The role of ribosomes in cells is to synthesize proteins by translating messenger RNA (mRNA) into amino acid sequences. Ribosomes can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum. They play a crucial part in the central dogma of molecular biology, where genetic information is expressed as proteins. By facilitating the assembly of amino acids, ribosomes contribute to the functioning and maintenance of the cell, influencing cellular structure and energy production.