Final answer:
In eukaryotic cells, the initiator tRNA (Met-tRNAi^Met) binds to the P site of the small 40S ribosomal subunit during translation initiation.
Step-by-step explanation:
The initiator tRNA (Met-tRNAi^Met) binds to the P site of the small 40S ribosome in eukaryotes. During the initiation of translation, the small ribosomal subunit first binds to the mRNA and then scans it until it encounters the start codon AUG. At this point, the initiator tRNA, carrying methionine (Met), binds directly to the P site of the ribosome, forming an initiation complex with other initiation factors and a ready 'A site' for the next aminoacyl-tRNA.
This binding event is crucial as it sets the reading frame for the mRNA being translated and determines where the polypeptide synthesis will begin. In eukaryotes, unlike in prokaryotes, the methionine attached to the initiator tRNA is not formylated, making eukaryotic initiator tRNAs unique. After the formation of the initiation complex, the large ribosomal subunit joins, and translation proceeds with the elongation phase where successive tRNAs bind to the A site.