Question: where are the majority of ribosomes found inside the cell

title: Ribosome
text: Ribosomes are the workplaces of protein biosynthesis , the process of translating mRNA into protein . The mRNA comprises a series of codons that dictate to the ribosome the sequence of the amino acids needed to make the protein . Using the mRNA as a template , the ribosome traverses each codon ( 3 nucleotides ) of the mRNA , pairing it with the appropriate amino acid provided by an aminoacyl - tRNA . Aminoacyl - tRNA contains a complementary anticodon on one end and the appropriate amino acid on the other . For fast and accurate recognition of the appropriate tRNA , the ribosome utilizes large conformational changes ( conformational proofreading ) . The small ribosomal subunit , typically bound to an aminoacyl - tRNA containing the amino acid methionine , binds to an AUG codon on the mRNA and recruits the large ribosomal subunit . The ribosome contains three RNA binding sites , designated A , P and E. The A-site binds an aminoacyl - tRNA ; the P - site binds a peptidyl - tRNA ( a tRNA bound to the peptide being synthesized ) ; and the E-site ( exit ) binds a free tRNA before it exits the ribosome . Protein synthesis begins at a start codon AUG near the 5 ' end of the mRNA . mRNA binds to the P site of the ribosome first . The ribosome is able to identify the start codon by use of the Shine - Dalgarno sequence of the mRNA in prokaryotes and Kozak box in eukaryotes .