Question

Assertion:
Ribosomes are non-membrane bound organelles found in the prokaryotic cells only.
Reason:
Ribosomes are present only in the cytoplasm
(a) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
(c) Both Assertion and Reason are incorrect.
(d) Both Assertion and Reason are correct.

Answer 1

Hint: Ribosomes are macromolecules consisting of RNA and associated proteins found in living cells. They perform biological protein synthesis. Ribosomes are found in the cytoplasm, chloroplasts (in plants), and mitochondria and on rough endoplasmic reticulum (ER).

Complete answer:
Claude was the first to isolate the ribosome in 1983A.D. Ribosomes were first reported in the root cells of broad beans. Ribosomes are non-membrane bound organelles found in all living cells i.e. both in eukaryotic as well as prokaryotic. The cell organelles having no membrane are called non-membranous or naked cell organelles. Membrane-less cell organelles lie mixed within the nucleoplasm or cytoplasm due to the lack of their membrane. Prokaryotic cells are cellular organisms that lack an envelope-enclosed nucleus or true nucleus and are abundant thus make up much of Earth's biomass. Examples are blue-green algae, bacteria, and mycoplasma. Based on the sedimentation coefficient, ribosomes are of two types- 70S ribosomes made of 50S and 30S submits, and 80s ribosomes. Prokaryotic cells are of the first type and eukaryotic cells are of the second type.
Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum of the eukaryotic cells. The prokaryotic ribosomes are slightly smaller compared to the eukaryotic ribosomes. It was seen that there are no ribosomal proteins close to the reaction site for polypeptide synthesis. This suggests that these proteins act as a scaffold that may enhance the ability of rRNA to synthesize protein.
So, the correct answer is ‘Both Assertion and Reason are incorrect'.

Note: Ribosomes of prokaryotic cells are around 20 nanometres or 200 angstroms in diameter and are composed of 65% rRNA and 35% proteins of ribosomes whereas eukaryotic ribosomes are between 25 and 30 nanometres.