Inheritance160-page7

Inheritance160-page7 - This was just the first time someone...

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Inheritance Patterns - 7 This knowledge adds some interesting complications to the predicted patterns of inheritance and also explains why recombination, which we discussed with meiosis, is so important as a source of variation. In 1908, researchers discovered a dihybrid cross in sweet peas that did not give the predicted Mendelian ratio of 9:3:3:1. They could not explain why their results were closer to 75% and 25% (the 3:1 ratio expected for a monohybrid cross). Ultimately it was shown that the flower color and pollen length (the genes observed) were on the same chromosome. Since we inherit entire chromosomes rather than independent genes, all genes on one chromosome are inherited together as a single unit (called the linkage group), and we should expect a 3:1 inheritance ratio for the linkage group.
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Unformatted text preview: This was just the first time someone had seen this. Inheritance of two linked genes in pea plant The Effect of Recombination on Gene Linkage and Inheritance Researchers did numerous crosses of traits to identify gene linkage, and carefully noted percentages and ratios. However, some of the time, the results did show independent assortment of the "linked" genes, not enough to indicate the genes were indeed on separate chromosomes, but frequently enough to search for explanations. It was known that a phenomenon called crossing over occurred during meiosis. The effect of crossing over on sister chromatids provided an explanation for the "recombined" allele forms in gene linkage experiments....
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This note was uploaded on 12/29/2011 for the course BIO 151 taught by Professor Edwards during the Spring '10 term at SUNY Stony Brook.

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