Editing Ribonucleotide (section)

===DNA deoxyribonucleotides versus RNA ribonucleotides===

In ribonucleotides, the sugar component is ribose while in deoxyribonucleotides, the sugar component is deoxyribose. Instead of a hydroxyl group at the second carbon in the ribose ring, it is replaced by a hydrogen atom.<ref>{{cite book |last1=Newsholme |first1=Eric A. |last2=Leech |first2=Anthony R. |last3=Board |first3=Mary |title=Functional biochemistry in health & disease: metabolic regulation in health and disease |year=2008 |publisher=Wiley |location=Hoboken, N.J. |isbn=978-0-471-98820-5 |edition=2nd}}</ref>

Both types of pentoses in DNA and RNA are in their β-furanose (closed five-membered ring) form and they define the identity of a nucleic acid. DNA is defined by containing 2'-deoxy-ribose nucleic acid while RNA is defined by containing ribose nucleic acid.<ref name=Nelson08 />

In some occasions, DNA and RNA may contain some minor bases. Methylated forms of the major bases are most common in DNA. In viral DNA, some bases may be hydroxymethylated or glucosylated. In RNA, minor or modified bases occur more frequently. Some examples include hypoxanthine, dihydrouracil, methylated forms of uracil, cytosine, and guanine, as well as modified nucleoside pseudouridine.<ref>{{cite book|last=Das|first=Debajyoti|title=Biochemistry|year=2010|publisher=Bimal Kumar Dhur of Academic Publishers}}</ref> Nucleotides with phosphate groups in positions other than on the 5' carbon have also been observed. Examples include ribonucleoside 2',3'-cyclic monophosphates which are isolatable intermediates, and ribonucleoside 3'-monophosphates which are end products of the hydrolysis of RNA by certain ribonucleases. Other variations include adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP).<ref>{{cite book |last1=Cox |first1=Michael M. |last2=Nelson |first2=David L. |title=Principles of Biochemistry |year=2008 |publisher=W H Freeman |isbn=978-1-4292-2263-1 |oclc=216940502}}</ref>