NUCLEOTIDES: STRUCTURE, CLASSIFICATION AND FUNCTIONS
LECTURE OBJECTIVES
At the end of lecture the student should be able to;
• Describe nitrogenous bases present in the nucleic acids
• Describe the structure of nucleoside and nucleotides
• Discuss the functions of nucleotides (energy carrier, coenzymes, electron carrier,
metabolite activator, nucleic acids, information transfer)
• Explain polymerization of nucleotides via 3’-5’ phosphodiester bonds
• Justify that the nucleotide polymers have a direction fro 5’ to 3’
NITROGENOUS BASES
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Non protein
Made form proteins
Cyclic compounds having nitrogen
Purines
– Two rings
Pyrimidines
– One ring
SUGAR AND PHOSPHATE
NUCLEOSIDE AND NUCLEOTIDE
Nitrogenous base + sugar
Nitrogenous base + sugar + phosphate group
STRUCTURES OF NUCLEOSIDES
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Sugar
– Ribose
– Deoxyribose
Base
– Purine
– Pyrimidine
Name
– AdininineAdinosine
– Guanine
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STRUCTURES OF NUCLEOTIDES
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Sugar
– Ribose
– Deoxyribose
Base
– Purine
– Pyrimidine
Phosphate
– One-mono
– Two-Di
– Three-Tri
NUCLEOSIDE AND NUCLEOTIDE
FUNCTIONS OF NUCLEOTIDES
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Energy carriers
Electron carriers
Coenzymes
Activation of metabolites
Expression of genetic information
Transmission of genetic information
Nucleotide: Energy Carrier
Phosphate anhydride bond
High energy
~7.4Kcal/mol
ELECTRON CARRIERS
CO-ENZYMES
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Assist the enzymes
– Pyruvate dehydrogenase
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Electron acceptors
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NAD, NADP
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FAD
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FMN
PYRUVATE DEHYDROGENASE
ACTIVATION OF METABOLITES
ACTIVATION OF METABOLITES
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EXPRESSION OF GENETIC INFORMATION:
NUCLEIC ACIDS
Nucleotides polymerize
3’-5’phosphodiester bonds
Sugar phosphate back bone
Bases project inward
DNA and RNA
Nitrogenous bases differ
EXPRESSION OF GENETIC INFORMATION
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ORGANIZATION OF GENETIC MATERIAL
Sugar Phosphate Backbone
– Hydrophilic
Phosphodiester Bond
Bases Project Inward
– Hydrophobic
NUCLEIC ACIDS
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Nucleotides polymerize
Sugar phosphate backbone
Phosphodiester bond
Nucleic Acids have 5’ to 3’ direction because the phosphodiester bond are formed from 3’ – 5’
direction.
DNA AND RNA
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