After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template fo
r protein synthesis on the ribosomes. Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
1. Poly-A Tailing at 3'end: The 3'end terminus is polyadenlated in the nucleoplasm. This poly-A tail may be from 20-250 nucleotide long. This tail protects mRNA from attack by 3'exonuclease.
2. Capping at 5' end: Eukaryotic mRNAs are all capped at the 5' terminus by 7-methyl guanosine triphosphate. This occur in the nucleus.
3. Removal of Introns: the primary transcript contains coding region (exons) and non coding region (Introns). They intron are cleaved and exons are spliced. This is also done in the nucleus.
An astronaut who weighed 150 pounds on Earth found that his weight on Jupiter was 400 pounds. He captured an alien that weighed 120 pounds on Jupiter. What is the alien's weight on Earth?