Final answer:
In mRNA structure, the term UTR stands for Untranslated Region, which includes both the 5' UTR and 3' UTR flanking the protein-coding sequence. These regions are involved in regulating the stability and translation of the mRNA.
Step-by-step explanation:
The term UTR when applied to the structure of mRNA stands for Untranslated Region. This refers to sequences in the mRNA that are not translated into protein. Specifically, these are the regions found at both ends of the mRNA molecule. The 5' UTR is located upstream of the protein-coding region, and the 3' UTR is downstream of the coding region. These UTRs play roles in the regulation of gene expression by influencing mRNA stability and translation efficiency.
Eukaryotic mRNA typically contains additional features such as a 5' cap, which is a methylated guanosine triphosphate (GTP) molecule that attaches to the 5' end of the mRNA and protects it from degradation. Furthermore, the presence of RNA-binding proteins at the 5' or 3' UTR can significantly affect the stability of the RNA molecule, which in turn controls the availability of the mRNA for translation.