Portions of eukaryotic mRNA sequence that are removed during RNA processing are ________. a. exons b. caps c. poly-A tails d. introns

Eukaryotic mRNA (messenger RNA) is an RNA molecule that carries the genetic information needed to synthesize a protein. It starts as a pre-mRNA molecule that undergoes various processing events before becoming mature mRNA.

Exons: These are the coding regions of eukaryotic genes, which contain the information for producing proteins. They are joined together during RNA processing. Introns: These are the non-coding regions of eukaryotic genes. They interrupt the coding sequences (exons) and need to be removed during RNA processing to create a continuous coding sequence for translation. Caps: The cap (5' cap) is added to the 5' end of the mRNA molecule during RNA processing. It protects the mRNA molecule from degradation and helps in transport and translation. Poly-A tails: The poly-A tail (3' poly-A tail) is added to the 3' end of the mRNA molecule during RNA processing. It provides stability and enhances translation efficiency.

According to the information explained in Step 2, introns are the non-coding regions that need to be removed during RNA processing to generate mature mRNA with a continuous coding sequence. Therefore, the correct answer is: Portions of eukaryotic mRNA sequence that are removed during RNA processing are (d) introns.