Name: Incomplete Linkage in Drosophila
Uploaded: 2019-07-19
Duration: 8 min 39 s
Description: Completely linked genes show zero recombination. What about incomplete linkage? How can we predict the exact number of recombinants in a progeny? Learn about...

Question

Give an account of linkage and recombination.

Accepted Answer

Morgan through his crossing experiments observed that two genes did not follow Mendel’s law of independent assortment. The likelihood of achieving a parental combination if two genes are situated closely at the nearby locus on the same chromosome was relatively higher in the subsequent generation in comparison to the non-parental combination. The physical connection between such closely placed genes was referred to as linkage.

Genes are said to be linked when genes for different traits are located in similar chromosomes and hence are bonded to each other. It is a deviation from the Mendelian principle of independent assortment that is appropriate to be applied to the genes that are situated on different chromosomes. Linkage was discovered by the British geneticist William Bateson, Edith Rebecca Saunders and Reginald Punnett.

The term genetic recombination described the non-parental gene combinations in a dihybrid cross.

Recombination is a process of producing new combinations of alleles by the recombination of DNA molecules. In this phenomenon, there is an exchange of genetic material between two different chromosomes or between different regions of the same chromosome. This process is observed in both eukaryotes and prokaryotes. It increases the genetic diversity or variations of sexually reproducing organisms.

The different types of Recombination are as follows:

Homologous Recombination- This type of recombination occurs between chromosomes of similar sequences and is carried out during meiosis.

Non-homologous recombination: This type of recombination occurs between chromosomes of dissimilar sequences.

Site-specific Recombination- This is observed between very short sequences that usually contain similarities.

Mitotic Recombination- This type occurs during interphase.

Give an account of linkage and recombination.

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