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Microbial Metabolism

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Microbial Metabolism Pathway By substrate-level phosphorylation By oxidative phosphorylation From NADH From FADH Glycolysis 2 6 0 Intermediate step 0 6 Krebs cycle 2 ... – PowerPoint PPT presentation

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Title: Microbial Metabolism


1
Microbial Metabolism
2
What is metabolism?
  • All chemical reactions/activities in cell
  • Catabolism
  • Hydrolysis
  • Use energy to make ATP
  • ADP Pi energy ? ATP
  • Anabolism
  • Dehydration synthesis
  • Need energy for reaction
  • ATP ? ADP Pi energy
  • Enzymes frequently catalyze reactions
  • Oxidation/reduction

3
What is the difference between
  • Hydrolysis
  • Condensation (dehydration synthesis)
  • Exergonic vs. endergonic

4
What are enzymes?
  • Without enzymes, collision theory rules
  • Need sufficient activation energy
  • Number of molecules above this activation level
    reaction rate
  • Enzymes are molecules that lower the
    ______________
  • Catalysts
  • Work on substrate

5
What does the enzyme work on?
  • Substrate
  • Molecules which are changed during reaction
  • Enzyme-substrate complex forms temporarily
  • Lock and key model
  • Highly specific fit
  • End in -ase
  • Turnover number
  • Number of molecules enzyme converts per second
  • DNA polymerase 15 lactate dehydrogenase 1,000

6
What are the parts of an enzyme?
  • Some are only a polypeptide chain
  • Most have two parts
  • Apoenzyme (polypeptide chain)
  • Cofactor (inorganic) or coenzyme (organic)
  • NAD (nicotinamide adenine dinucleotide) us.
    catabolic
  • NADP (nicotinamide adenine dinucleotide
    phosphate) us. anabolic
  • Coenzyme A (CoA)pantothenic derivitive (another
    B vitamin)
  • Others are metals Cu, Mg, Mn, Zn, Ca, Co
  • Together these form holoenzyme

From niacin
7
How does an enzyme work?
  • Enzymes controlled by
  • Enzyme synthesis
  • How much is made
  • Hormones can influence (e.g. TH)
  • Enzyme activity
  • Temperature influences
  • Denaturation
  • pH influences
  • Substrate concentration influences
  • Saturation point

8
How does an enzyme work?
  • Inhibitors influence
  • Competitive
  • Fill active site sulfanilamide vs
    para-aminobenzoic acid (PABA)
  • Non-competitive
  • Allosteric inhibition

9
Factors Influencing Enzyme Activity
  • Enzymes can be denatured by temperature and pH

Figure 5.6
10
Factors Influencing Enzyme Activity
  • Temperature
  • pH
  • Substrate concentration

Figure 5.5a
11
Factors Influencing Enzyme Activity
  • Competitive inhibition

Figure 5.7ab
12
Factors influencing enzyme activity
  • Feedback inhibition

Figure 5.8
13
Cell Energetics
14
Oxidation-Reduction
  • Oxidation is the removal of electrons.
  • Reduction is the gain of electrons.
  • Redox reaction is an oxidation reaction paired
    with a reduction reaction.

Figure 5.9
15
Oxidation-Reduction
  • In biological systems, the electrons are often
    associated with hydrogen atoms. Biological
    oxidations are often dehydrogenations.

Figure 5.10
16
What happens in carbohydrate catabolism?
  • Glucose usually is substrate
  • Glycolysis
  • 2 ATP
  • Followed by either
  • Aerobic respiration
  • ___ ATP
  • Anaerobic fermentation
  • No more ATP

17
What is ATP?
  • Adenosine triphosphate
  • Made by phosphorylating ______
  • Equation

18
What is glycolysis?
  • First step to making TP from glucose
  • Convert glucose to _____________
  • Some bacteria can breakdown other molecules
  • Pentose phosphate pathway (pentoses)
  • E. coli, Bacillus subtilis

19
What happens next?
  • If oxygen present ?
  • No oxygen ?

20
Preparatory Stage
  • Two ATPs are used
  • Glucose is split to form two Glucose-3-phosphate

1
3
4
5
Figure 5.12, step 1
21
Energy-Conserving Stage
  • Two Glucose-3-phosphate oxidized to two Pyruvic
    acid
  • Four ATP produced
  • Two NADH produced

9
Figure 5.12, step 2
22
Intermediate Step
  • Pyruvic acid (from glycolysis) is oxidized and
    decarboyxlated.

Figure 5.13 (1 of 2)
23
What is the Krebs Cycle?
  • AKA citric acid cycle
  • Acetyl CoA (2 carbons) releases energy
  • Produces ATP, CO2, NADH, FADH2
  • NADH and FADH2 to Electron transport chain (ETC)

24
What are some intermediates in the Krebs cycle?
  • Some drugs are metabolized similar to these
  • citric acid (6 carbons)
  • iso-citric acid (6)
  • alpha-ketoglutaric acid (5)
  • succinyl CoA (4)
  • succinic acid (4)
  • fumaric acid (4)
  • malic acid (4)
  • oxaloacetic acid (4)
  • Krebs cycle animation

25
What is the electron transport chain?
  • Carrier molecules facilitate oxidation and
    reduction
  • Oxidation loss of electron
  • Reduction gain of electron
  • Transfer electrons from higher to lower energy
    compounds
  • Chemiosmosis w/ oxidative phosphorylation
  • Prokaryotes PM
  • Eukaryotes mitochondrial crista
  • Disruption of ETC leads to death!
  • Cyanide
  • First ETC animation
  • Second ETC animation

26
What is the sum reaction for aerobic respiration?
  • Glucose 6 H2O 38 ADP 38 Pi ?
  • 6 CO2 6 H2O 38 ATP

27
What happens in anaerobic respiration?
  • Final electron acceptor is not oxygen
  • Various amounts of ATP produced
  • Slower and less ATP than aerobic respiration
  • Uses some parts of Krebs cycle
  • Thus slower growth for anaerobes than aerobes

28
What is fermentation?
  • Pyruvic acid from glycolysis
  • Converted to end-products
  • If bacteria only produce lactic acid homolactic
  • No additional ATP

29
What is alcohol fermentation?
  • Also happens after glycolysis
  • Produces ethanol and CO2
  • Heterolactic produces lactic acid other acids,
    alcohols

30
What happens in lipid protein catabolism?
  • Some bacteria dont like carbs!
  • Lipases break down ______
  • Krebs cycle oxidizes products
  • Useful for oil spill clean up
  • Extracellular proteases peptidases break down
    _______
  • Deamination converts amino acids to usable form
    for Krebs cycle
  • By production is ammonia

31
Anaerobic Respiration
Electron acceptor Products
NO3 NO2, N2 H2O
SO4 H2S H2O
CO32 CH4 H2O
32
Pathway Eukaryote Prokaryote
Glycolysis Cytoplasm Cytoplasm
Intermediate step Cytoplasm Cytoplasm
Krebs cycle Mitochondrial matrix Cytoplasm
ETC Mitochondrial inner membrane Plasma membrane
33
  • Energy produced from complete oxidation of one
    glucose using aerobic respiration.

Pathway ATP produced NADH produced FADH2 produced
Glycolysis 2 2 0
Intermediate step 0 2
Krebs cycle 2 6 2
Total 4 10 2
34
  • ATP produced from complete oxidation of one
    glucose using aerobic respiration.

Pathway By substrate-level phosphorylation By oxidative phosphorylation By oxidative phosphorylation
Pathway By substrate-level phosphorylation From NADH From FADH
Glycolysis 2 6 0
Intermediate step 0 6
Krebs cycle 2 18 4
Total 4 30 4
36 ATPs are produced in eukaryotes.
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