Transcript Bacterial Classification

Bacterial Metabolism
Introduction
Enzymes
Energy Production
Bacterial Catabolism
Bacterial Metabolism
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Introduction
– Metabolism - sum of all chemical reactions
in cell
– Anabolism - reactions that synthesize or
“build up” e.g. protein synthesis
– Catabolism - reactions that digest or “break
down” e.g. starch to glucose
Bacterial Metabolism
Enzyme Introduction
 Enzyme Components
 Enzyme Mechanism
 Factors Influencing Enzymes
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Bacterial Metabolism
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Enzyme Introduction
– Enzymes are biological catalysts
– Catalysts are agents which speed up a
reaction
– Enzymes are very specific
– Enzymes are typically proteins
– Catalysts work by lowering the activation
energy of a reaction
Bacterial Metabolism
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Enzymes work to
lower activation
energy
Bacterial Metabolism
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Enzyme Components
– Cofactor - nonprotein component that is
part of enzyme, e.g. Fe, NAD+, biotin
– Apoenzyme - protein portion of enzyme
– Holoenzyme - Cofactor plus apoenzyme
Bacterial Metabolism
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How enzymes speed up reactions
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Proximity
Orientation
Induced fit
Reactive groups
Cofactors
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Enzyme Mechanism
– Substrate binds to active site; lock & key
specificity; induced fit
– Formation of enzyme-substrate complex
– Catalytic activity; localized acid or base or
induced fit
Bacterial Metabolism
Bacterial Metabolism
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Factors Influencing Enzymes
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Temperature
pH
Salt concentration
Inhibitors
» Competitive (active site)
» Non - Competitive (allosteric)
– Feedback Inhibition
Bacterial Metabolism
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Energy Production
– Oxidation / Reduction reactions
– Role of ATP
– Phosphorylation
» Substrate
» Oxidative
» Photo-
Bacterial Metabolism
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Oxidation / Reduction
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Oxidation - loss of electrons
Reduction - gain of electrons
Redox reactions always coupled
Oxidation of reduced carbon tends to be
energetically favorable
Bacterial Metabolism
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Carbon Oxidation/Reduction
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Carbon Dioxide CO2
Acid (Formic Acid HCO2)
Aldehyde (Formaldehyde - H2CO)
Alcohol (Methanol - H3COH)
Methane CH4
(+4)
(+2)
(0)
(-2)
(-4)
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Oxidation States
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Alcohols
Fats
Organic Acids (acetic acid)
Glucose
Bacterial Metabolism
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Role of ATP
– ATP  ADP + Pi
– Energy intermediate or “currency”
– Hydrolysis of ATP “coupled” to
energetically unfavorable reactions
Bacterial Metabolism
Bacterial Metabolism
Glucose + Pi  Glucose-6-PO4 + H2O
ΔG = +13.8 kJ/mol, Keq = 5 x 10-3
 ATP + H20  ADP + Pi
ΔG = -30.5 kJ/mol, Keq = 4 x 105
 Glucose + ATP  Glucose-6-PO4 + ADP
ΔG = (-30.5 kJ/mol) + (+13.8 kJ/mol)
= -16.7 kJ/mol
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Bacterial Metabolism
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Phosphorylation
– Substrate - direct transfer of phosphate
from an organic molecule to ADP
– Oxidative - ATP generated via
chemiosmosis (“proton pump”) and ATP
synthase
– Photo - light energy from photosynthesis, a
modification of chemiosmosis
Bacterial Metabolism
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Bacterial Catabolism
– Carbohydrate catabolism has two
functions:
» energy production and/or storage
» generation of chemical intermediates
– Cellular respiration and fermentation
– Includes three processes:
» Glycolysis
» Kreb’s or Tricarboxylic Acid (TCA) cycle
» Electron transport /oxidative phosphorylation