Download L4_bacterial metabolism7e

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…..
Chemoorganotrophs
depend on
photosynthetic
organisms
Let’s focus on metabolism of
chemoorganotrophs (bacteria)
• Where do they obtain carbon?
• How do they generate energy?
What promotes chemical
reactions in biological systems?
What promotes chemical
reactions in biological systems?
ENZYMES
Enzymes bind substrate and generate a
product, enzyme is unchanged
Some enzymes require a cofactor to bind
substrate
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?
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
Non-competitive Inhibition
Oxidation/reduction reactions
Biological Oxidation
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
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
Fermentation
Lactic Acid Bacteria
Saccharomyces produces ethanol
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
What is made as a result of the
TCA cycle?
• ATP
• Reducing power
• Precursor metabolites made from alphaketoglutarate and oxaloacetate
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
ETC in prokaryotes
ATP yield from aerobic respiration
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