Humans And Yeast As A Model For Human Biology Essay

831 Words Nov 2nd, 2015 4 Pages
Humans and the baker’s yeast Saccharomyces cerevisiae diverged from a common ancestor about 1 billion years ago and have shared several thousand orthologous genes, accounting for more than one-third of the yeast genome. The homology between humans and yeast, and the inherent tractability of yeast, had made researchers expand its usefulness as a model for human biology, by both heterologous expression of human proteins, as well as by modifying the yeast cells directly to humanize specific amino acids, proteins or even yeast pathways. To determine whether genes retained ancestral functions over a billion years ago of evolution and to identify principles of deep evolutionary divergence, there had to be replacement of 414 essential yeast genes with their human orthologs, examining the complementation of lethal grown defects upon the yeast genes (1). There are studies that ranged in their degree of direct translation to humans, from using yeast proteins to identify targets for human drugs to large-scale replacement of yeast genes with their human orthologs (2). The yeast humanization can be broken down into five degree types. Degree 0 Studying nonhumanized yeast to address human biology, Degree 1: Expressing human proteins in yeast, regardless of orthology, Degree 2: Humanizing specific positions within native yeast genes, Degree 3: Humanizing entire yeast genes, and Degree 4: Humanization of full pathways and complexes (2). In Degree 0, humanized yeasts are in disease gene…

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