Metabolism + Cellular Respiration

• Types of metabolism

  • Catabolic metabolism = large molecules broken down into smaller molecules
  • Anabolic metabolism = small molecules built into larger molecules
• Catabolic reactions

  Release energy (digestion)
• Anabolic reactions

  Require energy (protein synthesis)
• Nutrients

  • Water
  • Carbohydrates
  • Lipids
  • Proteins
  • Minerals
  • Vitamins
• Organic compounds

  Molecules that have a carbon chain
• Carbohydrates

  • Organic compound
  • Main source of energy for cells
  • Monosaccharides = 1 simple sugar (glucose)
  • Disaccharides = 2 simple sugars (sucrose)
  • Polysaccharides = more than 2 simple sugars (glycogen)
• Lipids


  • Organic compound
  • Fats + oils ->broken down into fatty acids and glycerol
  • Phospholipids -> cells membrane (steroids)
  • Triglyceride -> glycogen and 3 fatty acids (fat in body)
• Proteins


  • Organic compound
  • Proteins= amino acids (enzymes)
  • Dipeptide= 2 amino acids joined
  • Polypeptide= more than 10 amino acids joined
• Nucleic acids

  • Organic compound
  • DNA = 2 nucleotide chains with sugar deoxyribose -> stores inherited information
  • RNA = single strand nucleotide with sugar ribose
• Inorganic compounds


  No carbon chain except carbon dioxide
• Water


  • Site of some chemical reactions
  • The fluid in which other substances are dissolved in
• Minerals


  • Function as cofactors for enzymes
• Vitamins


  • Coenzymes for chemical reactions
• Enzymes


  • Catalysts that speed up chemical reactions by decreasing the amount of energy needed to break bonds
• Substrate


  The molecule on which an enzyme acts
• Active site


  The part of the enzyme molecule that combines with the substrate
• Enzyme-substrate complex


  Created when enzyme and substrate are combined
• Lock-and-key model


  • Enzyme= key
  • Substrate= lock
  • Shape of enzyme is always complementary to the substrate, creates enzyme-substrate complex
• Induced-fit model


  • When the enzyme and substrate join, they form weak bonds that cause the shape of the enzyme to change, creating complementary shapes
• Factors affecting enzyme activity


  • Enzyme concentration
  • Substrate concentration
  • Removal of products
  • Temperature
  • pH
  • Cofactors
  • Enzyme inhibitors
• Enzyme concentration 


  The higher the concentration of enzyme, the faster the rate of a chemical reaction because there are more enzyme molecules to influence reactants.
• Substrate concentration 


  Increasing substrate concentration also increases the rate of the reaction, because there will be more substrate molecules coming into contact with the enzyme molecules. If there are too many substrates it creates saturation, the reaction rate will plateau because the active sites on all the enzyme molecules will be fully occupied.
• Removal of Products

  The products of the reaction must be continually removed, otherwise the rate of the reaction will slow because it becomes more difficult for the substrate molecules to make contact with the enzyme molecules.
• Temperature

  • As the temperature increases the rate of reaction also increases
  • If temperature is above 45–50°C enzymes will denature
  • When enzymes denature the structure changes -> enzyme-substrate complex cannot be made
• pH 


  Each enzyme has optimal pH at which it will work most effectively
• Cofactors


  Cofactors change the shape of the active site so that the enzyme can combine with the substrate.
• Enzyme inhibitors


  Substances that slow or stop enzyme activity, used by cells to control reactions (penacillin)
• Cellular respiration


  The process by which organic molecules taken in as food are broken down in cells to release energy for the cells activities.
• Cellular respiration can release energy from glucose, amino acids, fatty acids and glycerol, but the main food material utilised is glucose
• Cellular respiration


  • Breakdown of glucose to carbon dioxide and water
  • About 60% of available energy released as heat, 40% used to form ATP
• Adenosine triphosphate (ATP)


  • Composed of adenosine + ribose + three phosphate groups
  • High energy chemical bond between 2nd and 3rd phosphate group, when it is broken energy is released.
• Glycolysis


  • Spliting of glucose, does not require oxygen
  • Glucose molecule broken down into two molecules of pyruvate
  • Occurs in cytoplasm
  • First phase in aerobic and anaerobic respiration
• Anaerobic respiration


  • Does not require oxygen
  • Pyruvate produced in glycolysis is converted to lactic acid by fermentation
  • Occurs in cytosol
  • Allows cells to produce some energy without oxygen
  • One glucose molecule can produce two ATP molecules through anaerobic respiration
  • Very important during vigorous physical activity, when the respiratory and circulatory systems are unable to supply muscle cells with enough oxygen to meet all the energy demands of the contracting muscles
• Aerobic respiration


  1. 1 glucose is is broken down into 2 ATP molecules
  2. 2 ATP is converted to 2 Pyruvate.
  3. Pyruvate is converted to acetyl coenzyme A (acetyl CoA). No ATP is produced during this process.
  4. Acetyl CoA then enters the citric acid cycle / Krebs cycle carbon dioxide is a by-product. For every one acetyl CoA that enters the citric acid cycle, one molecule of ATP is also produced. This means that two ATP molecules are produced per glucose molecule.
  5. Electron transport system -> produces 12-17 molecules of ATP per glucose molecule
• Adenosine Diphosphate (ADP)

  • Composed of adenine + ribose + two phosphate groups
• Aerobic Respiration Totals

  • Requires oxygen
  • 1 glucose molecule can produce up to 38 molecules of ATP
  • 2 ATP (glycolysis) + 2 ATP (Citric acid cycle) + 34 (electron transport system)
• Energy use by the cell

  • ATP is used for cell growth, active transport, movement of cell and building complex molecules
  • In cellular respiration, only about 40% of the energy released is incorporated into ATP; the other 60% is lost as heat
• The reactions of cellular respiration are catabolic
• factors affecting enzyme activity

  label:

  A) optimal tempeature

  B) Tempeature

  
• factors affecting enzyme activity

  label:

  A) enzyme concentration