500-1000 nucleotides long. Not all of the pre-mRNA is translated. Ribosomal RNA Up to 3000 nucleotide bases long. Ribosomes are the site of protein synthesis in the cytoplasm. To be translated, the mRNA must be in contact with a ribosome.
Ribosomes have two subunits, one slightly larger than the other.
The mRNA first binds to a site on a small ribosomal subunit. The initiation complex attracts a large subunit, completing the ribosome. The first tRNA floats away and is recycled. The ribosomal subunits separate and are recycled. The polypeptide chain folds into a three-dimensional protein.