How 50s+ 40s = 70s??
Dear student,
Ribosomes are generally identified and denoted by the sedimentation coefficient (S). Sedimentation coefficient is the ratio of the velocity to the acceleration applied to the centrifuge at which the ribosomes will sediment. So, by 70 S we mean the sedimentation coefficient of whole ribosomes is 70; but if we break up the ribosomes into units then one of the subunit sediments at a coefficient of 50S while other at 30S.
So 50s+30s makes 70s.
Hope this information helps.
Regards.