Both the purine and pyrimidine bases can undergo keto-enol tautomerism In certain of the bacterial viruses cytosine is replaced by 5-methylcytosine or 5-hydroxymethylcytosine. NUCLEIC ACIDS: STRUCTURE and FUNCTION The bases, Adenine, Guanine and Cytosine are found in both DNA and RNA. NUCLEIC ACIDS: STRUCTURE and FUNCTION Pyrimidine bases The pyrimidine bases are derivatives of the parent compound pyrimidine and includes = thymine,cytosine and uracil. The bases are planar, aromatic, heterocyclic molecules. The Nitrogenous bases, which is either Pyrimidine or a Purine derivative.
NUCLEIC ACIDS: STRUCTURE and FUNCTION Each nucleotide is composed of three components: MONOMERIC COMPONENTS 1. On complete hydrolysis nucleic acids yields pyrimidine and purine bases, a sugar component and phosphoric acid. The chain-like macromolecule is made up of strings of monomeric units called nucleotides. NUCLEIC ACIDS: STRUCTURE and FUNCTION DNA and RNA Both deoxyribonucleic acid(DNA) and ribonucleic acid(RNA) are high-molecular-weight polymeric compounds. By 1920, two forms of nucleic acids were differentiated: The Structure of Nucleic Acids The chemistry of DNA has been studied since 1868 and by 1900 the basic chemistry of nucleic acids was worked out. NUCLEIC ACIDS: STRUCTURE and FUNCTION In the eyes of the critic, it threatens to undermine privacy and brings on genetic discrimination in insurance and employment. It is the letters ATCG… on and on for about 3.2 billion of such letters that provides the information. Scientist will learn which genes turn on when a wound heal. NUCLEIC ACIDS: STRUCTURE and FUNCTION In the foreseeable future, medical doctors will drip droplets of our genes onto a biochip to figure out if we have the kind of prostrate cancer that will kill or not. The information is hoped, will revolutionize the detection, prevention and treatment of conditions from cancer to depression to old age itself. The Human Genome Project where over 90% (99.9% accuracy) of the 3.2 billion nucleotideshave been cloned and sequenced. NUCLEIC ACIDS: STRUCTURE and FUNCTION Why study nucleic acids? DNA is the focus of attention because of its role in carrying and expressing genetic information. NUCLEIC ACIDS: STRUCTURE and FUNCTION Objectives: At the end of these lectures you should be able to describe: - The types of nucleic acids - The structure of nucleic acids - The base composition of DNA - The conformations of DNA - The functions of nucleic acids
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