Question

Eukaryotic messenger RNA can undergo post synthetic processing after transcription and before translation. One of the processing steps is splicing, where portions of the RNA are removed and the remaining RNA are joined together. Classify the statements regarding mRNA splicing as true or false.
1. Splicing occurs while the mRNA is attached to the nucleosome

2. One mRNA can sometimes code for more than one protein by splicing at alternative sites.

3. Splicing occurs while the mRNA is still in the nucleus.

4. The spliceosome consists of five small RNA molecules and many associated proteins.

5. Proteins in the spliceosome recognize the 5' and 3' splice site sequences.

5. Proteins in the spliceosome recognize the 5' and 3' splice site sequences.

Answer 1

Answer: 1. False; 2. False; 3. True; 4. True; 5. False;

Explanation: Splicing is a process in which the replicated RNA is "cleared" and becomes RNAm. In it, a specific part known as intron is recognized and removed by a molecule called spliceosome, a large and complex RNA-protein formed of 5 small nuclear ribonucleoproteins and approximately 80 proteins and occurs inside the nucleous. After the splicing the RNAm can procede to produce protein outside the nucleous.

To recognize the introns, the proteins in the spliceosome recognize the 5' end site of the sequence.

This system allows another method: an alternative splicing in which more than  one RNAm can be formed from the same gene, which means a diversity in eukaryptic cells.