Operon concept B Sc III Dr Narayan Mane
Operon concept B. Sc. III Dr. Narayan Mane Department of Zoology GKG College Kolhapur
Introduction • Gene- A unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring. • Basic unit of hereditary. • Gene carries the heridiatory characters of living characters. • Expression of gene is responsible for the development of particular character. • These expression depends upon various factors and express according to requirements.
• Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. • These products are often proteins, but in non-protein coding genes such as transfer RNA (t. RNA) or small nuclear RNA (sn. RNA) genes, the product is a functional RNA. • The process of gene expression is used by all known life— eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea), and utilized by viruses—to generate the macromolecular machinery for life. • Several steps in the gene expression process may be modulated, including the transcription, RNA splicing, translation, and post-translational modification of a protein. • Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. • Gene regulation may also serve as a substrate for evolutionary change, since control of the timing, location, and amount of gene expression can have a profound effect on the functions (actions) of the gene in a cell or in a multicellular organism.
• In genetics, gene expression is the most fundamental level at which the genotype gives rise to the phenotype, i. e. observable trait. • The genetic code stored in DNA is "interpreted" by gene expression, and the properties of the expression give rise to the organism's phenotype. • Such phenotypes are often expressed by the synthesis of proteins that control the organism's shape, or that act as enzymes catalysing specific metabolic pathways characterising the organism. • Regulation of gene expression is thus critical to an organism's development.
• The first control system for enzyme production worked out at the molecular level described the control of enzymes that are produced in response to the presence of the sugar lactose in E. coli cell. • The work was performed by Jacob and Monod for which they were awarded the Nobel Prize. • The following is the pathway that leads to the production of glucose and galactose.
Several proteins involved in lactose metabolism in the E. coli cell. They are: • ß-galactosidase - converts lactose into glucose and galactose • ß-galactoside permease - transports lactose into the cell • ß-galactoside transacetylase - function unknown • All of the genes involved in controlling this pathway are located next to each other on the E. coli chromosome. Together they form an operon.
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