IB DP Biology: SL复习笔记2.1.2 Metabolism

Metabolism

  • Metabolism is a catch-all term used to describe all the chemical reactions that take place within cells and organisms
  • Metabolism can be thought of as the chemical reactions of life
    • The molecules involved are metabolites
  • Many reactions of metabolism take place in multiple stages
    • Each stage is catalysed by a separate enzyme
  • A series of interlinked metabolic reactions is called a metabolic pathway
  • Metabolic reactions can be classified broadly as anabolic or catabolic

Anabolism

  • Anabolic reactions are involved with the building of large molecules from smaller ones
  • Examples include;
    • Photosynthesis, where CO2 and water are built up into complex sugars
    • Protein synthesis, where amino acids are joined together in sequence
    • The buildup of fat stores ahead of animal hibernation
  • Anabolic reactions often include condensation reactions
  • Anabolic reactions are endergonic (they require an input of energy to take place)
    • Energy-storing products are the end result

Catabolism

  • Catabolic reactions are involved with breaking down large molecules into smaller ones
  • These reactions are often carried out to release energy for cellular processes and for the excretion of waste
  • Examples include:
    • Respiration, where CO2 and water are produced from the breakdown of sugars
    • Deamination of proteins to release urea
    • The depletion of fat stores during animal hibernation
  • Catabolic reactions often include hydrolysis reactions
  • Catabolic reactions are exergonic (free energy is released for cellular processes or as excess heat)

Comparison of Anabolism and Catabolism Table

Comparison-of-Anabolism-and-Catabolism-Table

Exam Tip

You may be familiar with the concept of anabolic steroid drugs used by bodybuilders. This is to build muscle mass and so is a good example to remember when trying to remember the difference between anabolic and catabolic reactions.

 

 

 

 

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