25 nm small large ribosome subunit subunit Figure 6-18 The ribosome.A three-dimensional model of the bacterial ribosome as viewed from two angles.The positions of many ribosomal proteins in this structure have been determined by using an electron microscope to visualize the positions where specific antibodies bind,as well as by measuring the neutron scattering from ribosomes containing one or more deuterated proteins.(After J.A.Lake,Annu.Rev.Biochem.54:507- 530,1985.1985 by Annual Reviews Inc.)