The ribosome is the crucial cellular organelle where protein synthesis occurs.
They read the sequence of messenger RNA (mRNA) and conduct translation to produce amino acid strings which then form proteins.
Ribosomes are not membrane-bound and float freely in the cytoplasm.
These organelles do not require a membrane to carry out their functions and thus are devoid of it.
A membrane around the ribosome would mean that the transport of proteins into the ribosome would be energy-consuming. Thus, the lack of a membrane enables the easy exchange of amino acids.
The lack of a membrane enables them to recruit translational RNA (tRNA) released by the nucleus in order to conduct translation.