Question

In ribosomes, letter “S” signifies
A. Sedimentation coefficient
B. Svedberg's constant
C. Both A and B
D. None of these.

Answer 1

A ribosome is considered as a complex molecular machine that is found inside the living cells which produces proteins from amino acids during the process called translation. This process of synthesizing proteins is the primary function of all living cells. These are specialized organelle which is found in both eukaryotes and prokaryotes. All living cells require ribosomes for the production of proteins.

Complete answer:

The ribosome is a complex of RNA and proteins and therefore called ribonucleoproteins. It is made up of larger and smaller subunits. The smaller subunit is the place where the mRNA gets bounded and in the larger subunit, the amino acids get added. The subunits contain both ribonucleic
Acid and the protein components.
The two subunits are joined together by the interaction of the rRNA of one subunit and protein in the other subunit. Ribosomes are embedded in the cytosol of plant and animal cells.
The ribosome structure includes many components- They are located in two areas of the cytoplasm and they are scattered. Prokaryotes have 70s ribosomes whereas in eukaryotes it is 80s ribosomes. 62 percent of the ribosome is made up of RNA and the rest is the proteins.
Sedimentation coefficient: It is the characteristic of any particle which is subjected to centrifugation. It can be defined as the particle sedimentation ratio velocity to the acceleration applied to cause the sedimentation. Sedimentation speed is also the terminal velocity.
Svedberg constant: It is used to estimate the molecular weight of the protein in the centrifugal movement. The Svedberg unit is S and is often used as the sedimentation rate of the macromolecules.

Hence, the correct answer is option B, Svedberg’s constant.

Note: In the prokaryotic ribosome, they include three rRNA individually and contain the large ribosomal submit which is the 80s. In the eukaryotic cell, the ribosomes have four individual rRNA molecules and have a small ribosomal subunit which is the 70s.