ch4 enzymes and metabolism

• Metabolism


  Sum of the chemical reactions that take place in an organism
• Catabolism


  1. Breaking down + energy release

  2. Complex molecules broken down into simpler molecules

  3. Respiration
• Anabolism


  1. Building up : energy required

  2. Simpler molecules synthesized into complex molecules

  3. Photosynthesis
• Enzyme


  Biological catalyst
• Enzyme


  • Lower activation energy (energy you need to supply reactants to start a reaction)
  • Enzyme lower activation energy —> reaction can take place at body temperature
  • Help remove hydrogen peroxide (toxic by product)
  • No enzyme —> slow reaction, toxic accumulate and kill our cells
  • Hydrogen peroxide —catalase—> oxygen+water
  • With catalyse —> 10^14 times faster
• Active site


  Binds to substrate molecules during reaction
• Active site


  • Specific shape —> only substrate molecules that fit their shape can bind to them
• Catabolic reaction


  1. Substrate molecule bind to enzyme —> enzyme-substrate molecule —> greatly lowers activation energy

  2. Substrate molecule converted into product

  3. Product leaves the site

  4. Back to original form, can be reused
• Catabolic


  Split apart
• Anabolic


  Join together
• Enzymes


  • Biological catalysts
  • Speed up metabolic reaction by Lower down activation energy
  • Enzyme are protein
  • Denatured at high temperature
  • Structure / activity Affected by extreme temperature / pH
  • Only substrate that binds to the site have reaction
  • Each enzyme catalyse one type of reaction only
  • Unique active site
  • Site of reaction does not change
  • Can be reused
  • Needed in small amounts
• Low temperature


  Enzyme inactive
• Temperature increase


  Kinetic energy increase, more chance to collide, more chance to form enzyme-substrate complex
• High temperature


  Enzyme activity decreases
• Low / high pH

  Enzyme activity decrease
• Optimum temperature


  Best works
• Optimum pH


  Activity at its maximum
• Optimum pH


  • Mammals (salivary amylase) pH 7
  • Pepsin: pH 2
  • Pancreatic lipase: pH 9
• Inhibitors


  Substance that decrease the activity of enzyme
• Inhibitors


  • Cyanide
  • Heavy metal (Mercuric irons, lead, ions)
• Cyanide


  • Prevent Respiration
  • Prevent the enzyme from working properly
• Heavy metal


  Affect metabolism