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What are Nucleosides, Nucleic Acid, Nucleotides

“Nucleic acid” is found within the name of DNA (Deoxyribose nucleic acid) and RNA (Ribose nucleic acid), but aren’t DNA & RNA made up of nucleotides?


is the ribose or deoxyribose sugar bound with a nitrogenous base (purine or pyrimidine) without the attachment of a phosphate group


is made of:

1. Five carbon sugar also known as a pentose (pent = five) sugar. This pentose, or five carbon sugar, may either be deoxyribose or ribose. The difference between the two is at the 2nd carbon of the five ring structure. If there is NO “OH” or hydroxyl group attached to that 2nd carbon, it is called a deoxyribose. If there is an “OH” or hydroxyl group attached, it is called a ribose.

2. A tri-phosphate group attached at the 5’ carbon of the pentose

3. A base attached at the 1’ carbon atom of the pentose. This base isn’t just any base, it is a Nitrogen containing ring structure, and can be either purines or pyrimidines.

Purines (found in both RNA and DNA)



Pyrimidines (in DNA)


Thymine (not in RNA)

Uracil ?(found in RNA)

Examples of nucleotides in DNA are: dAMP, dGMP, dCMP, dTMP.

dATP isn’t considered a nucleotide because there are three phosphate groups instead of one.

Examples of nucleotides in RNA are AMP, GMP, CMP, TMP.

Note: d = deoxy (describing the sugar, ribose), AMP = adenosine mono phosphate, GMP = guanine mono phosphate, CMP = cytosine mono phosphate, TMP = thymine mono phosphate Nucleic Acid


This is a sequence of nucleotides covalently bound together. The result is an alternating sugar to phosphate sequence found as the backbone of the DNA or RNA strand. Since each nucleotides are acidic, it is rational to say that a series of these nucleotides would give you an acidic polymer (nucleic acid).

Quick Review: What is the structural difference between RNA and DNA?

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