Download L3_bacterial metabolismCh6HO

Chapter 6: Metabolism
•  The sum total of ALL
chemical reactions
within a cell
–  Catabolic
–  Anabolic
Energy is the capacity to do work
•  Potential energy:
stored energy
•  Kinetic energy: energy
of motion
Organisms obtain energy from
different sources
•  Photosynthetic organisms obtain energy
from…
•  Chemoorganotrophs obtain energy from…..
1
Chemoorganotrophs
depend on
photosynthetic
organisms
Enzymes bind substrate and generate a
product, enzyme is unchanged
Some enzymes require a cofactor to bind
substrate
2
Coenzymes carry electrons
How does this relate to
metabolism?
Factors that influence an enzyme: Temperature
•  What happens as
temperature increases?
•  What is the optimum
temperature?
3
Factors that influence an enzyme: pH
•  What pH do most
enzymes function
optimally?
Enzyme inhibitors
•  Inhibit the binding of the substrate to the
active site
–  Competitive inhibition
–  Non-Competitive Inhibition
Competitive Inhibition
4
Non-competitive Inhibition
Oxidation/reduction reactions
Biological Oxidation
5
ATP is made in catabolic
reactions and used in anabolic
reactions
Ways cells make ATP
•  Substrate level phosphorylation
•  Oxidative phosphorylation
•  Photophosphorylation
Types of Bacterial Metabolism
•  Fermentation
•  Respiration
–  Aerobic Respiration
–  Anaerobic Respiration
•  Photosynthesis
6
Keep in mind…glucose becomes
many different things
Fermentation
•  The incomplete breakdown of glucose with
an organic compound serving as the final
electron acceptor
•  Only pathway operating is glycolysis
7
Fermentation
Lactic Acid Bacteria
Saccharomyces produces ethanol
8
Fermentation products can vary
Aerobic Respiration
•  The COMPLETE breakdown of glucose to
CO2 and H2O with an inorganic compound
serving as the final electron acceptor
Remember the pathways in
aerobic respiration are…
•  Glycolysis
–  Some use Pentose Phosphate Pathway instead
•  TCA cycle
•  Electron transport chain
9
TCA Cycle
What is made as a result of the
TCA cycle?
•  ATP
•  Reducing power
•  Precursor metabolites made from alphaketoglutarate and oxaloacetate
10
Electron Transport Chain
•  Found in the cytoplasmic membrane
•  Contains electron carriers
–  Flavoproteins
–  Iron-sulfur proteins
–  Quinones
–  Cytochromes
Model for energy release in ETC
ETC in eukaryotes
11
ETC in prokaryotes
0
6
2
ATP yield from
aerobic respiration
6
18
4
2
12
Comparison of three types of
metabolism
Remember we are focusing on
catabolic reactions
•  Generate ATP for later use by cell
•  Generate precursors for other pathways
•  Need to re-oxidize coenzymes for continual
use
Precursor metabolites
13