A portion of a human gene is isolated from the genome and sequenced. The corresponding segment of mRNA is isolated from the cytoplasm of human cells, and it is also sequenced. The nucleic acid strings shown here are from genomic coding strand DNA and the corresponding mRNA.

Does this intron contain normal splice-site sequences?

Verified step by step guidance

1. Step 1: Understand the problem. The question asks whether the intron in the genomic DNA contains normal splice-site sequences. Splice sites are specific sequences at the boundaries of introns and exons that are recognized by the spliceosome during RNA splicing. The canonical splice-site sequences are typically 'GU' at the 5' end of the intron and 'AG' at the 3' end of the intron.
2. Step 2: Identify the intron region in the genomic DNA sequence. Introns are non-coding regions that are removed during RNA splicing. Compare the genomic DNA sequence with the mRNA sequence to locate the intron, as the mRNA sequence will only contain exons (coding regions).
3. Step 3: Examine the 5' and 3' ends of the intron in the genomic DNA sequence. Look for the presence of the canonical splice-site sequences ('GU' at the 5' end and 'AG' at the 3' end). These sequences are critical for proper splicing.
4. Step 4: Analyze the surrounding sequences for additional splice-site consensus motifs. Besides the 'GU' and 'AG' sequences, other conserved regions such as the branch point (usually an 'A' located upstream of the 3' splice site) and polypyrimidine tract (a sequence rich in pyrimidines near the 3' splice site) should also be checked.
5. Step 5: Conclude whether the intron contains normal splice-site sequences based on the analysis. If the canonical 'GU' and 'AG' sequences, along with other conserved motifs, are present, the intron likely contains normal splice-site sequences. If these sequences are absent or mutated, splicing may be impaired.

Key Concepts

Introns and Exons

Introns are non-coding sequences of DNA that are transcribed into pre-mRNA but are removed during RNA splicing. Exons, on the other hand, are the coding sequences that remain in the mature mRNA and are translated into proteins. Understanding the distinction between introns and exons is crucial for analyzing gene structure and function.

Splice Sites

Splice sites are specific nucleotide sequences at the boundaries of introns and exons that signal where splicing should occur. The consensus sequences at these sites, typically found at the 5' and 3' ends of introns, are recognized by the spliceosome, the complex responsible for removing introns from pre-mRNA. Identifying these sequences is essential for determining if an intron contains normal splice-site sequences.

RNA Splicing

RNA splicing is the process by which introns are removed from pre-mRNA and exons are joined together to form mature mRNA. This process is vital for the correct expression of genes, as it ensures that only the coding regions are translated into proteins. Analyzing the splicing process helps in understanding gene regulation and the potential impact of mutations on protein synthesis.