Non-Mendelian Genetics (Odd ball circumstances that Mendel’s work did not account for)

Youtube link for Non-Mendelian Genetic Topics http://www.youtube.com/watch?v=rIe7mPXkYhs&feature=youtu.be As you are viewing this, reference the slides in this powerpoint to help you break down this information OR you may want to print these slides so you can follow along with the video.

Contributions to Non-Menelian Genetics Thomas Hunt Morgan Contributions to Non-Menelian Genetics Included: Gene Linkage Sex-linkage

Gene Linkage

Thomas Hunt Morgan – Fruit flies Gene linkage – the closer genes are in location to one another on the SAME chromosome, the greater the possibility of recombination of the parent’s PHENOtypes (traits recombining & crossing over) of offspring. Anytime the outcomes of offspring in a Punnet square probability result are less than 50% = it verifies that those genes that are located on the SAME chromosome! Vestigial wings - - the term vestigial in this case means = wings that aren't formed enough to allow for true flight (these flies can jump from place to place)

Vestigial wings – Drosophila fly On the left is a picture of a fruit fly with very small wings. This trait arose through a mutation in the vestigial gene, which codes for wing type. The fly on the left carries two copies of the mutant form of this gene. The fly shown on the right is the wild type. It carries two normal (the “wild” types) copies of this gene.

Multiple Genes

Multiple Genes Multiple genes = more than 2 genes are responsible for determining traits such as hitchhikers thumb or height. They become a variation within a range of extreme differences ie: There are probably 6-7 genes that actually determine your height. It is not as cut and dry as saying “tall” or “short.”

Multiple Alleles vs Polygenic Traits The difference between multiple alleles and polygenic traits is …. Multiple alleles (height, blood type) refers to different versions of one gene…. And Polygenic traits refers to a single trait which is controlled by multiple genes (each with multiple alleles) ie: Skin color

Sex-linkage

Sex Linkage Sex linkage = some traits on genes that are only found on the sex genes ie: Hemophilia (Inability for blood to clot), Colorblindness Trait is carried on the “X” chromosome Females can be carriers of trait for colorblindness, however, it is very uncommon for females to inherit the trait for colorblindness Males have a higher propensity to inherit colorblindness because they inherit the X chromosome with the mutation for colorblindness: Xc

Punnet Square for Colorblindness Because the NORMAL X chromosome dominates the trait for vision that detects color, (meaning it does NOT carry the trait for colorblindness) there is only a 25% chance for colorblindness to surface in an individual IF the mother is a carrier for colorblindness. Xc X X Y Xc X X X Xc Y X Y