Question

The largest subunit of prokaryotic ribosomes is
A. 30S
B. 40S
C. 50S
D. 60S

Answer 1

Hint: The largest subunit of ribosome catalyzes the formation of the peptide bond, provides a site for proteins that initiate initiation, elongation, and termination, and helps in folding of protein after synthesis. The eukaryotic ribosome is 80S type, which is made up of 60S and 40S.

Complete answer:
The word “prokaryote” is derived from Greek words pro means before and karyon means nucleus.
The prokaryotic cells are the primitive cells which lack an envelope enclosed nucleus and other membrane bound organelles. Mitochondria, endoplasmic reticulum, Golgi bodies, and lysosomes are absent in prokaryotic cells. However, mesosomes and ribosomes are present in prokaryotic cells. The prokaryotic cells have an irregular-shaped nucleoid region that contains the cell DNA and is not surrounded by the nuclear envelope.
Ribosomes are the minute particles that are present in large numbers consisting of RNA and proteins that function to synthesize proteins, or we can say that ribosomes are the molecular machines responsible for protein synthesis. The proteins are required in many cellular functions such as repairing damage and in the chemical process.
Since their membrane-bound organelles are absent in prokaryotic cells, the ribosomes float freely in the cytoplasm. Ribosomes are made up of two subunits, one is large and one small and they only bind together during protein synthesis. The function of ribosomes is to take the actual message and charged aminoacyl-tRNA complex to generate the protein.
All prokaryotes have 70S (where S stands for Svedberg units) ribosomes and this is made up of 50S and 30S subunits. The 50S subunit made up of 23S and 5S rRNA while the 30S subunit is made up of 16S rRNA.

The largest subunit of ribosomes in prokaryotic cells is option (C), 50S.

Note: The 50S subunit acts as the site of inhibition of antibiotics like chloramphenicol and clindamycin.
The small subunit 30S is used for binding and reading of mRNA during the process of translation.