BIOL 201 Lecture Notes - Lecture 8: Precursor Mrna, Alternative Splicing, Prokaryotic Translation

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 201
• Professor: Gary Brouhard

Document Summary

The brief existence of an mrna molecule begins with transcription, and ultimately ends in degradation. During its life, an mrna molecule may also be processed, edited, and transported prior to translation. Eukaryotic mrna molecules often require extensive processing and transport, while prokaryotic molecules do not. Transcription is when rna is made from dna. During transcription, rna polymerase makes a copy of a gene from the dna to mrna as needed. This process is similar in eukaryotes and prokaryotes. One notable difference, however, is that prokaryotic rna polymerase associates with mrna-processing enzymes during transcription so that processing can proceed quickly after the start of transcription. The short-lived, unprocessed or partially processed product is termed precursor mrna, or pre-mrna; once completely processed, it is termed mature mrna. Processing of mrna differs greatly among eukaryotes, bacteria, and archea. Non-eukaryotic mrna is, in essence, mature upon transcription and requires no processing, except in rare cases.