How many main steps are there in eukaryotic mRNA processing?

In eukaryotic cells, mRNA processing is a crucial step that ensures the stability and functionality of the mRNA before it is translated into protein. The main steps involved in this process include three critical modifications:

1. 5' Capping: A modified guanine nucleotide is added to the 5' end of the nascent mRNA transcript. This cap protects the mRNA from degradation and is necessary for ribosome binding during translation.

2. Polyadenylation: The addition of a poly(A) tail at the 3' end of the mRNA molecule consists of a series of adenine nucleotides. This modification also aids in protecting the mRNA from degradation, facilitates export from the nucleus, and enhances translation efficiency.

3. Splicing: Introns, which are non-coding sequences within the mRNA, are removed, and exons, the coding sequences, are joined together. This process ensures that the final mRNA contains only the sequences that will be translated into proteins.

These three steps collectively prepare the mRNA for its eventual role in protein synthesis, marking a significant difference between prokaryotic and eukaryotic gene expression, where prokaryotic mRNA does