Question

After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes.

Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus.

A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
A translation stop codon is added at the 3' end of the pre-mRNA.
Coding sequences called exons are spliced out by ribosomes.
A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.
Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.

Answer 1

Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.

A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.

A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.

Step-by-step explanation: