Transcript Matrix: Citric Acid Cycle and Pyruvate Oxidation Mitochondrion A

Cellular Respiration
Part 2
Producing ATP by Oxidative
Phosphorylation
Energy from Macromolecules
Releasing Energy From Glucose
Glucose (6C)
Glycolysis
Energy
Released
ATP
e- Carriers
2 X Pyruvate (3C)
Cytoplasm
O2 present
2 CO2
Energy
Released
Mitochondrion
e- Carriers
2 X Acetyl-CoA (2C)
e-
eATP
e-
Citric Acid
Cycle
4 CO2
e- Carriers
ATP
H2O
2 H+
½ O2
Locations of Cellular Respiration Components
a
Mitochondrion
b
Outer
Membrane
A Crista
Inner
Membrane:
Has ATP Synthase
Electron Transport Chain
Intermembrane
Compartment
H+ accumulates
Matrix: Citric Acid Cycle
and Pyruvate Oxidation
Sequence of
Electron Carriers
FADH2 donates
electrons to
Complex II
(Succinate
Dehydrogenase)
NADH donates
electrons to
Complex I
(NADH
Dehydrogenase)
The poison
cyanide prevents
transfer of
electrons to
oxygen
Cytochromes
are electron
carriers with a
heme prosthetic
group
Protons are
pumped from the
matrix into the
intermembrane
space
Formation of
H+ Gradient
Flow of protons
through ATP
synthase powers
ATP production
The poison
arsenic prevents
the buildup of the
H+ gradient
The inner
mitochondrial
membrane is
impermeable to
H+, which can
only pass through
the ATP synthase
ATP Synthase
H+ ions cause the
rotor of ATP
synthase to spin
The internal rod
also spins as a
result of rotor
movement
Sites in the catalytic
knob are activated to
catalyze ATP
production
Oxidative Phosphorylation
• Production of ATP as a result of electron transfer
through carriers in the Electron Transport Chain
– Electrons pass through a set of membrane-associated
carriers by a series of redox reactions
– Energy from electron transport powers the active
transport of H+ to the intermembrane compartment of the
mitochondrion, building a concentration gradient
– Chemiosmosis: Diffusion of hydrogen ions (H+) through
the differentially permeable inner mitochondrial
membrane, resulting in ATP production
• H+ can only cross the membrane into the mitochondrial
matrix through the pores of an ATP-synthesizing enzyme
• Movement of H+ through the enzyme provides energy for
ATP synthesis
Fermentation
oxidized e- Carriers
Glucose (6C)
Glycolysis
Fermentation
2 X Pyruvate (3C)
X 2 CO
O2 present
Cytoplasm
ATP
e- Carriers
(in muscle)
O2 absent
2
2 X Lactate (3C)
e- Carriers
when O2 becomes available
2 X Acetyl-CoA (2C)
Mitochondrion
Citric Acid
Cycle
4 CO2
e- Carriers
ATP
Alcoholic
Fermentation
Alcoholic and Lactic Acid
Fermentation
Lactic Acid
Fermentation
Yeasts
Some Plants
Muscle cells
Microorganisms
Energy From Macromolecules
Glucose (6C)
Gluconeogenesis
Polysaccharides
Glycolysis
2 X Pyruvate (3C)
Monosaccharides
Disaccharides
2 X Acetyl-CoA (2C)
Citric Acid
Cycle
Energy From Macromolecules
Glucose (6C)
Gluconeogenesis
Triglycerides
DAP
Glycolysis
2 X Pyruvate (3C)
2 X Acetyl-CoA (2C)
Citric Acid
Cycle
Glycerol
Fatty Acids
(~5%) multiples of 2C
Energy From Macromolecules
Glucose (6C)
Gluconeogenesis
Glycolysis
2 X Pyruvate (3C)
2 X Acetyl-CoA (2C)
Citric Acid
Cycle
Proteins
3C-amino Other amino
acids
Acids
Anabolic Interconversions
Glucose (6C)
Gluconeogenesis
Glycolysis
Polysaccharides
Glycerol
2 X Pyruvate (3C)
Triglycerides
2 X Acetyl-CoA (2C)
Citric Acid
Cycle
Fatty Acids
Amino Acids
Proteins
Regulation of
Glycolysis
• Phosphofructokinase is
– allosterically inhibited
by ATP
– allosterically activated
by ADP or AMP
– inhibited by citrate
Regulation of the Citric Acid Cycle
• Isocitrate dehydrogenase
– responds to negative
feedback from NADH
and H+ and ATP
– is activated by ADP and
NAD+
Regulation of
Acetyl-CoA
• Entering the Citric Acid
Cycle
– Citrate synthase (1)
is inhibited by ATP
or NADH
• Use in Fatty Acid
Synthesis
– Fatty Acid synthase (2)
is stimulated by Citrate
(2)
(1)