Nucleic Acids: Composition and Types Explained

Quick answer: Nucleic acids are polymers of nucleotides that store and transmit genetic information. DNA stores it as a stable double helix, while RNA usually works as a single strand that reads, regulates, and helps build protein. Both rely on sugar, phosphate, and nitrogenous bases, joined by phosphodiester bonds that build the sugar phosphate backbone.

Know about nucleic acids their composition in detail

Of all the polymeric compounds found in living cells, and as vital components of living material, none are so important as the nucleic acids. Swiss physician Fredrich Miescher isolated a substance from pus cells and called it ‘Nucelin’. It was neither a protein, a lipid nor a carbohydrate. Being a novel type of biomolecule isolated from the nuclei of white blood cells with acidic properties, it was called Nucleic acid.

He also determined that the nuclein was made up of hydrogen, oxygen, nitrogen and phosphorous, and there was a unique ratio of nitrogen to phosphorus (N/P- 1.67). Later in the 1920s biochemist, Phoebus from Heidelberg analysed the DNA molecule that contained four nitrogenous bases cytosine, thymine, adenine and guanine; a deoxyribose sugar and a phosphate group and defined nucleotide as a phosphate-sugar base. He also figured the difference between ribose and deoxyribose sugar.

These are two general types, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These two can be differentiated by cellular location, molecular size, pyrimidine components and component sugars.

Nucleic acids are biopolymers of high molecular weights. Nucleic acids have nucleotides held together by a 3-5 phosphodiester linkage. Proteins have amino acids as monomers. Nucleic acids have mononucleotides as the repeating units. They gave 15% N₂ and 10% P. Nucleic acids are always associated with proteins. These are called nucleoproteins. Complete hydrolysis of nucleic acids gives phosphoric acid, bases and pentose.

Classification of Nucleic acids

Nucleoproteins made of simple proteins and nucleic acids.

Comparison of RNA and DNA

		RNA	DNA
1	On Hydrolysis	Phosphoric acid, D- Ribose, Adenine, Guanine, Cytosine, Uracil	Phosphoric acid, D-2 deoxyribose, Adenine, Guanine, Cytosine, Thymine
2	Location	Cytoplasm	The chromatin of the nucleus
3	Weak alkali at pH 9	Alkali labile forms cyclic monophosphate nucleotide	Alkali stable
4	Nature	Single-stranded, need not exhibit base complementarity	Double-stranded. Exhibited complementarity
5	Shape	Strand is folded at some places	Spirally twisted to produce a regular helix
6	Function	Involved in protein synthesis	Acts as genetic material
7	Types	Different forms are r RNA, t RNA, m RNA	Intra nuclear and Extracellular
8	Life span	Short life span	Long-lived

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