HMB265H1 Chapter Notes - Chapter 20: Pleiotropy, Rhodopsin, Ommatidium
13 Dec 2019
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H4 histone protein conserved over roughly 2 billion years. Development of insect eyes and vertebrate eyes evolved from a single prototypical light-sensing organ. Evolution is not only conservative, it is innovative; two species may evolve the same trait independently. Mutagenesis screens one of the first steps in determining which genes are required for a certain process. Drosophila compound eye screens done easily by looking at the eyes under a microscope. Mechanism of development assembly of 8 photoreceptors, the last of which being r7 (contains rhodopsin; enables flies to detect uv light) Upon screening for mutants and complementation test revealed that two genes, sevenless (sev) and bride-of-sevenless (boss), were involved in the loss-of-function mutation in r7. Can use deletion mapping & p-element tagging with inverse pcr. Whole-genome sequencing becoming more popular as it becomes cheaper to do. Both sev and boss have hydrophobic domains suggests they can traverse through the cell membrane and be found on the surface of particular cells.
