Question

Why ribosomes don't have a membrane ?

Answer 1

Hint: A ribosome is a cellular organelle made of RNA and protein that serves as the site for protein synthesis in the cell. The ribosome reads the sequence of the messenger RNA (mRNA) and, using the genetic code, translates the sequence of RNA bases into a sequence of amino acids. Ribosomes have two primary functions: message decoding and peptide bond synthesis.

Complete answer:
Ribosomes are simply really huge, composite macromolecules made up of RNA and proteins.

They are made up of rRNA and other proteins. They lack a lipid bilayer and do not compartmentalise anything; they are simply a big structure made up of a number of gene products (lots of ribosomal proteins, as well as strands of rRNA, which is the enzymatic component). They are, in essence, very enormous enzymes.

Ribosomes are non-membrane bound organelles that can be found in both eukaryotic and prokaryotic cells. Ribosomes can be located not only in the cytoplasm of the cell, but also in the two organelles chloroplasts (in plants) and mitochondria, as well as on rough endoplasmic reticulum.

They don't require a membrane to function, hence they aren't equipped with one. Moving mRNA, tRNA, and proteins into and out of the ribosome would be much more complex and energy-intensive if they possessed a membrane or we can say that lack of membrane allows them to pick up translational RNA released from the nucleus and grab onto free amino acids in order to produce protein chains.

Other organelles without membranes exist in eukaryotes, such as centrioles, the cytoskeleton, and undulipodia.

Note:-
Ribosomes can be seen floating around in the cytoplasm or bound to the endoplasmic reticulum to create rough ER. There can be up to 10 million ribosomes in a mammalian cell. A polysome is a structure that consists of several ribosomes coupled to the same mRNA strand. Ribosomes are only present for a short time. When a polypeptide is synthesised, the two subunits split and are either re-used or broken up.