mRNA and tRNA Differences
Date: Spring 2011
Do mRNA strands fold like tRNA strands do, making H bonds? If not, what prevents this from happening?
A single strand of mRNA can indeed base pair with itself. This complementary pairing forms secondary structures called stem or hairpin loops. The loops are the result of unpaired nucleotide sequences. These are critically important in tRNA; they form the anticodon that attaches to the mRNA (and works with the ribosome) to assemble proteins from amino acids.
In mRNA, loop structures can also play a role in transcription termination. The loop causes the mRNA to become disassociated from RNA polymerase, halting transcription.
On a related note, a method known as antisense technology can exploit mRNA's tendency to base pair. This is useful when a gene of interest needs to be "silenced". For example: the original gene of interest is copied and reinserted upside down and backwards. This in turn produces an antagonistic mRNA transcript that binds to the original gene's mRNA transcript. The result is double stranded RNA (dsRNA), which is immediately flagged by the cell as aberrant and targeted for destruction. Thus, the original gene product is throttled back or stopped entirely.
Dr. Tim Durham
Instructor, Office of Curriculum and Instruction
Department of Biological Sciences
Florida Gulf Coast University
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Update: June 2012