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Multiple Choice
Mature mRNA from a eukaryote would contain each of these features except which of the following?
A
Introns
B
5' cap
C
Poly-A tail
D
Exons
Verified step by step guidance
1
Understand the structure of mature mRNA in eukaryotes: Mature mRNA is processed from precursor mRNA (pre-mRNA) and contains specific features that are essential for its stability and function.
Identify the features of mature mRNA: Mature mRNA typically includes a 5' cap, a poly-A tail, and exons. These features are crucial for mRNA stability, export from the nucleus, and translation.
Clarify the role of each feature: The 5' cap is a modified guanine nucleotide that protects the mRNA from degradation and assists in ribosome binding. The poly-A tail, a stretch of adenine nucleotides, also protects the mRNA and aids in its export and translation. Exons are the coding sequences that are expressed in the protein.
Understand the role of introns: Introns are non-coding sequences that are present in the pre-mRNA but are removed during RNA splicing to form mature mRNA. Therefore, mature mRNA does not contain introns.
Conclude which feature is not present in mature mRNA: Since introns are removed during the processing of pre-mRNA, they are not present in mature mRNA. Thus, the correct answer is 'Introns'.