Question

The extent of complementarity of a miRNA with its target mRNA determines ___________________________.

1) whether the mRNA will be degraded or transported elsewhere in the cell
2) whether the mRNA will be transported to the nucleus
3) whether RISC is degraded
4) whether the miRNA synthesizes a complementary strand

Answer 1

The degree of complementarity between a miRNA and its target mRNA dictates whether the mRNA will be degraded or translationally repressed by the miRNA-RISC complex.

Step-by-step explanation:

The extent of complementarity of a miRNA with its target mRNA determines whether the mRNA will be degraded or its translation repressed. MicroRNAs (miRNAs) are key post-transcriptional regulators that control the stability and translational efficiency of target mRNAs.

mRNAs with strong complementarity to the miRNA-RISC (RNA-induced silencing complex) are degraded. This is because miRNAs guide RISC to bind to target mRNAs and can either inhibit their translation or promote their degradation, depending on the degree of complementarity. If an miRNA is fully complementary to the target mRNA, the mRNA is more likely to be cleaved and degraded. In the case of partial complementarity, translation repression is more often observed.

MiRNAs initially are transcribed as pre-miRNAs, which fold into a stem-loop structure and are processed into mature forms. These mature miRNAs are then incorporated into the RISC, guiding the complex to target specific mRNAs based on sequence complementarity. This regulatory process plays a crucial role in ensuring correct gene expression and function in the cell, allowing miRNAs to bind and affect the mRNA's fate, resulting in either degradation or translational repression.