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.
Both [a] and [r] are true and [r] is the correct reason for [a]
Evaluating Assertion [a] and Reason [r]
Assertion [a] Validity: Ab Initio Gene Finding Inaccuracy
The assertion states that ab initio gene finding algorithms predicting protein-coding genes in eukaryotic genomes are not completely accurate. This is true. Eukaryotic genomes are complex, featuring introns and exons, alternative splicing, and varying gene structures. Ab initio methods, which rely solely on sequence patterns and statistical models without using known homologous sequences, struggle to perfectly capture these complexities. Factors like short exons, unusual codon usage, and the probabilistic nature of identifying gene features lead to inherent limitations and inaccuracies.
Reason [r] Validity: Splice Site Prediction Difficulty
The reason claims that eukaryotic splice sites are difficult to predict. This is also true. Splice sites mark the boundaries between introns and exons. While there are consensus sequences (like the GT-AG rule), these sequences are often degenerate and can appear elsewhere in the genome. Furthermore, the length and composition of introns and exons can vary significantly. Predicting these sites accurately requires sophisticated models that can balance sequence information with other signals, and errors in splice site prediction are a major source of inaccuracy in gene finding.
Relationship Between Assertion and Reason
The difficulty in predicting eukaryotic splice sites (Reason [r]) is a primary reason for the inaccuracy of ab initio gene finding algorithms (Assertion [a]). These algorithms heavily depend on correctly identifying splice junctions to delineate exons and introns. When splice sites are misidentified, the predicted gene structure will be incorrect, leading to false positives (predicted genes that don't exist) or false negatives (actual genes missed), or incorrect exon/intron boundaries. Therefore, the challenge mentioned in the reason directly explains the limitation stated in the assertion.
Conclusion
Both the assertion and the reason are factually correct. The difficulty in predicting splice sites is a key factor contributing to the imperfect accuracy of ab initio gene finding algorithms in eukaryotes. Thus, the reason correctly explains the assertion.
Correct Option: Both [a] and [r] are true and [r] is the correct reason for [a]
Important Questions from Regulation of Gene Expression
- Which of the following conditions induce(s) the expression of $ \beta$-galactosidase gene in the lac operon?
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.- 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?
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?
