Molecular Genetics of Prokaryotes Problem Set

Problem 12: Features of nuclear RNA processing

Help to answer the question

Which of the following is NOT part of RNA processing in eukaryotes?
A. splicing of exons
B. reverse transcription
C. addition of a 5' cap
D. addition of a poly A tail
E. intron removal


RNA processing
The details of RNA processing in eukaryotes was previously reviewed in the tutorial for Question 1.

The important processing steps are the following:
1. Capping. A modified G-nucleotide, termed a "cap", is added to the 5'-end of most mRNA. The cap is retained in mRNA, and functions in ribosome binding and mRNA stability.
2. 3'-Polyadenylation. A tail of A-nucleotides, generally 100-200 long, is added to the 3'-end of most eukaryotic pre-mRNAs. The poly A tail, which is not coded in the DNA, is also retained in the mRNA exported to the cytoplasm.
3. Intron Splicing and Splicing of Exons. The pre-mRNA transcripts often contain introns, which are noncoding sequences that interrupt the coding regions known as exons. Introns are removed and exons are joined together by the spliceosome in the nucleus.

The Biology Project
University of Arizona
Tuesday, November 4, 1997
Contact the Development Team
All contents copyright © 1997. All rights reserved.