Determine the correctness or otherwise of the following Assertion [a] and the Reason [r].
Assertion [a]: In multicellular organisms, cells of different lineages have different gene expression profiles.
Reason [r]: Alternative splicing is the only mechanism to generate protein diversity.
Analyzing Assertion [a] Gene Expression & Reason [r] Protein Diversity
This question assesses the understanding of gene expression in multicellular organisms and the mechanisms of protein diversity.
Assertion [a] Analysis: Gene Expression Profiles
Assertion [a] states that in multicellular organisms, cells of different lineages have different gene expression profiles. This is true.
- Multicellular organisms are composed of various specialized cell types (e.g., nerve cells, muscle cells, skin cells).
- Cell differentiation, the process by which cells become specialized, involves the selective activation and silencing of specific genes.
- This differential gene expression results in distinct sets of proteins being produced in each cell type, leading to unique structures and functions, hence different gene expression profiles.
Reason [r] Analysis: Protein Diversity Mechanisms
Reason [r] claims that alternative splicing is the only mechanism to generate protein diversity. This is false.
- Alternative splicing is a significant mechanism that allows a single gene to code for multiple proteins by varying the exons included in the final messenger RNA (mRNA).
- However, it is not the sole mechanism. Protein diversity is also generated through other processes like:
- Post-translational modifications (e.g., phosphorylation, glycosylation).
- Differential gene promoter usage.
- RNA editing.
- Variations in transcription and translation rates.
- Because alternative splicing is not the *only* mechanism, the reason is false.
Conclusion
The Assertion [a] is true, as different cell lineages demonstrably have different gene expression patterns. The Reason [r] is false because alternative splicing, while important, is not the exclusive method for generating protein diversity.
Therefore, the correct option is that [a] is true but [r] is false.
Important Questions from Regulation of Gene Expression
- Which of the following conditions induce(s) the expression of $ \beta$-galactosidase gene in the lac operon?
- The event(s) that lead(s) to inactivation of tumor suppressor genes in cancer cells is(are)
- Which of the following statement(s) is(are) CORRECT regarding the $lac$ operon in $E. coli$ when grown in the presence of glucose and lactose?
Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]
Assertion: Ab initio gene finding algorithms that predict protein coding genes in eukaryotic genomes are not completely accurate.
Reason: Eukaryotic splice sites are difficult to predict.
A recombinant protein is to be expressed under the control of the lac promoter and operator in a strain of E. coli having the genotype $lacI^+ \ crp^+$. Even in the absence of inducer IPTG, low levels of expression of the recombinant protein are seen (leaky expression). Which one of the following should be done to minimize such leaky expression?
