Question

Prokaryotic ribosomes are the 70S. Here’s S refer to
(a)Svedberg unit
(b)Smallest unit
(c)Smooth
(d)Speed

Answer 1

It is used as a non-Système Internationale unit for sedimentation rate and represented as S and the sedimentation rate is a measure by observing under the induced gravitational field of a centrifuge how quickly particle sediment from a solution or suspension.

Complete answer:
In the ribosome the Svedberg unit(S), which is the measurement of the rate of sedimentation in centrifugation rather than size in the ribosome. In the ribosome, the 70S ribosomes (50S and 30S subunits) in the prokaryotic where the small subunit has a 16S RNA subunit consisting of 1540 nucleotides, bound to 21 proteins, and the large subunit is composed of a 5S RNA subunit, a 23S RNA subunit, and 31 proteins.
The ratio of the speed of a substance to its acceleration in comparable units in a centrifugal field is called the sedimentation coefficient. For example a substance with a sedimentation coefficient of 1S (${ 10 }^{ -13 }{ s }$) will travel at 1 mm per second (${ 10 }^{ -6 }{ m }{ s }^{ -1 }$) under the influence of acceleration of ${ 10 }^{ 6 }$ G (${ 10 }^{ 7 }{ m }{ s }^{ -2 }$) and centrifugal acceleration is given as ${ r }{ \omega }^{ 2 }$ where r is the radial distance from the rotation axis and ${ \omega }$ is the angular velocity in radians ${ s }^{ -1 }$.

Additional information:

1. The name of the Svedberg unit given after Theodor Svedberg{ Swedish chemist (1884–1971)}. This chemist also won the Nobel Prize in chemistry for his work on colloids and the invention of the ultracentrifuge in 1926.
2. The Svedberg coefficient is a nonlinear function. The value of ‘S’ is determined by a particle's mass, density, and shape and it depends on the frictional forces retarding its movement, which, in turn, are related to the average cross-sectional area of the particle.
3. It has been observed that bigger particles tend to sediment faster and so have higher Svedberg values and Svedberg units are not directly additive since they represent a rate of sedimentation, not weight.

Note: In the process of ultracentrifugation yields, the 70S ribosome as well as the separated ribosomal subunits, the large subunit (50S), and the small subunit (30S) are produced in bacterial ribosomes. Ribosomes normally exist as a mixture of joined and separate subunits within a cell. It has been observed that near the bottom of the tube the whole ribosomes sediment but in upper fractions, the smaller particles (separate 50S and 30S subunits) can be found.