Cell Biology

• Active transport


  The movement of molecules from an area of LOW concentration to an area of HIGH concentration against the concentration gradient
• Active transport requires energy
• DNA

  • Double stranded helix
  • Carries the genetic information to make proteins
• Gene


  A section of DNA that codes for ONE protein
• DNA sequence


  The sequence of bases in DNA determines the amino acid sequence in a protein
• Substrate


  The reactant that an enzyme will work on
• Product

  The substance formed during a chemical reaction
• Enzyme action

  Enzyme is placed above the arrow of the chemical reaction being catalysed
• Active site


  The special site on the enzyme where the substrate molecule fits
• Enzyme-substrate complex


  Forms when the substrate fits into the active site, facilitating the reaction
• Active site and substrate

  • Complementary in shape, allowing the substrate to fit into the enzyme
• Enzyme

  • Catalyses only one specific reaction, just like a key will only work on a specific lock
• Insulin

  For the treatment of diabetes
• Factor VIII


  For the treatment of haemophilia
• Vitamin A


  Genetically engineered in rice
• Glucose breakdown


  1. Bonds are broken

  2. Energy is released
• ATP

  Energy rich molecule that the body can use
• Producing ATP


  1. Breakdown of glucose

  2. Build up ATP from ADP and Pi
• Using ATP


  1. Break down ATP into ADP and Pi

  2. Release energy

  3. Use energy for cellular processes
• Cellular processes that use energy

  • Protein synthesis
  • Cell division
  • Muscle contraction
  • Transmission of nerve impulses
• Some energy is also lost as heat
• Aerobic respiration


  The breakdown of glucose in the presence of Oxygen
• Aerobic respiration


  1. Glucose → Pyruvate

  2. Pyruvate → Carbon Dioxide + Water
• Aerobic respiration Stage 1 yields a small quantity of ATP
• Aerobic respiration Stage 2 (oxygen required) yields a large amount of energy
• The products of aerobic respiration are carbon dioxide and water, completing the full breakdown of glucose
• Fermentation in animals


  The breakdown of glucose in the absence of oxygen
• Fermentation in animals


  Glucose → Pyruvate ↔ Lactate
• The reaction of fermentation in animals is reversible, and lactate can be converted back into pyruvate in the presence of oxygen
• Fermentation in animals


  • Only takes place in the cytoplasm
  • Only releases a small amount of energy, enough to produce only the initial 2 molecules of ATP
• Fermentation in plants and fungal cells


  Breakdown of glucose in the absence of oxygen
• Glucose


  Broken down to
• Products of fermentation


  • Ethanol
  • Carbon dioxide
• The reaction is not reversible due to the loss of carbon dioxide
• Fermentation


  • Only takes place in the cytoplasm
  • Only releases a small amount of energy, enough to produce only the initial 2 molecules of ATP