SYNTENY MAPPING - SYNTENY MAPPING In the last lecture we...

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SYNTENY MAPPING In the last lecture we saw that genes that are close together on the samechromosome will not show independent assortment during meiosis. Wealso saw that we can take advantage of the fact that crossing-over orrecombination will still allow all possible combinations of alleles to beformed to"map" the genes. However, mapping genes does not tell uswhich chromosome they are on, it only identifies which genes are on thesame chromosome ( linkage group ). Before 1968, of the 700 human genes that had been defined only the 10%that showed a sex-linked pattrern of inheritance could be associated witha specific chromosome -the X in this case. Several key discoveries made before 1969 along with another in that yeardramatically improved our ability to associate linkage groups with specificchromosomes in humans. Since the set of genes on a specificchromosome are said to be syntenic, the process was referred to assynteny mapping. Prior key discoveries included: 1) Chromosome Identity. Until chromosome banding procedures weredeveloped, the best that could be done with certainty in humanswas to group chromosomes into classes based on overall size andthe relative lengths of each of the arms. Thus, chromosomes were classed into groups A-G. Group C included 7 chromosomes (thosenow identified as # 6 to #12). 2) Isozymes. Isozymes are copies of an enzyme that differ slightly inamino acid sequence. They are often detected by electrophoresisof proteins in a gel followed by detection of the position ofprotein based on stains that are deposited as a consequence of
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This note was uploaded on 04/29/2008 for the course GENE 310 taught by Professor Magill during the Spring '08 term at Texas A&M.

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SYNTENY MAPPING - SYNTENY MAPPING In the last lecture we...

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