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9 Cards in this Set
- Front
- Back
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Linked genes
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Genes that are located on the same chromosome Are close enough that they tend to be inherited together |
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Thomas Morgan Hunt (1909)
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Working with Drosophila, crossed a wild type (dominant) and black fly. Expected a 9:3:3:1 ratio, but got only wild type and black, no mixed. Genes were linked, two dominant phenotypes and two recombinant offspring |
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Recombinant offspring
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Rare cases of crossing over between the linked genes
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How genes are transmitted
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Independent Assortment (Mendel) Linkage without crossing over (completely linked) Linkage with crossing over |
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Transmission shown
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Independent Assortment - 8 spaces Completely Linked - no space Linkage with crossing over - 4 spaces |
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Recombinants
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Crossing over occurs during Meiosis I
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Linkage with crossing over
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The farther apart genes are, the greater the probability that crossing over will occur between them
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Crossing over frequency
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Number of recombinants -------------------------------------- X 100 Total number of offspring |
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Map distance
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One map distance= 1% crossing over frequency
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