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Microbial Metabolism

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Microbial Metabolism Chapter 5 – PowerPoint PPT presentation

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Title: Microbial Metabolism


1
Microbial Metabolism
  • Chapter 5

2
Metabolism - all of the chemical reactions within
a living organism
  • 1. Catabolism ( Catabolic )
  • breakdown of complex organic molecules into
    simpler compounds
  • releases ENERGY
  • 2. Anabolism ( Anabolic )
  • the building of complex organic molecules from
    simpler ones
  • requires ENERGY

3
Enzymes - catalysts that speed up and direct
chemical reactions
  • A. Enzymes are substrate specific
  • Lipases Lipids
  • Sucrases Sucrose
  • Ureases Urea
  • Proteases Proteins
  • DNases DNA

4
Enzyme Specificity can be explained by the Lock
and Key Theory
E S -----gt ES ------gt E P
5
Naming of Enzymes - most are named by adding
ase to the substrate
  • Sucrose Sucrase
  • Lipids Lipase
  • DNA DNase
  • Proteins Protease
  • removes a Hydrogen Dehydrogenase
  • removes a phosphate phosphotase

6
Naming of Enzymes
  • Grouped based on type of reaction they catalyze
  • 1. Oxidoreductases oxidation reduction
  • 2. Hydrolases hydrolysis
  • 3. Ligases synthesis

7
Enzyme Components 2 Parts 1. Apoenzyme -
protein portion 2. Coenzyme (cofactor) -
non-protein
Holoenzyme - whole enzyme
8
Coenzymes
  • Many are derived from vitamins
  • 1. Niacin
  • NAD (Nicotinamide adenine dinucleotide)
  • 2. Riboflavin
  • FAD (Flavin adenine dinucleotide)
  • 3. Pantothenic Acid
  • CoEnzyme A

9
Factors that Influence Enzymatic Activity
Denaturation of an Active Protein
10
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13
Inhibitors can effect enzymatic activity 1.
Competitive Inhibitors 2. Noncompetitive
Inhibitors
14
Competitive Inhibitors -compete for the active
site
  • 1. Penicillin
  • competes for the active site on the enzyme
    involved in the synthesis of the pentaglycine
    crossbridge
  • 2. Sulfanilamide (Sulfa Drugs)
  • competes for the active site on the enzyme that
    converts PABA into Folic Acid
  • Folic Acid - required for the synthesis of DNA
    and RNA

Selective Toxicity
15
Non-competitive Inhibitors - attach to an
allosteric site
16
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17
Energy Production
  • 1. Oxidation
  • refers to the loss of Hydrogens and or electrons
  • 2. Reduction
  • the gain of Hydrogens and or electrons

NAD Cycle
18
Carbohydrate Catabolism
  • Microorganisms oxidize carbohydrates as their
    primary source of energy
  • Glucose - most common energy source
  • Energy obtained from Glucose by
  • Respiration
  • Fermentation

19
Aerobic Cellular Respiration
  • Electrons released by oxidation are passed down
    an Electron Transport System with oxygen being
    the Final Electron Acceptor
  • General Equation
  • Glucose oxygen----gt Carbon dioxide water
  • ATP

20
Chemical Equation
  • C6H12O6 6 O2 -------gt 6 CO2 6 H2O
  • 38 ADP 38 P 38 ATP

21
Aerobic Cellular Respiration
  • 4 subpathways
  • 1. Glycolysis
  • 2. Transition Reaction
  • 3. Krebs Cycle
  • 4. Electron Transport System

22
1. Glycolysis (splitting of sugar)
  • Oxidation of Glucose into 2 molecules of Pyruvic
    acid
  • Embden-Meyerhof Pathway
  • End Products of Glycolysis
  • 2 Pyruvic acid
  • 2 NADH2
  • 2 ATP

23
2. Transition Reaction
  • Connects Glycolysis to Krebs Cycle
  • End Products
  • 2 Acetyl CoEnzyme A
  • 2 CO2
  • 2 NADH2

24
3. Krebs Cycle (Citric Acid Cycle)
  • Series of chemical reactions that begin and end
    with citric acid
  • Products
  • 2 ATP
  • 6 NADH2
  • 2 FADH2
  • 4 CO2

25
4. Electron Transport System
  • Occurs within the cell membrane of Bacteria
  • Chemiosomotic Model of Mitchell
  • 34 ATP

26
How 34 ATP from E.T.S. ?3 ATP for each NADH22
ATP for each FADH2
  • NADH2
  • Glycolysis 2
  • T. R. 2
  • Krebs Cycle 6
  • Total 10
  • 10 x 3 30 ATP
  • FADH2
  • Glycolysis 0
  • T.R. 0
  • Krebs Cycle 2
  • Total 2
  • 2 x 2 4 ATP

27
Total ATP production for the complete oxidation
of 1 molecule of glucose in Aerobic Respiration
  • ATP
  • Glycolysis 2
  • Transition Reaction 0
  • Krebs Cycle 2
  • E.T.S. 34
  • Total 38 ATP

28
Anaerobic Respiration
  • Electrons released by oxidation are passed down
    an E.T.S., but oxygen is not the final electron
    acceptor
  • Nitrate (NO3-) ----gt Nitrite (NO2-)
  • Sulfate (SO24-) ----gt Hydrogen Sulfide
    (H2S)
  • Carbonate (CO24-) -----gt Methane (CH4)

29
Fermentation
  • Anaerobic process that does not use the E.T.S.
    Usually involves the incomplete oxidation of a
    carbohydrate which then becomes the final
    electron acceptor.
  • Glycolysis - plus an additional step

30
Fermentation may result in numerous end products
1. Type of organism 2. Original substrate 3.
Enzymes that are present and active
31
1. Lactic Acid Fermenation
  • Only 2 ATP
  • End Product - Lactic Acid
  • Food Spoilage
  • Food Production
  • Yogurt - Milk
  • Pickles - Cucumbers
  • Sauerkraut - Cabbage
  • 2 Genera
  • Streptococcus
  • Lactobacillus

32
2. Alcohol Fermentation
  • Only 2 ATP
  • End products
  • alcohol
  • CO2
  • Alcoholic Beverages
  • Bread dough to rise
  • Saccharomyces cerevisiae (Yeast)

33
3. Mixed - Acid Fermentation
  • Only 2 ATP
  • End products - FALSE
  • Escherichia coli and other enterics

34
Propionic Acid Fermentation
  • Only 2 ATP
  • End Products
  • Propionic acid
  • CO2
  • Propionibacterium sp.

35
Fermentation End Products
36
Lipid Catabolism
37
Protein Catabolism
38
Photosynthesis - conversion of light energy from
the sun into chemical energy
  • Chemical energy is used to reduce CO2 to sugar
    (CH2O)
  • Carbon Fixation - recycling of carbon in the
    environment (Life as we known is dependant on
    this)
  • Photosynthesis
  • Green Plants
  • Algae
  • Cyanobacteria

39
Chemical Equation
  • 6 CO2 6 H2O sunlight -----gt C6H12O6 6
    O2
  • 2 Parts
  • 1. Light Reaction
  • 2. Dark Reaction

40
Light Reaction
  • Non-Cyclic Photophosphorylation
  • O2
  • ATP
  • NADPH2
  • Light Reaction (simplified)

41
2. Dark Reaction
42
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