Tag: inherited changes

The gene that codes for any RNA/protein product which does not serve as regulatory protein is known as structural genes. The operator is a DNA sequence present between the promoter region and the first coding gene. The operator region serves as the repressor protein binding site. The promoter is a DNA segment that serves to initiate transcription of a particular gene. They are present upstream near the transcription start sites of genes in between the operator and structural gene. The regulatory gene regulates the expression of structural genes by its protein products that are mostly transcription factors. It is not the part of an operon, which means that it is present upstream or downstream the structural genes but not in between; the Regulatory gene is present upstream the operator gene. Thus, the correct answer option D.

The regulator gene (or regulatory gene) is the part of the operon system that codes for the repressor protein.

In the operon model, the operator is the gene segment to which a repressor binds. This prevents the RNA polymerase from transcribing certain genes in the operon unit.

Lac repressor is part of the regulatory network of the lac operon. Lac repressor controls the production of three proteins produced from the gene and affecting the metabolism of lactose. This repressor molecule is a tetramer whose all the subunits are identical. This tetramer binds to a particular region in the bacterial DNA called the operator. This region is present next the three lactose metabolizing proteins. Binding of the repressor to operator causes the block in the production of protein. Otherwise, for three genes to transcribe the repressor protein binds to the lactose molecule and hence unable to bind to operator allows the genes to transcribe.

When E. coli is moved from glucose to a lactose-containing medium, the lac operon is induced to produce enzymes necessary for lactose metabolism.

In a repressible operon, the corepressor binds to the inactive aporepressor to form an active repressor complex that can bind to the operator.

In the lac operon, the active repressor protein binds to the operator site, physically blocking RNA polymerase from transcribing the structural genes.

An operon system typically includes the regulator gene, promoter, operator, and the structural genes it controls.

Telomeres, the ends of eukaryotic chromosomes, consist of repetitive DNA sequences that are typically rich in guanine.

The lac operon is a classic example of an inducible operon, meaning it is typically turned off but can be activated (induced) by the presence of lactose. Repressible operons, by contrast, are typically on and turned off by the presence of a product.