An example nutrition of single cells like yeast and

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An example: nutrition of single cells like yeast and bacteria. Yeast cells express preferences about which sugar to use. Interestingly, the proteins used to digest the less preferable sugars are only synthesized when those sugars are present and the more preferable sugars are absent. (Spiegelman et al., PNAS, 1944)
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The Development of the Operon Concept: What Cells The Development of the Operon Concept: What Cells Eat and When They Die Eat and When They Die (Berman et al .) Studies of the cultures of bacterial cells sufficed to lead Jacob and Monod to formulate the operon concept - the revolutionary view that there are certain genes whose mission is to control other genes. This superseded the dictum of Beadle and Tatum which was ``one gene, one enzyme’’. The Mendelian revolution taken to the next stage. Bacterial growth curves (J. Monod)
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Not All DNA Codes for Proteins Not All DNA Codes for Proteins (Berman et al .) The regulatory landscape The E. coli genome is a circle with roughly 4.7 million base pairs. How many genes? An estimate. The genes related to sugar usage have been one of the most important stories in the history of modern biology and biochemistry (and take us right back to the great debate on vitalism played out with Pasteur in the 1800s). “Promoter” region on DNA is subject to intervention by various molecular bouncers that govern the gene.
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Repressors: The Cartoon Repressors: The Cartoon Repressor molecules inhibit action of RNA polymerase. Repressors can be under the control of other molecules (i.e. inducers) that dictate when repressor is bound and not.
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Activators: The Cartoon Activators: The Cartoon Activator molecules enhance the action of RNA polymerase. Activators can be under the control of other molecules (i.e. inducers) that dictate when activator is bound and not. Activators “RECRUIT” the polymerase. Adhesive interaction between RNAP and activator
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The Single Molecule Census The Single Molecule Census (Beautiful work of David Goodsell)
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Ways to Measure Gene Ways to Measure Gene Expression Expression Basic point: looking for “reporters” of the level of expression of gene of interest. Can ask the system to report on the level of gene expression at various steps in the processes linking DNA to active protein. Promoter occupancy, level of mRNA, level of active protein. This image shows a Drosophila embryo colored to show the expression patterns of early gene regulators. Each color represents the level of expression of one of three gene regulators, Knirps (green), Kruppel (blue), and Giant (red). Color intensity reflects a higher level of expression. The darker areas of the embryo are cells where none of these gene regulators are expressed, and the yellowish areas indicate that both Knirps and Giant are being expressed.
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  • Fall '19
  • DNA, Berman

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