A mutation in which of the following sequence in eukaryotic mRNA will affect the process by which poly-A tail is added to 3’end of mRNA ?
**Core Concept**
In eukaryotic cells, the process of adding a poly-A tail to the 3' end of mRNA is a crucial step in mRNA maturation. This process is mediated by the enzyme poly-A polymerase, which adds adenine nucleotides to the 3' end of the mRNA. The addition of the poly-A tail is initiated by a specific sequence of nucleotides known as the poly-A signal or poly-A addition site.
**Why the Correct Answer is Right**
The correct answer involves the recognition of the poly-A signal sequence by the poly-A polymerase enzyme. The poly-A signal sequence is a specific sequence of nucleotides (AAUAAA) that is recognized by the poly-A polymerase enzyme. This recognition event triggers the addition of adenine nucleotides to the 3' end of the mRNA, resulting in the formation of a poly-A tail. The poly-A tail plays a crucial role in mRNA stability and translation efficiency.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option does not specify a sequence that is involved in the recognition of the poly-A signal by the poly-A polymerase enzyme.
* **Option B:** This option is not a recognized sequence involved in the process of poly-A tail addition.
* **Option C:** This option may be a sequence involved in other aspects of mRNA processing, but it is not directly involved in the recognition of the poly-A signal.
**Clinical Pearl / High-Yield Fact**
The poly-A tail is a critical factor in mRNA stability and translation efficiency. Mutations in the poly-A signal sequence can lead to aberrant mRNA processing and have significant implications for gene expression.
**Correct Answer: A. AAUAAA**