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2. Beskrive hvordan nukleosidanaloger kan bruges kemoterapeutisk
Devlin, s. 854
Devlin, s.166

Nucleoside - a base glycosylated with either pentose sugar. The four nucleoside units in RNA are adenosine, guanosine, cytidine and uridine, while in DNA deoxyadenosin, deoxyguanosine, deoxycytidine and thymidine.

Analogs to these nucleosides can be used in chemotherapy.

De novo synthesis of purine and pyrimidine nucleotides is critical for normal cell replication, maintenance and function. When a normal cell transforms into a cancer cell, our ultimate goal is to interrupt the intercellular processes to that degree that the cell eventually dies. One way of doing it, is to prevent it from replicating, by preventing its synthesis of the DNA and RNA building blocks.

For that purpose, nucleotide analogs can be used. Despite very high accuracy of polymerases, they can incorporate nucleotide analogs. Nucleoside analogs are often used in chemotherapy to kill rapidly growing cancer cells or viruses.

Analogs that are phosphorylated to nucleotides can be incorporated into DNA, where they can inhibit further synthesis or lead to high level of mutation.

Many compounds, both synthetic and natural products of plants, bacteria, fungi, are structural analogs of the bases or nucleotides used in metabolic reactions.  

Differences in the ability of viral or bacterial polymerases to incorporate nucleotide analogs can provide a therapeutic window, allowing physicians to target the infected cells.

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