Create a flow chart of the steps of RNA interference (RNAi). Include the roles of Dicer, Argonaute, and RISC.

The RNAi process involves the recognition of dsRNA, cleavage by Dicer into siRNA or miRNA, incorporation into RISC with Argonaute proteins, and targeting of complementary mRNA for degradation or repression, leading to gene silencing.

Explanation:

Recognition of double-stranded RNA (dsRNA) (either from viruses or other sources) within the cell.
The enzyme Dicer cleaves the dsRNA into small fragments that are about 21-23 nucleotides long, called small interfering RNAs (siRNAs) or microRNAs (miRNAs).
These fragments have two unpaired nucleotides at the 3' end and a 5' phosphate group.
siRNAs or miRNAs are incorporated into the RNA-induced silencing complex (RISC), assisted by Argonaute proteins.
The complex separates the two strands of the siRNA or miRNA and retains the guide strand.
The guide strand within RISC then directs the complex to bind to a complementary target mRNA sequence.
Binding occurs; if the match is perfect for siRNA, the target mRNA is cleaved and destroyed. If it is mostly complementary as in miRNA, translation is inhibited, though cleavage can occur if the match is fully complementary.
Ultimately, the target mRNA is either degraded or its translation is repressed, leading to gene silencing.

This pathway is essential for regulating gene expression and serves as a defense mechanism against viruses and other genetic elements.