Question

Select the statement which is not true for ribosomes.
(a)Made of two subunits
(b)Form polysome
(c)May attach to mRNA
(d)Have no role in protein synthesis.

Answer 1

Ribosomes are particles or cell organelles consisting of mainly RNA and protein. It serves as a site for protein synthesis. They have two subunits bound together by tRNA interactions. Both prokaryotic and eukaryotic cells contain ribosomes, as it is an essential organelle for protein production to occur.

Complete answer:
Ribosomes do not have any role in protein synthesis. Ribosomes consist of two subunits. Eukaryotic cells contain 80S ribosome which is made of 60S and 40S subunits whereas the prokaryotic, as well as mitochondria and chloroplast ribosome, have two subunits 50S and 30S which ultimately make a 70S ribosome. Ribosomes may form polysomes during which many ribosomes are attached to mRNA. The purpose of this is to synthesize proteins but ribosomes do not have a direct role in the synthesis.

Additional Information: -Ribosomes are cell organelles that are the sites of protein production from amino acids. This process is called protein synthesis.
-These are found in both prokaryotic and well as eukaryotic cells. The ribosome is essential for every organism to produce proteins.
-These functions by binding to a messenger Ribonucleic acid or mRNA. The tRNA or transfer RNA enters the ribosome at the acceptor site. After binding it adds amino acids to the growing protein chains on tRNA.
-Ribosome is a complex of RNA and protein, made of two subunits, one smaller than the other. The mRNA is decoded in the smaller unit and the larger one, amino acids get added. These two are joined together by interactions between the tRNA.
-Only 28% of the ribosome is made of protein. The other part is made of RNA.
-The main function of the ribosome is the translation of mRNA encoded genetic information into protein.
So, the correct answer is ‘Have no role in protein synthesis.

Note: Even though the ribosome is an essential organelle to produce proteins, it has no direct role in protein synthesis. It translates the mRNA encoded genetic information into proteins. It moves along a molecule of mRNA reading one codon at a time. It results in the incorporation of one amino acid into a longer protein chain. The tRNA or transfer RNA then brings the amino acids to the ribosome. Thus, the ribosome can recognize and bind the perfect word for nucleic acid specified by the tRNA anticodon with the amino acid attached to it. The translation stops, ribosomal subunits separated and detached from the mRNA, and the completed protein releases, when the ribosome reaches a stop codon.