Question

Which three statements correctly describe the process that takes place before a mature mrna exits the nucleus?

Answer 1

The correct answer will be-

1. Poly-A tailing

2. Splicing

3. Capping

Step-by-step explanation:

The mRNA molecule formed in the nucleus through transcription is not protected from the external environment.

The mRNA for translation has to be transported from the nucleus to the cytosol so certain modification takes place in the mRNA.

The three types of modification are:

1. Tailing: The polyadenylation reaction takes place at the 3' end of the pre-mRNA which adds adenyl groups to the end which protects the mRNA.

2. Capping: The capping reaction is performed at the 5' end of the RNA where the modified guanine nucleotides are added.

3. Splicing: The process of removal of the non-coding sequence from the mRNA is known as splicing.

Thus, Poly-A tailing, Splicing and Capping is the correct answer.

Answer 2

After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis in the ribosomes; this may be described by; A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.; A poly-A tail of about 50 to 250 adenine nucleotides is added to the 3' end of the pre-mRNA, and also the Non-coding sequences called introns are spliced out by molecular complexes called spliceosomes.