![]() ![]() The process of copying shifts to the other parental strand. Therefore, it has only historical importance.Īccording to this theory a portion of one parental strand of homologous chromosome acts as template for the synthesis of a copy of its DNA molecule. However, it has been questioned by several workers. In, 1931, Belling proposed this theory for recombination of chromosome in higher animals. Thus the recombinants contain and ab + and a + b +. Segment b is replaced by a newly synthesized segment copied from b + and attached to a section. One helix of paired homologous chromosome (ab and a + b +) breaks between a and b (Fig. This concept has been used to explain genetic recombination. This type of recombination does not require the synthesis of new DNA. The broken segments rejoin crosswise and yield recombinants containing a and b + segment, and a + and b segment. Two homologous duplex of chromosome laying in paired form breaks between the gene loci a and b, and a + and b + (Fig. Mechanism of Recombination :īasically, there are three theories viz., breakage and reunion, breakage and copying and complete copy choice that explain the mechanism of recombination (Fig.8.23). The work on bacterial genetics was done between 19 that advanced the understanding of microbial genetics at molecular level. Much work was done on eukaryotic genetics until 1945 that laid the foundation of classical genetics. It is made possible through chromosomal exchange resulting from crossing over between the two homologous chromosomes containing identical gene sequences. ![]() Most of the eukaryotes show a complete sexual life cycle including meiosis, an important event that generates new allelic combinations by recombination. The new recombinants show changes in phenotypic characters. ![]() Thus, recombination is the process of formation of new recombinant chromosome by combining the genetic material from two organisms. ![]()
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