Nucleotides and nucleic acids

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Nucleotides and nucleic acids

• Nucleotides small molecules
• Components of nucleic acids
• Energy storage (eg. ATP)
• Signal transduction/info transfer (eg. cAMP)
• Components of coenzymes (eg. NADH)
• Nucleic acids polymers
• Major role information transfer
• DNA genetic information
• RNA translate genetic info into protein 1
  structure messenger RNA
• Component of proteins
• eg. ribosomes
• Other RNA-containing proteins (mRNA splicing)
• Enzyme
• ribozymes

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Nucleic acids are polymers of nucleotides

• Phosphate
• Nitrogenous base
• Sugar (pentose)

Nucleoside base sugar
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Nitrogenous bases
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Sugar (ribose/deoxyribose)
H
2 position Hydroxyl in ribose Hydrogen in deoxy-
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Phosphate group
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Phosphate group
Adenosine 5-triphosphate
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Polymerization via phosphodiester linkage
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Structure of DNA

• Double helix
• Discovered by Watson Crick, but also Franklin
  Wilkins (1940s/50s)
• Two strands running anti-parallel
• Contains large major groove and smaller minor
  groove
• H-bond donors/acceptors, protein binding

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Antiparallel
5
3
3
5
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DNA strands held together by weak interactions

• Watson-Crick base pairing
• A (purine) with T (pyrimidine)
• G (purine) with C (pyrimidine)
• Complementarity genetic information
• Non-specific interactions van der Waals forces
  stabilize helix formation via base stacking

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Watson-Crick base pairing

• A-T two H-bonds
• G-C three H-bonds
• More G/C content stronger bond between strands
  (melting temperature)
• Not all potential H-bonds are used areas for
  proteins, other molecules to bind (major/minor
  groove)

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Base pairing allows for information storage
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RNA

• Translates DNA information into protein sequence
• Messenger (mRNA)
• Charges amino acids for incorporation into
  polymerizing protein
• Transfer (tRNA)
• Part of the structure of ribosomes
• Ribosomal (rRNA)
• Other functions
• Small nuclear (snRNA)
• Genome (RNA viruses)
• Catalytic (ribozymes)

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RNA is typically single strandedstill has
complex 3D structure
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Three dimensional structure of RNA
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