Question

After initial processing in the cytoplasm, miRNAs are imported into the nucleus where they bind to pre-mRNAs.

Options:

OPTION 1: True
OPTION 2: False

Answer 1

The statement is False. MicroRNAs (miRNAs) are initially processed in the nucleus and then function in the cytoplasm by binding to mRNAs, not pre-mRNAs, through RISC complexes to regulate protein synthesis.

Step-by-step explanation:

The statement 'After initial processing in the cytoplasm, miRNAs are imported into the nucleus where they bind to pre-mRNAs' is False.

RNA transcription and the initial processing of miRNAs occur in the nucleus. The mature miRNAs are then exported to the cytoplasm, where they perform their functions.

In the cytoplasm, miRNAs may bind to the 3' UTR of target mRNAs through the RNA-induced silencing complex (RISC), leading to mRNA breakdown or repression of translation, rather than binding to pre-mRNAs in the nucleus.

RNA stability in the cytoplasm is influenced by miRNAs and RNA-binding proteins, which may bind to RNA sequences to modulate the stability and translation of the RNA, subsequently affecting the protein synthesis.