Jacob and Monod proposed operon concept on the basis of their study of lactose metabolism in Escherichia coli. The concept is applicable toa)All prokaryotes onlyb)All prokaryotes and some qukaryotesc)All prokaryotes and all eukaryotesd)All prokaryotes and some protozoanasCorrect answer is 'C'. Can you explain this answer?

Question

Answer

The answer is C. Operon model was given by Jacob and Monod (1961) for regulation of protein synthesis in prokaryotes. In bacteria, the genes that contain the information for assembling the enzymes for a metabolic pathway are usually clustered together on the chromosome in a functional complex called an operon.Regulation of protein synthesis in eukaryotes is explained by gene battery model given by Britten and Davidson. The model assumes the presence of four classes of sequences – (a) producer gene which is comparable to structural gene of prokaryotic operon, (b) receptor site which is comparable to operator gene, (c) integrator gene which is comparable to regulator gene and (d) sensor site which regulates the activity of integrator gene.

Answer

Correct answer is option b

Answer

Understanding the Operon Concept
The operon concept, proposed by Jacob and Monod, is a fundamental principle in molecular biology that explains gene regulation in prokaryotes. This concept primarily emerged from their studies on the lactose (lac) operon in Escherichia coli, illustrating how genes can be co-regulated.
Applicability of the Operon Concept
The operon model is primarily applicable to:

All Prokaryotes: The operon structure is a hallmark of prokaryotic gene organization. In bacteria, genes that encode proteins with related functions are often grouped together under a single promoter, allowing for coordinated expression.
Some Eukaryotes: While the operon concept is not as prevalent in eukaryotes, certain eukaryotic organisms, such as some protozoa and fungi, exhibit operon-like structures. These structures can allow for the simultaneous expression of functionally related genes, but they are less common and more complex than in prokaryotes.

Why Not All Eukaryotes?
In contrast to prokaryotes, eukaryotic gene expression is typically more intricate, involving multiple regulatory elements, enhancers, and introns. Eukaryotic genes are primarily expressed individually rather than in clusters, which makes the traditional operon model less applicable to the vast majority of eukaryotic organisms.
Conclusion
Thus, the correct interpretation of the operon concept is that it primarily applies to all prokaryotes and some eukaryotes. The distinction is crucial for understanding genetic regulation across different domains of life.

Answer

The answer is C. Operon model was given by Jacob and Monod (1961) for regulation of protein synthesis in prokaryotes. In bacteria, the genes that contain the information for assembling the enzymes for a metabolic pathway are usually clustered together on the chromosome in a functional complex called an operon.Regulation of protein synthesis in eukaryotes is explained by gene battery model given by Britten and Davidson. The model assumes the presence of four classes of sequences – (a) producer gene which is comparable to structural gene of prokaryotic operon, (b) receptor site which is comparable to operator gene, (c) integrator gene which is comparable to regulator gene and (d) sensor site which regulates the activity of integrator gene.

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