Intermediary Metabolism
Living organisms require continual energy
expenditure for maintenance of structure & function
Production of chemical energy often is from
complete oxidation of complex molecules to:
CO2, H2O and small N-containing
compounds (e.g. urea)
Summary of Glucose Breakdown
C6H12O6 + 6O2
6H2O + 6CO2 +
Energy (as ATP)
Most energy is captured in the form of ATP:
from Lodish et al., Molecular Cell Biology 3.0
Why is Glucose the Primary Fuel?
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It is a relative stable compound
It is a relatively reduced compound
It is readily soluble in water
Its degradation provides a skeleton for
entering metabolic pathway at several
points
Mitochondrion
Glycolysis
6 NAD+
2 FAD
Glucose
2 NAD+
2 ADP
2 ATP
2 NADH
2 NAD+
FP
2 NADH
2 NAD+
2 acetylCoA
2 NADH
ADP
ATP
2 Pyruvate
3H+
2 GDP
TCA
Cycle
½O2
2 GTP
6 NADH
2 FADH2
2H+ 2H+ 2H+ 4H+
from Lodish et al., Molecular Cell Biology 3.0
from Lodish et al., Molecular Cell Biology 3.0
Electron Transport System
ATP Balance Sheet
Glycolysis (Anaerobic)
=
2 ATP
Kreb’s Cycle/Citric Acid Cycle = 30 ATP
Redox Reaction in Glycolysis = ______
6 ATP
Total = 38 ATP
During functional or environmental
anaerobiosis:
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Electron transport ceases
Reducing equivalents build up
TCA Cycle no longer functional
Can’t use fats or proteins to make ATP
Even glycolysis is limited by lack of NAD+
We’ll first look at mechanisms
to insure delivery of O2
Then, we’ll look at the biochemical
adaptations necessary to continue
glycolysis under conditions of
hypoxia and anoxia