Gene Expression & Environmental Regulation — NEET Biology
📚 Practice ConceptThe genes in a cell are expressed to perform a particular function or a set of functions. For example, if an enzyme called beta-galactosidase is synthesised by E. coli, it is used to catalyse the hydrolysis of a disaccharide, lactose into galactose and glucose; the bacteria use them as a source of energy. Hence, if the bacteria do not have lactose around them to be utilised for energy source, they would no longer require the synthesis of the enzyme beta-galactosidase. Therefore, in simple terms, it is the metabolic, physiological or environmental conditions that regulate the expression of genes. The development and differentiation of embryo into adult organisms are also a result of the coordinated regulation of expression of several sets of genes.
Match the following enzymes with their functions: Column I – Enzyme A. DNA ligase B. RNA polymerase I C. β-galactosidase D. Reverse transcriptase Column II – Function I. Joins Okazaki fragments II. Synthesizes rRNA (28S, 18S, 5.8S) III. Hydrolyzes lactose into glucose and galactose IV. Synthesizes DNA from RNA template
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