Respiration

• Respiration

  • Cellular respiration: Organic macromolecules oxidation to release energy
  • Photoautotrophs, producer: plants, some protoctists + some bacteria
  • Heterotrophs, consumers/decomposers: animals, fungi + most bacteria
  • All organisms respire
  • Transfer potential chemical energy of carbs, lipids + proteins to chemical (ATP) + thermal energy
  • Important to maintain cell temperature (for enzyme-controlled reactions)
  • Oxidation: Breakdown by O_2 or elecron/H+ removal
  • Reduction: Electron addition; metabolic pathway, can involve H+ addition
  • Oxidoreductases: Enzyme groups which catalyse oxidation-reduction (redox) reactions
  • Hydrolases: Enzyme groups which catalyse hydrolysis reactions
  • ATP (adenosine triphosphate)
  • Central metabolism molecule
  • Main respiratory product
  • Can't move around body
  • Continuously produced
  • ‘Universal energy carrier’
  • Has phosphate groups for metabolic pathways + enzyme activation
• Metabolism

  • Sum of all enzyme-controlled chemical reactions in a living organism
  • Metabolic pathway is reaction sequence resulting in formation of 1 substance (product) from different 1 (substrate)
  • Catabolic reaction: Breakdown of organic molecules; most exergonic - release chemical energy + involve oxidation or hydrolysis
  • Anabolic reactions: Synthesis of small molecules to form larger ones, are endergonic - absorb chemical energy + involve condensation
  • Metabolites converted to products in series of small reactions
  • Large catabolic reactions create unfavourable life conditions
  • Substances partially broken down for raw materials
  • Organic compounds complex
  • Synthesis impossible in 1 step w/ simple raw materials + small steps in anabolic pathway control product production
• Respirometer

  • Several methods to indirectly measure cellular respiration rate in organisms
  • Like monitoring temp changes (since process exergonic)
  • Or measure either O_2 consumption or CO_2 production
  • Respirometers measure gas vol changes + so provide info on cellular respiration rate
  • Sodium hydroxide (or potassium hydroxide) absorbs all CO_2 from apparatus beginning
  • Respiring insect uses O_2, pressure reduces in tube A + manometer level nearest to insect moves up
  • Any CO_2 excreted absorbed by sodium hydroxide solution + syringe returns manometer fluid levels to normal
  • O_2 vol used is calculated by measuring gas vol needed from syringe to return levels to original