Ribosomes are about 15nm by 20nm insize and are made of 2 sub units 50s and 30s units which when present together form 70s prokaryotic ribosomes. How do they form 70s ribosomes? Explain ?
Answer
There are two types of Ribosomes
Prokaryotic Ribosome - 70s
Eukaryotic Ribosome - 80s
Both the Ribosomes 70s and 80s are composed of 2 subunits.
70s is formed of two subunits 50s and 30s.
and
80s is formed of two subunits 60s and 40s.
where, 's' stands for Sedimentation Coefficient.
's' i.e. Svedberg's unit which is a measure of density and size.
50s + 30s is not equal to 80s. Instead, it is 50s + 30s is equal to 70s.
In a Centrifuge Machine, as per the density the samples sediments in the corresponding zones. Thus, the larger sub-unit shows 50s sedimentation while smaller shows 30s sedimentation.
The sedimentation of entire Ribosome is not the sum of 50s and 30s but less due to unavailability of two open surfaces.
Hence, 50s and 30s = 70s.
The two sub-units combine during the protein synthesis process for translation of mRNA into Proteins.
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