Bacterial Metabolism

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• Bacterial Metabolism
• I. Enzymes
• A. Importance of Enzymes
• 1. Catalyze chemical reactions
• 2. Enzymes can be toxins.
• B. Structure
• 1. Enzymes are protein molecules
• a. Protein structure levels
• - Primary Structure
• Sequence of amino acids on the
  chain.

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• Secondary Structure
• Long chain of amino acids twist on itself.
• Coiling held by hydrogen bonds (weak
  bonds).
• Tertiary Structure
• Three dimensional globular shape held by
• strong bonds. Form active sites.

Active site
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Quaternary Structure 2 or more globular
chains attach to one another.

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• How do Enzymes work?

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• Enzyme changes the substrate into a product.
• Digestion reaction break down
• Synthesis reaction builds up
• D. Properties of Enzymes
• 1. Specific
• 2. Reusable
• 3. Named by type of substrate or reaction
• ASE (suffix added to the root word)
• Urease, Lipase, DNA-ase, etc.

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• 4. Classes of Enzymes
• Exoenzymes (extracellular target)
• endoenzymes (Intracellular target).
• II. Energy From Food
• Once food molecules are inside cell, how
• does the cell remove energy?
• A. Chemical Energy
• Food molecules have many chemical
  bonds
• that can be broken and the energy
  utilized for
• cell metabolic needs.

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• Basic Concepts in Bio- Chemistry
• ____________________________
• Electrons and Carriers
• - Oxidation the removal of electrons and
• Hydrogens.
• - Reduction the addition of electrons and
• Hydrogens.
• - coupled reactions

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• Adenosine Triphosphate ATP
• - energy storing molecule.
• - molecule has many high energy bonds.
• - cell currency .
• How does it happen?
• B. Oxidation
• - removal of electrons from elements or
  
• compounds and general process to
  break
• down food chemical bonds.
• 1. Inorganic molecules
• 2. Organic molecules

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• 1. Inorganic foods
• Fe Fe
  e-

Iron II oxidation Iron III electron
Oxygen oxidizes the Iron (gain or receive the
electrons)in turn it gets reduced.

• Organic foods
• In most biological oxidations, one electron
  is removed along with a Hydrogen atom
  Dehydrogenation Reaction.

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• Electrons and Hydrogens are removed from one
  molecule and transferred by a Carrier molecule
  called a Co-enzyme.
• NAD Nicotinamide Adenine Dinucleotide
• - It can carry 2 hydrogens at a
  time
• for each electron transferred.
• NAD 2H e- NADH2 e-
• - It will deliver the
  electrons along with the
• Hydrogens to an acceptor.

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• Glucose molecule many chemical bonds can
  release
• a great deal of energy. Each time one bond
  is broken, electrons (along with Hydrogens) are
  removed and so is energy. Every time a compound
  is oxidized, energy is released.

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• C. General Pathways to break down
• food molecules
• 1. Aerobic Respiration
• 2. Anaerobic Respiration
• 1. Aerobic Respiration food is oxidized
• completely to CO2. Oxygen is required
  as
• a final electron acceptor
  (hydrogens).
• C6H12O6 CO2 H2O
• Glucose Carbon dioxide Water

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• 2. Anaerobic Fermentation
• - Food not oxidized completely.
• - No Oxygen needed.
• - Lacks a functional electron
  transport chain.
• - Uses only Glycolysis to break down
• glucose to pyruvic acid.
• - Net 2 ATPs (substrate level)
• - Most energy remains in
  fermentation
• products.

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• C6H12O6 2(C3H4O3) 2NAD-H2 2ATP

Glycolysis
Krebss cyc l e
ETS electron transport
system
ATP
ATP
H2 O H2O 6ATP
ATP
3 ATPs per H pair(H2)
6 CO2 10H2 2 ATP
8H2 -NAD24 ATP 2H2 -FAD 4 ATP
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• Final Reaction
• C6H12O6 6O2 6CO2 6H2O 38
  ATP
• ATP count
• 1. Glycolysis 2
  ATP
• 2. Krebss cycle 2
  ATP
• 3. ETS
• (6ATP from Glycolysis NAD) 6
  ATP
• (24 ATP from 8H2 Krebss NAD) 24 ATP
• (4 ATP from 2H2 Krebss FAD) 4 ATP
• 
  ____________
• 
  Total 38 ATP

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• Products of Anaerobic fermentation
• ________________________
• Organic acidsLactic acid, Acetic acid,etc.
  
• Alcohols Ethanol, etc.
• Gases Methane, etc.
• Net energy 2 ATPs (Glycolysis)

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