In the galactose operon of E. coli, a repressor, encoded by the galR gene, binds to an operator site,galo, to regulate the expression of three structuralgenes, galE, galT, and galK. Expression is inducedby the presence of galactose in the media. For eachof the strains listed, would the cell show constitutive, inducible, or no expression of each of the structural genes? (Assume that galR− is a loss-of-functionmutation.)a. galR−galo+galE+galT+galK+b. galR+galocgalE+galT+galK+ c. galR−galo+galE+galT+galK−/galR+galo+galE−galT+galK+d. galR−galocgalE+galT+galK−/galR+galo+galE−galT+galK+
Gene Interactions
When the expression of a single trait is influenced by two or more different non-allelic genes, it is termed as genetic interaction. According to Mendel's law of inheritance, each gene functions in its own way and does not depend on the function of another gene, i.e., a single gene controls each of seven characteristics considered, but the complex contribution of many different genes determine many traits of an organism.
Gene Expression
Gene expression is a process by which the instructions present in deoxyribonucleic acid (DNA) are converted into useful molecules such as proteins, and functional messenger ribonucleic (mRNA) molecules in the case of non-protein-coding genes.
In the galactose operon of E. coli, a repressor, encoded by the galR gene, binds to an operator site,
galo, to regulate the expression of three structural
genes, galE, galT, and galK. Expression is induced
by the presence of galactose in the media. For each
of the strains listed, would the cell show constitutive, inducible, or no expression of each of the structural genes? (Assume that galR− is a loss-of-function
mutation.)
a. galR−galo+galE+galT+galK+
b. galR+galoc
galE+galT+galK+ c. galR−galo+galE+galT+galK−/
galR+galo+galE−galT+galK+
d. galR−galoc
galE+galT+galK−/
galR+galo+galE−galT+galK+
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