biochemical pathways

• Enzymes


  Regulate biochemical pathways
• Metabolism


  The set of all biochemical reactions that sustain life
• Activation energy


  Chemical reactions will only occur if there is sufficient energy behind the reaction
• Metabolic processes


  • Most occur as a sequence of reactions
  • Can be linear, branched (many final products) or cycles
• Photosynthesis and cellular respiration


  • Both contain cyclic biochemical pathways in their reactions
• Photosynthesis


  Plants trap light energy and convert it into chemical energy which they store in the bonds of glucose molecules
• Photosynthesis


  Endergonic reaction (requires energy, anabolic, small -> large)
• Photosynthesis

  1. Light-dependent stage that converts light energy into chemical energy (ATP)

  2. Light-independent stage that uses the chemical energy (ATP) to synthesise organic compounds (glucose)
• Cellular respiration

  Cells obtain energy through releasing energy from organic compounds through biochemical pathways
• Cellular respiration

  Exergonic reaction (releases energy, catabolic, large -> small)
• Cellular respiration

  The combination of biochemical pathways that release energy from glucose
• Cellular respiration

  1. Glycolysis

  2. Krebs cycle

  3. Electron transport chain
• In absence of enzymes, reactions in these pathways would be very slow and cells would not be able to carry out essential functions
• Coenzyme

  • Structurally altered during reaction but can revert back
  • Can transfer protons, electrons and/or chemical groups from one molecule to another
• Cofactor

  • Additional non-protein components to enable enzymes to catalyse a reaction
  • Bind to the enzyme before the substrate
• Important coenzymes

  • Adenosine triphosphate (ATP)
  • Nicotinamide adenine dinucleotide (NADH)
  • Nicotinamide adenine dinucleotide phosphate (NADPH)
  • Flavin adenine dinucleotide (FADH2)
• ATP

  • Energy-rich compound
  • Energy is released when ATP IS hydrolysed into adenosine diphosphate
• NADH

  Moves protons and electrons between chemical reactions involved in cellular respiration
• NADPH

  Involved in photosynthesis
• ADP and ATP

  • ATP provides the energy required to drive most processes in living cells
  • Contains 3 phosphate molecules (3rd is held by a relatively weak, unstable bond)
  • When 3rd phosphate breaks off, ADP + inorganic phosphate is formed -> releasing energy
  • Reversible as ADP + phosphate -> ATP using the energy derived from breakdown of glucose during cellular respiration
• Hydrogen and electron carriers

  • NAD+/NADH and FAD+/FADH2 -> involved in transfer of protons and electrons from hydrogen
  • NADP+/NADPH -> carrier involved in nucleic acid synthesis/coenzyme used in photosynthesis + ATP
  • Unloading high energy electrons allow energy to be released when required -> drives high-energy steps in biochemical pathways -> eg. Synthesis of ATP
  • They free protons from organic molecules
  • Transport hydrogen
• Adenosine triphosphate

  ADP + inorganic phosphate
• Nicotine Adenine Dinucleotide

  NAD+
• Nicotine Adenine Dinucleotide Phosphate

  NADP+