During the posttranscriptional processing of pre-mRNA, a 5' cap is added to an mRNA. Arrange the following steps of the capping process in the CORRECT order. 1. Addition of a guanine nucleotide via a 5'-5' bond
2) Removal of a phosphate from a ribonucleotide triphosphate at the 5' head of the pre-mRNA
3) Methylation at the 2' position of the sugar in the second and the third nucleotides
4) Methylation at position 7 of the terminal guanine base
A) 1, 2, 3, 4
B) 2, 4, 1, 3
C) 4, 1, 3, 2
D) 2, 1, 4, 3
E) 3, 2, 4, 1

Question

Quizplus · Accepted Answer

The correct order of steps in the capping process is: first, a phosphate is removed from the 5' end of the pre-mRNA (step 2), then a guanine nucleotide is added via a 5'-5' bond (step 1), followed by methylation at position 7 of the guanine base (step 4), and finally, methylation occurs at the 2' position of the sugar in the second and third nucleotides (step 3).

During the Posttranscriptional Processing of Pre-MRNA, a 5' Cap Is