An important organelle found in eukaryotic cells produces ribosomal subunits from proteins and ribosomal rna, also known as rrna. it then sends the subunits out to the rest of the cell where they combine into complete ribosomes. ribosomes make proteins; therefore, this organelle plays a vital role in making proteins in the cell. what is this organelle? a) centriole b) lysosome c) mitochondria d) nucleolus