Chapter 2: The Molecules of Life

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Chapter 2The Moleculesof Life
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Important Point
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material Try reading your text before
attending lectures. And take the time to read it
well!
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Weak Bonds Holding Substances Together
Weak Chemical Bonds form the Basis for the
Existence of Life!
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Salt Dissolving in Water
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pH acid lt 7, base gt 7
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pH acid lt 7, base gt 7
To maintain the pH near neutrality, buffers
typically are present in microbial growth media.
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Proteins/Protein Structure
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Proteins/Protein Structure
Proteins only work properly if their primary
structure order of amino acids is correct.
Proteins only work properly if their tertiary (or
quaternary) structures are intact.
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Protein DenaturationDestroys 2, 3, 4
structures
High salt concentrations, detergents, reducing
agents, etc. can also denature proteins.
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Phopholipid Lipid Bilayer
Lipid Bilayer Membranes are held together by weak
intermolecular interactions between
phosopholipids and other molecules including with
proteins.
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Some Relevant Small-Molecules

• In lab well consider small (and some not so
  small) molecules that affect bacterial growth.
• These include (but are not limited to)
• Glucose, Lactose, Sucrose (sugars/carbs)
• Mannitol (alcohol sugar) Starch (both carbs)
• Citrate Malonate (Kreb cycle intermediates)
• Nitrate (alternative final electron acceptor)
• Casein (milk protein) Gelatin (also a protein)
• Amino acids (the units that make up proteins)
• Urea (nitrogenous waste removed by kidneys)
• Other substrates include more complex substances
  such as peptone tryptose (both of which consist
  of partially digested proteins).
• We will also consider a large number of salts,
  indicators (including pH indicators), pH buffers,
  metabolic products, inhibitors of bacterial
  growth.

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