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Pleiotropy - cellular-molecular evolution in action

Published on October 31, 2016   16 min

A selection of talks on Genetics & Epigenetics

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0:00
Pleiotropy: Cellular-Molecular Evolution in Action. My name is John Torday. This lecture is one in the series of lectures on evolutionary physiology.
0:11
Pleiotropy occurs when one gene is used for several seemingly unrelated purposes, not unlike manipulating a Rubik's cube with a gear pictured on one of its faces, showing up on other faces of the cube as shown here.
0:27
Yet we know that all the genes of the organism are present in the zygote and are distributed throughout during embryogenesis. So there are underlined principles that may account for the pleiotropisms. Shown here are the origins for the first principles of evolution, which could hypothetically dictate where in house such pleiotropy genes would be located.
0:51
Such evolved pleiotropic traits had their mechanistic origins in such first principles and then progressed to form the various complex traits of physiology with reference to those principles as evolution.
1:05
At the molecular level, the functional evolution of such traits can be traced in a way that cholesterol has been exploited by eukaryotes. Starting with its synthesis in response to the rising levels of oxygen in the atmosphere shown in A, generating cholesterol by a biogenetic pathway require 11 molecules of oxygen for 1 molecule of cholesterol shown in B. The integration of cholesterol into the cell membranes of eukaryotes facilitated evolution due to the thinning of the cell membrane. Increasing oxygenation, metabolism, and locomotion, the three principles of vertebrate evolution. Subsequently, cholesterol evolved to form lipid rafts in the cell membrane as the infrastructure of cell surface receptors which ultimately evolved the endocrine system. Cholesterol being the substrate for the steroid hormones and vitamin D.

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