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Metabolism: Fueling Cell Growth - Lecture Slides | BIOL 2111, Study notes of Microbiology

Material Type: Notes; Professor: Xing; Class: Introduction to Microbiology; Subject: Biology; University: Seton Hall University; Term: Fall 2009;

Typology: Study notes

Pre 2010

Uploaded on 11/09/2009

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Metabolism:
Fueling Cell Growth
Chapter 6
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Download Metabolism: Fueling Cell Growth - Lecture Slides | BIOL 2111 and more Study notes Microbiology in PDF only on Docsity!

Metabolism:

Fueling Cell Growth

Chapter 6

Metabolism

  • (^) Cells must accomplish two fundamental tasks

to grow

  • (^) Synthesize new components
    • (^) biosynthesis
  • (^) Harvest energy
  • (^) The sum total of chemical reactions of

biosynthesis and energy-harvesting is termed

metabolism

  • (^) Energy defined as capacity to do work
  • (^) Exists as
    • (^) Potential energy
      • (^) Stored energy
    • (^) Kinetic energy
      • (^) Energy in motion

» Doing work

Harvesting energy

  • (^) Amount of energy available released from bonds is

free energy

  • (^) Energy available to do work
    • (^) If reactants have more free energy than

products, energy is released

  • (^) If products have more energy than reactants,

energy is consumed

Central Metabolic Pathways

  • (^) Pathways modify organic molecules to form
    • (^) High energy intermediates to synthesize ATP
    • (^) Intermediates to generate reducing power
    • (^) Intermediates and end products as precursor metabolites
  • (^) Pathways  (^) Glycolysis  (^) Pentose Phosphate Pathway  (^) Tricarboxylic Acid Cycle

Scheme of Metabolism

Fermentation

  • (^) Used by organisms that cannot respire
    • (^) Due to lack of suitable inorganic electron acceptor or lack of electron transport chain
    • (^) Fermentation stops short of oxidizing glucose or other organic compounds completely, and instead uses an organic intermediate such as pyruvate or a derivative as an electron acceptor
    • (^) Fermentation is partial oxidation of glucose, produces very little ATP; ATP produced only in glycolysis

End products of fermentation pathways E. coli

Chemolithotrophs

  • (^) Chemolithotrophs able to use reduced inorganic chemicals as source of energy
  • (^) These organisms fall into four groups
    • (^) Hydrogen bacteria
      • (^) Oxidize hydrogen gas
    • (^) Sulfur bacteria
      • (^) Oxidize hydrogen sulfide (H 2 S)
    • (^) Iron bacteria
      • (^) Oxidize reduced iron
    • (^) Nitrifying bacteria
      • (^) Two groups
        • (^) One oxidizes ammonia (NH 3 ) to nitrite
        • (^) One oxidizes nitrite (NO 2 −) to nitrate (NO 3 −)
  • (^) Chemolithotrophs generate ATP through oxidative
phosphorylation
  • (^) Organisms thrive in specific environments
    • (^) Particularly where reduced inorganic compounds are found
  • (^) Do not require external carbon source
    • (^) Produce organic carbon from inorganic source through carbon fixation (Carbon dioxide converted to organic carbon)
  • (^) Pigments include
    • (^) Chlorophyll
      • (^) Found in plants, algae and cyanobacteria
    • (^) Bacteriochlorophylls
      • (^) Found in purple and green photosynthetic bacteria
    • (^) Accessory pigments
    • (^) Reaction center pigments
      • (^) Function as electron donors
    • (^) Antennae pigments

Photosynthetic organisms highly visible due

to light capturing pigments

  • (^) Light reactions accomplish two tasks
    • (^) Synthesize ATP through photophosphorylation
    • (^) Generate reducing power to fix carbon dioxide

Anabolic Pathways

  • (^) Synthesis of subunits from precursor metabolites
    • (^) Pathways consume ATP, reducing power and precursor metabolites
    • (^) Make macromolecules once subunits are synthesized
    • (^) Different macromolecules can be joined to form the structures making up the cell
  • (^) Lipid synthesis
  • (^) Amino acid synthesis
  • (^) Nucleotide synthesis

Nucleotides are composed of three units

  1. Nitrogenous base
  • (^) Purine (adenine and guanine) – A, G
  • (^) Pyrimidine (thymine and cytosine) – T, C
  1. 5-carbon sugar molecule (deoxyribose)
  2. Phosphate molecule

Nucleotides bond covalently between the 5’PO 4 of one nucleotide and the 3’OH of another

DNA made up of deoxy-ribo-nucleotides