Question

Who explained the operon model for the first time?
(a)Francos Jacob
(b)Jacques Monod
(c)Francois Jacob and Jacques Monod
(d)Beadle and Tatum

Answer 1

Hint: The first operon explained was lac operon in E. coli, which encodes a protein necessary for the utilization of lactose sugar. For this discovery of the operon model Nobel prize in physiology or Medicine is shared.

Complete answer:
Lac operon model study is done on Francois Jacob and Jacques Monod together. They found that operon is found only in prokaryotes, which are groups of genes that are transcribed at the same time. They studied this operon mechanism in the Pasture Institute of Paris.

Additional Information: -The lac operon codes for enzymes involved in the catabolism of lactose.
-It is the inducible operon since the presence of lactose induces the operon to switch on.
-The lac operon consists of three genes involved in processing the sugar lactose.
Gene I- lacZ = β-galactosidase
Gene II- lac Y = galactose permease
Gene III- lac A = thio- galactoside transacetylase
-In the absence of lactose as an inducer, the regulator gene produces a repressor protein which binds to the operator site and prevents the transcription as a result, the structural gene does not produce mRNA and the protein is not formed.

So, the correct answer is, ‘ Francois Jacob and Jacques Monod.’

Note: -Lactose is the disaccharide that is made up of glucose and galactose.
-β-galactosidase enzyme hydrolyses lactose into glucose and galactose.
- Galactose permease protein found in the cytoplasmic membrane helps in the transport of lactose into the cell.