Question

The lac operon is regulated via positive and negative regulation. Explain how each
mechanism works on this operon, and under which circumstances will the operon be
turned on. Include the definition of an operon
2. What are the advantages to a microbe of having inducible enzymes? What is the
function of toluene in the experiment where you induced enzyme function?

Answer 1

Ans1-)Operon is defined as the group of genes generally the structural genes are present on the chromosome and thus these structural genes are transcribed together.
Operon generally consist of regulator, operator and structural genes.
1. Absence of Lactose:
When the Inducer which is Lactose is absent, then the repressor gene will produce the repressor protein which is active and thus bind to the operator region. And thereby preventing the RNA polymerase to transcribe the genes and no protein is being formed.

2. Presence of Lactose:
When the inducer which is a Lactose is present, will fit and will inactivate the repressor protein. Thus, the repressor protein cannot bind to the operator. Hence, the RNA polymerase can now sit on the operator region and will bind to the promoter region and will transcribe the genes.
Gene Z encodes for Beta- Galactosidase
Gene Y encodes for Permease
Gene A encodes for Transacetylase.
Operon is turned on when the Inducer(Lactose) is present.

Ans 2-) Advantages of microbe
1. Energy is saved as when there is no use of the enzyme it will not make it.
2. Also, cost of resource is very less. The expression of inducible enzyme occurs only under the condition which require it.

Toluene will decrease the cell viability. Also, turbidity will be reduced.