Starting translation at the authentic (correct) start codon is essential for translation of the correct polypeptide. Errant translation starting at the wrong codon, or even at the wrong nucleotide of the start codon, may produce an abnormal polypeptide and result in a nonfunctional protein. Compare and contrast the mechanisms used by bacteria and eukaryotes to identify the authentic start codon during translation initiation. a. Base pairing between the 16S rRNA in the 30S ribosome
b. A purine-rich Shine-Dalgarno sequence pairs with a complementary pyrimidine-rich segment containing the sequence UCCUCC
c. The authentic start codon is embedded in a consensus sequence, the Kozak sequence
d. The preinitiation complex recruited to the 5'-cap region of mRNA a short mRNA sequence located a few nucleotides .

1. In bacteria
2. In eukaryotes