Question

Why is mRNA the least stable?

Answer 1

It is primarily engaged in protein synthesis, conveying messenger instructions from DNA, which provides the genetic information necessary for life's development and maintenance. RNA, rather than DNA, carries genetic information in some viruses. DNA and RNA are two different forms of nucleic acid. Deoxyribose is the nucleic acid of DNA, whereas ribose is the nucleic acid of RNA.

Complete answer:
Because mRNA is unstable and short-lived in cells, especially in bacterial cells, proteins are only produced when they are needed. Although neither of these forms of RNA carries instructions for polypeptide synthesis, they do play crucial functions in protein synthesis.
Because of chemistry, RNA is generally unstable. The absence of the hydroxyl group in DNA is significant. DNA stands for 2 deoxyribonucleic acids.
The phosphodiester bond is unstable and sensitive to nucleophilic attack and self-hydrolysis since RNA has the typical 2 hydroxy group.
When RNA is single stranded (as in mRNA), the 2-hydroxy group can reach the phosphorus atom more easily, cutting the chain. When RNA is in the form of a double helix (as in tRNA and many rRNA components), mobility is restricted, and the hydroxyl group cannot reach the phosphorus as quickly. As a result, RNA molecules with a double helix structure are far more stable. Because mRNA is often unstructured, it is less stable.

Note:-
The existence of cis-elements inside an mRNA, which can be bound by trans-acting RNA-binding proteins to suppress or enhance mRNA decay, determines the stability of a certain mRNA transcript.In comparison to RNA's ribose sugar, DNA's deoxyribose lacks one oxygen molecule. Adenine (A), guanine (G), cytosine (C), and thymine (T) are the nucleotides that make up DNA, while A, G, C, and uracil are the nucleotides that make up RNA (U).