Nucleosidi

Nucleosidi are organic molecules consisting of a nucleobase linked to a sugar. The sugar can be either ribose or deoxyribose. When a nucleobase is linked to ribose, the resulting molecule is a ribonucleoside, and when linked to deoxyribose, it is a deoxyribonucleoside.

The nucleobases commonly found in nucleosidi are adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). Adenine, guanine, cytosine, and thymine are found in deoxyribonucleosidi, while adenine, guanine, cytosine, and uracil are found in ribonucleosidi. In DNA, the deoxyribonucleosides are deoxyadenosine, deoxyguanosine, deoxycytidine, and deoxythymidine. In RNA, the ribonucleosides are adenosine, guanosine, cytidine, and uridine.

Nucleosidi are the building blocks of nucleic acids, DNA and RNA. In DNA and RNA, nucleosidi are linked together by phosphodiester bonds to form polynucleotide chains. The sequence of nucleobases in these chains carries the genetic information of an organism.

Beyond their role in nucleic acids, nucleosidi and their derivatives have various biological functions. For example, adenosine is a neurotransmitter and plays a role in regulating sleep and blood flow. ATP (adenosine triphosphate) is a crucial energy currency in cells. Some nucleoside analogs are used as antiviral and anticancer drugs because they can interfere with viral or cancer cell replication.