RNA is a polymer of ribonucleotides held together by 3 ,5 –phosphodiester bridges.

Although RNA has certain similarities with DNA structure ,they have several specific differences.

1.Pentose The sugar :in RNA is ribose in contrast to deoxyribose in DNA.

2.pyrimidine: RNA contains the pyrimidine uracil in place of thymine

3.Single strand: RNA is usually a single stranded polynucleotide. How ever, this strand may fold at certain places to give a double stranded structure, if complementary base pairs are in close proximity.

4.chargaff”srule – not obeyed : Due to the single- stranded nature, there is no specific relation between purine and pyrimidine contents.

Thus the guanine contents is not equal to cytosine(as is the case in DNA)

5.Susceptability to alkali hydrolysis : Alkali can hydrolyze RNA to 2,3-cyclic diesters.

This is possible due to the presence of a hydroxyl group at 2 position.

DNA cannot be subjected to alkali hydrolysis due to lack of this group.

6.Orcinol color reaction :RNAs can be histologically identified by orcinol color reaction due to the presence of ribose.

Types of RNA: mRNA, rRNA and tRNA

RNA or ribonucleic acid is a polymer of nucleotides that is made up of a ribose sugar, a phosphate, and bases such as adenine, guanine, cytosine, and uracil.

It plays a crucial role in gene expression by acting as the intermediate between the genetic information encoded by DNA and protein RNA has a structure very similar to that of DNA.

The key difference in RNA structure is that the ribose sugar in RNA possesses a hydroxyl (-OH) group that is absent in DNA.

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