Nucleosides, Nucleotides and Nucleic Acids

1) A nucleoside (with an s) consists of a nitrogenous base covalently attached to a (ribose or deoxyribose) sugar but without the phosphate group.

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2) A nucleotide (with a t) consists of a nitrogenous base, a sugar, and a phosphate group. So, a nucleotide is a “nucleoside mono-phosphate.”

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3) A nucleic acid contains a chain of nucleotides covalently linked together to form a sugar-phosphate backbone with protruding nitrogenous bases. In RNA (ribonucleic acid), the sugar groups are ribose, whereas in DNA (deoxyribonucleic acid), deoxyribose sugars are present instead of ribose.

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reference

“Nucleic Acid VS Nucleotide,” Newton; accessed on april13,2013. http://www.newton.dep.anl.gov/askasci/mole00/mole00296.htm.