Recombination
Recombination is the primary mechanism that brings about variation in populations. It is a process of the exchange of genetic material between double or single-stranded DNA and RNA, to obtain offspring with a new combination of alleles. It is a natural process.
It is commonly seen in eukaryotes during gamete formation. While undergoing meiosis, the chromosomes in the gametes crossover to pass on a novel set of genetic sequences to the offspring.
It is also seen in prokaryotes such as bacteria and archaea during mitosis in asexual reproduction.
Genetic recombination is of four types:
- Homologous Recombination
- Non-homologous Recombination
- Site-specific Recombination
- Replicative Recombination
The study of recombination allows in understanding the genetic mechanisms, identifying linkage groups, mapping chromosomes and certain gene anomalies.
However, experimental or artificial recombination can be lethal to human health and the environment, and also raises ethical questions.
Homologous Recombination
Homologous recombination is a type of genetic recombination in which the exchange of genetic material takes place between identical strands of DNA and RNA, both double or single-stranded.
It is useful in bringing genetic diversity and also helps in DNA repair.
Refer: Homologous Recombination in Eukaryotes, Bacteria and Viruses
Site-specific Recombination
Site-specific recombination, also known as conservative site-specific recombination, is the exchange of genetic material between two DNA strands that possess a certain level of sequence homology. Sequence homology in nucleic acids and proteins is defined in terms of shared ancestry in their evolution.
Mechanism
Site-specific recombinases (SSRs) are enzymes that bind to the short DNA sequences, cleave DNA backbones, and aid in the exchange of DNA helices. Finally, it rejoins the strands. In some cases, accessory proteins and accessory sites are also required.
Site-specific recombination is a fast, specific and efficient method. It is seen in bacterial genome replication, pathogenesis and differentiation, and movement of mobile genetic elements.
Homologous vs Site-specific Recombination
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Homologous Recombination |
Site-specific Recombination |
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Definition | |
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Homologous recombination is the mechanism of the exchange of genetic material between two identical DNA or RNA strands. |
Site-specific recombination is the exchange of genetic material between DNA strands that possess a certain level of sequence homology. |
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Length of the strand | |
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The exchange occurs between long DNA strands. |
The exchange occurs between short DNA strands, between 30-200 nucleotides in length. |
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Location | |
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It occurs anywhere in the homology. |
It occurs only at specific sites. |
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Enzymes Required | |
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The enzyme machinery is relatively simple and small for homologous recombination. |
It requires specific enzymes and enzyme machinery for recombination. |
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Examples | |
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Explore BYJU’S Biology to learn more about recombination and related topics.
Also Read:
- Why Genetic Recombination Is So Important?
- What Is the Difference Between Recombination and Mutation?
- Bacterial Genetics – Conjugation, Transduction, Transformation
Frequently Asked Questions on Difference between Homologous Recombination and Site-Specific Recombination
What is the difference between homologous and nonhomologous recombination?
Homologous recombination is the exchange of genetic material between identical strands, whereas non-homologous recombination is the addition of new genetic material to the chromosomes, also known as lateral gene transfer.
What is the difference between homologous and heterologous chromosomes?
Homologous chromosomes have alleles located on the same loci, whereas heterologous chromosomes have their alleles on different genes.
What is the purpose of homologous recombination?
Homologous recombination is important for DNA repair, preventing damage to replication forks, and overall chromosomal maintenance.
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