Organic chemistry for medicine and biology students
Chem 2311
Chapter 18Nucleotides and Nucleic acids
By Prof. Dr.Adel M. Awadallah
Islamic University of Gaza
Nucleic acids (DNA & RNA) are linear, chain macromolecules that were first isolated from cell nuclei.
They have a backbone of sugar molecules, each with a base attached, connected by phosphate links.
NucleosidesN-Glycosides
A nucleoside is an N-Glycoside. The pyrimidine or purine base is connected to the anomeric carbon of the sugar.
The pyrimidines are connected at N-1 and the purines are connected at N-9.
Nucleosides are water soluble. They can be hydrolyzed by aqueous acid or enzymes to the sugar and heterocyclic base
The primary structure of DNA
Sequencing Nucleic Acids • The smallest DNA molecules contains at least 5000 nucleotide units• Some contains 1 million or more nucleotide units• The strategy relies on breaking the DNA into small identifiable
fragments using a combination of enzymatic (restriction endonucleases) and chemical reactions
• Sangar (born 1918) sequenced a virus • Chromosome with 5375 nucleotide units • 1958 he was awarded a Nobel prize in chemistry “• for his work on the structure of proteins, • especially that of insulin"• In 1980, Walter Gilbert and Sanger shared half of the chemistry prize "for their
contributions concerning the determination of base sequences in nucleic acids".
• 1985 sequence 170,000 nucleotide unit
Secondery Structure of Nucleic Acids
* Two right handed helices• 10 base pairs for every turn• A = T and G = C• Human DNA• A = B = 30 % each• G = C = 20 % each
A = T and G = C
DNA Replication
The Polymerase chain reaction PCR
• PCR is a technique for making many copies of a specific DNA sequence (amplification)
