BIOENERGY

• Metabolism


  Sum total of all chemical reactions in a living organism
• Catabolism


  All metabolic reactions in which large biochemical molecules are broken down to smaller ones
• Anabolism


  All metabolic reactions in which small biochemical molecules are joined to form larger ones
• Metabolic Pathway


  Series of consecutive biochemical reactions used to convert a starting material into an end product
• Types of metabolic pathways

  • Linear
  • Cyclic
• Protein synthesis


  1. Amino acids

  2. Protein
• Triacylglycerol formation


  1. Glycerol

  2. Fatty acids

  3. Triacylglycerol
• Polysaccharide hydrolysis


  1. Polysaccharide

  2. Monosaccharides
• Nucleic acid formation


  1. Nucleotides

  2. Nucleic acid
• Prokaryotic cell


  Single compartment organism, no nucleus, single circular DNA molecule
• Eukaryotic cell


  Multi-compartment cell, DNA in membrane-enclosed nucleus, larger than bacterial cells
• Eukaryotic cell organelles and their functions

  • Nucleus: DNA replication and RNA synthesis
  • Plasma membrane: Cellular boundary
  • Cytoplasm: Water-based material
  • Mitochondria: Generate energy
  • Lysosome: Cell rebuilding, repair and degradation
  • Ribosome: Protein synthesis
• Mitochondria


  Outer membrane: Permeable to small molecules, Inner membrane: Highly impermeable, Site of ATP synthesis
• Adenosine phosphates


  AMP: One phosphate group, ADP: Two phosphate groups, ATP: Three phosphate groups, cAMP: Cyclic structure
• AMP


  Structural component of RNA
• ADP and ATP


  Key components of metabolic pathways, Phosphate groups connected by strained bonds
• ATP hydrolysis


  1. ATP + H2O -> ADP + PO4^3- + Energy

  2. ADP + H2O -> AMP + PO4^3- + Energy

  3. ATP + 2H2O -> AMP + 2PO4^3- + Energy
• ATP function


  Source of phosphate group and source of energy
• Other nucleotide triphosphates


  • UTP: Carbohydrate metabolism
  • GTP: Protein and carbohydrate metabolism
  • CTP: Lipid metabolism
• Flavin Adenine Dinucleotide (FAD)


  Coenzyme required in redox reactions, Flavin subunit is active form
• FAD redox reaction


  Conversion of alkane to alkene
• NAD+


  Coenzyme, NADH is reduced form
• NAD+ redox reaction


  Oxidation of secondary alcohol to ketone
• Coenzyme A


  Derivative of vitamin B, Active form is sulfhydryl group
• Acetyl-CoA


  Acetylated form of coenzyme A
• Classification of metabolic intermediate compounds

  • High-energy phosphate compounds
  • Coenzymes
  • Regulatory compounds
• High-energy phosphate compounds


  Contain strained bonds, greater free energy of hydrolysis than normal compounds
• Free energies of hydrolysis of common phosphate-containing metabolic compounds
• Biochemical energy production


  1. Digestion

  2. Acetyl group formation

  3. Citric acid cycle

  4. Electron transport chain and oxidative phosphorylation
• Digestion


  Breakdown of food into small molecules that can be absorbed into the blood
• Acetyl group formation


  Oxidation of small molecules to produce acetyl CoA
• Citric acid cycle


  Oxidation of acetyl group to CO2, production of NADH and FADH2
• Electron transport chain and oxidative phosphorylation

  Oxidation of NADH and FADH2 to produce ATP
• Citric acid cycle


  1. Formation of citrate

  2. Subsequent reactions
• Citric acid cycle


  A series of biochemical reactions in which the acetyl portion of acetyl CoA is oxidized to carbon dioxide and the reduced coenzymes FADH2 and NADH are produced
• Tricarboxylic acid cycle (TCA) or Krebs cycle


  Also known as the citric acid cycle
• Citric acid cycle


  • Citric acid is a tricarboxylic acid
  • Named after Hans Krebs who elucidated this pathway
• Two important types of reactions in the citric acid cycle

  • Oxidation of NAD+ and FAD to produce NADH and FADH2
  • Decarboxylation of citric acid to produce carbon dioxide
• Citric acid cycle reactions

  1. Acetyl CoA + 3NAD+ + FAD + GDP + Pi + 2H2O

  2. 2CO2 + CoA-SH + 3NADH + 2H+ + FADH2 + GTP
• Steps of the citric acid cycle

  1. Step 1: Formation of Citrate

  2. Step 2: Formation of Isocitrate

  3. Step 3: Oxidation of Isocitrate and Formation of CO2

  4. Step 4: Oxidation of Alpha-Ketoglutarate and Formation of CO2

  5. Step 5: Thioester bond cleavage in Succinyl CoA and Phosphorylation of GDP

  6. Step 6: Oxidation of Succinate

  7. Step 7: Hydration of Fumarate

  8. Step 8: Oxidation of L-Malate to Regenerate Oxaloacetate