Question

Give two examples about inducible/repressible gene expression. Explain the function of the genes, the mechanism of the regulation, and why it is important to have a way to control the level of gene expression.

Answer 1

Give two examples about inducible/repressible gene expression.

Example: inducible:1)lactose 2)lac

  repressible:1)Trp 2)trp

Explain the function of the genes, the mechanism of the regulation

Function

Genes decide almost everything about a living being. One or more genes can affect a specific trait. Genes may interact with an individual’s environment too and change what the gene makes.

Genes affect hundreds of internal and external factors, such as whether a person will get a particular color of eyes or what diseases they may develop.

Some diseases, such as sickle-cell anemia and Huntington’s disease, are inherited, and these are also affected by genes.

mechanism of the regulation:

Regulation of gene expression, or gene regulation,[1] includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA). Sophisticated programs of gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources. Virtually any step of gene expression can be modulated, from transcriptional initiation, to RNA processing, and to the post-translational modification of a protein. Often, one gene regulator controls another, and so on, in a gene regulatory network.

Master operon: In S. typhimurium and related species, there is a regulatory hierarchy that governs the transcription of the flagellar genes of 3 classes.The master operon (flhDC) is a sole operon in class 1 and is transcribed by the “housekeeping” sigma factor 70 (σ70).2,323 The sequences upstream of the flhDC operon are fairly diverse among bacterial species. In E. coli, the flhDC expression is affected by several genes and physiological factors: the heat shock proteins (DnaK, DnaJ, and GrpE), the pleiotropic response regulator (OmpR) activated by acetyl phosphate, and the DNA-binding protein H-NS. More such genes and factors have been discovered in other species.

and why it is important to have a way to control the level of gene expression.:

The translation of mRNA can also be controlled by a number of mechanisms, mostly at the level of initiation. Recruitment of the small ribosomal subunit can indeed be modulated by mRNA secondary structure, antisense RNA binding, or protein binding. In both prokaryotes and eukaryotes, a large number of RNA binding proteins exist, which often are directed to their target sequence by the secondary structure of the transcript, which may change depending on certain conditions, such as temperature or presence of a ligand (aptamer). Some transcripts act as ribozymes and self-regulate their expression

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