As mentioned previously, eukaryotic translation is very similar overall to prokaryotic translation. There are a few notable differences, however. These include the follwing:

• Eukaryotic mRNAs do not contain a Shine-Delgarno sequence. Instead, ribosomal subunits recognize and bind to the 5' cap of eukaryotic mRNAs. In other words, the 5' cap takes the place of the Shine-Delgarno sequence.
• Eukaryotes do not use formyl methionine as the first amino acid in every polypeptide; ordinary methionine is used. Eukaryotes do have a specific initiator tRNA, however.
• Eukaryotic translation involves many more protein factors than prokaryotic translation (For example, eukaryotic initiation involves at least 10 factors, instead of the 3 in prokaryotes.)

Translation: Summary of Key Points

• Translation is the synthesis of a polypeptide using the information encoded in an mRNA molecule. The process involves mRNA, tRNA, and ribosomes. Ribosomes are large organelles made of two subunits, each of which is composed of ribosomal RNA and proteins.
• tRNA has a unique structure that exposes an anticodon, which binds to codons in an mRNA, and an opposite end that binds to a specific amino acid. Binding of an amino acid to a tRNA is carried out by an enzyme called aminoacyl tRNA synthetase in a process called charging.
• Translation consists of three basic steps: initiation, elongation, and termination. Initiation involves the formation of the ribosome/mRNA/initiator tRNA complex. Elongation is the actual synthesis of the polypeptide chain, by formation of peptide bonds between amino acids. Termination dissociates the translation complex and releases the finished polypeptide chain. Each of these steps requires the activity of a specific set of protein factors in addition to the ribosome, tRNA, and mRNA.
• Ribosomes serve as sites that encourage tRNA binding to the appropriate codon. The tRNA molecules are shuttles, bringing the correct amino acids into position so they can be connected to each other by peptidyl transferase.