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Questions and Answers
What is the outcome of general recombination between two homologous DNA molecules?
What is the outcome of general recombination between two homologous DNA molecules?
Where can the site of exchange occur in general recombination?
Where can the site of exchange occur in general recombination?
What is formed at the site of exchange in general recombination?
What is formed at the site of exchange in general recombination?
What is required for the formation of a long heteroduplex joint?
What is required for the formation of a long heteroduplex joint?
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What is the mechanism of general recombination based on?
What is the mechanism of general recombination based on?
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What is the result of general recombination in terms of DNA sequence?
What is the result of general recombination in terms of DNA sequence?
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How precise is the cleavage and rejoining of DNA molecules in general recombination?
How precise is the cleavage and rejoining of DNA molecules in general recombination?
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What is necessary for the recognition of homologous regions in general recombination?
What is necessary for the recognition of homologous regions in general recombination?
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What is the primary outcome of DNA rearrangements?
What is the primary outcome of DNA rearrangements?
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What is the term for genetic exchange between a pair of homologous DNA sequences?
What is the term for genetic exchange between a pair of homologous DNA sequences?
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What is the primary function of general recombination in proliferating cells?
What is the primary function of general recombination in proliferating cells?
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What is the result of crossing-over during meiosis?
What is the result of crossing-over during meiosis?
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Why is general recombination essential for accurate chromosome segregation during meiosis?
Why is general recombination essential for accurate chromosome segregation during meiosis?
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What is the evolutionary benefit of general recombination?
What is the evolutionary benefit of general recombination?
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In which type of organisms is general recombination widespread?
In which type of organisms is general recombination widespread?
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What is the relationship between DNA replication and general recombination?
What is the relationship between DNA replication and general recombination?
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Study Notes
DNA Recombination
- DNA rearrangements, caused by genetic recombination, create genetic variation by altering the combination of genes and their expression levels.
- Genetic recombination consists of two broad classes: general recombination and site-specific recombination.
General Recombination
- General recombination (also known as homologous recombination) occurs between a pair of homologous DNA sequences, usually on two copies of the same chromosome.
- This process is essential for every proliferating cell, as it repairs DNA replication accidents and ensures accurate chromosome segregation during meiosis.
- General recombination involves the crossing-over of chromosomes, resulting in the exchange of genetic information and the creation of new combinations of DNA sequences.
- This type of gene mixing is beneficial for evolution and is not confined to multicellular organisms, but is also widespread in single-celled organisms.
Characteristics of General Recombination
- Two homologous DNA molecules "cross over" by breaking and rejoining their double helices to form two intact double helices, each composed of parts of the two initial DNA molecules.
- The site of exchange can occur anywhere in the homologous nucleotide sequences of the two participating DNA molecules.
- At the site of exchange, a strand of one DNA molecule becomes base-paired to a strand of the second DNA molecule, creating a heteroduplex joint.
- The heteroduplex region can be thousands of base pairs long, and no nucleotide sequences are altered at the site of exchange.
- Despite its precision, general recombination creates DNA molecules of novel sequence, tolerating a small number of mismatched base pairs.
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Description
Learn about DNA rearrangements and genetic recombination, including general recombination and site-specific recombination, and their impact on genetic variation.