Genetics II - Genetics.Yet Again.(Ch. 15) 3/25/2008 8:01:00...

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Genetics…Yet Again…(Ch. 15) 25/03/2008 08:01:00 Fig 15.2 Crossing yellow round seeds with green wrinkled We have independent assortment occurring which determines how the  chromosomes are paired during meiosis I. We have to have more genes than chromosomes People hypothesized about inheritance Thomas Hunt Morgan worked with a creature called Drosophila melanogaster He had a bunch that had red eyes which are considered the wild type as that is the  naturally occurring characteristic A fly came out of nowhere and landed on his feeding trays.  This fly had white eyes. DM has four pairs of chromosomes three autosomes and one sex chromosomes so  they are easy to work with. The white eyed fly happened to be a male which he crossed with a red eye female  and all the offspring were red eyed.  The white eye characteristic is recessive. He crossed two of the F1 generation and got 2459 red eyed females, 1011 red eyed  males, and 752 white eyed males.  No white eyed females. So he crossed an F2 white eyed male with an F1 red eyed female He got some white eyed females this time.  This works because this gene is carried  on the X chromosomes.  Females have two X chromosomes while the males only  have one.  So if the females get one red then they will be red even if they have white  gene.  The male will be whatever his X is.  This is called a sex linked trait since it is  found on the sex chromosome. Fig 15.4 If something is on the Y chromosome it is called holandric.
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This note was uploaded on 04/17/2008 for the course BY 123 taught by Professor Cusic during the Spring '07 term at University of Alabama at Birmingham.

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Genetics II - Genetics.Yet Again.(Ch. 15) 3/25/2008 8:01:00...

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