Question

Three covalent modifications can be made to an RNA molecule in eukaryotic cells before the RNA molecule becomes a mature mRNA. Which of the following is not one of

these modifications?
A) A poly-A tail is added.
B) A 5' cap is added.
C) Introns can be spliced out.
D) Phosphorylation
E) All of the above

Answer 1

D) Phosphorylation is not one of the three covalent modifications that can be made to an RNA molecule. The three modifications are adding a poly-A tail, adding a 5' cap, and splicing out introns.

Step-by-step explanation:

The correct answer is D) Phosphorylation. Phosphorylation is not one of the three covalent modifications that can be made to an RNA molecule in eukaryotic cells before it becomes a mature mRNA. The three modifications are:

1. Adding a poly-A tail to the 3' end of the RNA molecule. This tail consists of a string of adenine nucleotides and helps protect the mRNA from degradation and facilitate its export from the nucleus.
2. Adding a 5' cap to the 5' end of the RNA molecule. This cap is made up of a modified guanosine nucleotide and plays a role in initiating translation by ribosomes.
3. Splicing out introns from the RNA molecule. Introns are non-coding regions that are removed from the primary transcript to generate a mature mRNA consisting of coding regions called exons.