Sister Chromatid Cohesion:** Throughout meiosis, sister chromatids remain attached to each other, ensuring that the correct number of chromosomes is distributed to each daughter cell. This attachment is crucial for maintaining the integrity of the genome during meiotic division.

7. **Meiotic Recombination and Genetic Diversity:** Reciprocal meiotic recombination generates new combinations of alleles on chromosomes, contributing significantly to genetic diversity. This diversity is essential for adaptation to changing environments and for the evolution of new species.

8. **Meiotic Recombination and Chromosome Segregation:** Meiotic recombination also plays a critical role in proper chromosome segregation. The crossovers formed during recombination ensure that homologous chromosomes are correctly aligned and separated during meiosis I, preventing aneuploidy (abnormal chromosome numbers) in gametes.

In summary, reciprocal meiotic recombination is a highly regulated and essential process that involves multiple enzymatic steps, ensuring the accurate exchange of genetic information between homologous chromosomes. This exchange contributes to genetic diversity, promotes proper chromosome segregation, and ultimately contributes to the successful transmission of genetic information from one generation to the next.'
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Proteins (3)

Compounds (25)