1.3 1

• Nucleotides


  Key molecules in biology that provide the energy currency of cells in the form of ATP, and the building blocks for DNA and RNA
• Nucleotides


  • Have three parts: a 5-carbon pentose sugar, a nitrogen-containing base, and a phosphate group
  • The pentose sugar in RNA is ribose, and in DNA is deoxyribose
• Types of nucleotide bases

  • Purines (adenine, guanine)
  • Pyrimidines (cytosine, thymine, uracil)
• Phosphate group


  Makes nucleotides acidic molecules that carry a negative charge
• Formation of nucleotides


  Sugar, base and phosphate group joined together by condensation reactions
• ATP (Adenosine Triphosphate)


  The universal energy supply molecule in cells, found in all living organisms
• ATP


  • Has three phosphate groups attached
  • The potential energy in the phosphate bonds is made available to cells for use in breaking bonds in chemical reactions
• Breakdown of ATP


  1. Catalysed by the enzyme ATPase

  2. Produces ADP (Adenosine Diphosphate) and a free inorganic phosphate group

  3. Releases about 34kJ of energy per mole of ATP hydrolysed
• Breakdown of ATP


  Provides energy for energy-requiring biological activities in the cell
• Synthesis of ATP


  1. From ADP and a phosphate group, catalysed by ATPase

  2. Requires an input of 30.5kJ per mole of ATP produced
• Synthesis of ATP


  Usually driven by breakdown reactions or reduction/oxidation (redox) reactions
• Cyanide is a poison that blocks part of the process of cellular respiration producing ATP, leading to cell death
• Adenosine Diphosphate (ADP)


  Nucleotide formed when ATP loses a phosphate group and provides energy to drive reactions in the cell
• Reduction/oxidation (redox) reactions


  Reactions in which one reactant loses electrons (is oxidised) and another gains electrons (is reduced)