Transcript NADH - Cloudfront.net

Aerobic
Respiration
Section
9:2
Overview
 Krebs
Cycle: the oxidation of
glucose and the reduction of
NAD+ to NADH.
 Electron Transport Chain:
where NADH is used to make
ATP.
 Krebs or the ETC. will not occur
unless, CO2, H2O and O2 are
ALL present.
Aerobic Respiration – Oxygen
Present
 Occurs
in the mitochondria of
eukaryotes and the cytosol of
prokaryotes
 Pyruvic acid from glycolysis diffuses
in from the cytosol to the mitochondrial
matrix
 The space inside the inner
membranes
inner compartment
outer compartment
cytoplasm
outer
mitochondrial
membrane
inner
mitochondrial
membrane
(see next slide)
Fig. 7.5a, p. 114
Aerobic Respiration
Pyruvic
acid joins with
coenzyme A (CoA) to form
acetyl CoA – 2 carbons
CO2 is lost in this process
and NAD is reduced to
NADH and H+.
Krebs Cycle
A biochemical pathway that
breaks down acetyl CoA
producing CO2, hydrogen, and
ATP.
 5 steps to the Krebs cycle
Step 1
 The 2-carbon acetyl CoA
combines with a 4-carbon
compound, oxaloacetic acid,
to form a 6-carbon molecule,
citric acid
 This step regenerates
coenzyme A
PREPARATORY
STEPS
pyruvate
coenzyme A (CoA)
NAD+
(CO2)
NADH
CoA
Acetyl–CoA
KREBS CYCLE
CoA
oxaloacetate
citrate H O
2
NADH
H2O
NAD+
malate
NAD+
H2O
isocitrate
NADH
fumarate
FADH2
FAD
a-ketogluterate
CoA
NAD+
NADH
succinate
CoA
succinyl–CoA
ATP
ADP + phosphate
group (from GTP)
Fig. 7.6, p. 115
Step 2
 Citric
acid releases a CO2
and a hydrogen to form a 5carbon compound
 NAD+ accepts an H+ to
+
become NADH and H .
PREPARATORY
STEPS
pyruvate
coenzyme A (CoA)
NAD+
(CO2)
NADH
CoA
Acetyl–CoA
KREBS CYCLE
CoA
oxaloacetate
citrate H O
2
NADH
H2O
NAD+
malate
NAD+
H2O
isocitrate
NADH
fumarate
FADH2
FAD
a-ketogluterate
CoA
NAD+
NADH
succinate
CoA
succinyl–CoA
ATP
ADP + phosphate
group (from GTP)
Fig. 7.6, p. 115
Step 3
 The
5-carbon compound
releases CO2 and H+ to form a
4-carbon compound.
 NAD+ is reduced again to
NADH and One molecules of
ATP is made
PREPARATORY
STEPS
pyruvate
coenzyme A (CoA)
NAD+
(CO2)
NADH
CoA
Acetyl–CoA
KREBS CYCLE
CoA
oxaloacetate
citrate H O
2
NADH
H2O
NAD+
malate
NAD+
H2O
isocitrate
NADH
fumarate
FADH2
FAD
a-ketogluterate
CoA
NAD+
NADH
succinate
CoA
succinyl–CoA
ATP
ADP + phosphate
group (from GTP)
Fig. 7.6, p. 115
Step 4
The
4-carbon compound
releases hydrogen
The hydrogen forms with
FAD+ to form FADH2.
FADH is another electron
acceptor.
PREPARATORY
STEPS
pyruvate
coenzyme A (CoA)
NAD+
(CO2)
NADH
CoA
Acetyl–CoA
KREBS CYCLE
CoA
oxaloacetate
citrate H O
2
NADH
H2O
NAD+
malate
NAD+
H2O
isocitrate
NADH
fumarate
FADH2
FAD
a-ketogluterate
CoA
NAD+
NADH
succinate
CoA
succinyl–CoA
ATP
ADP + phosphate
group (from GTP)
Fig. 7.6, p. 115
Step 5
The
4-carbon compound
releases a hydrogen to
REFORM oxaloacetic
acid
+
NAD is reduced again to
+
NADH and H
PREPARATORY
STEPS
pyruvate
coenzyme A (CoA)
NAD+
(CO2)
NADH
CoA
Acetyl–CoA
KREBS CYCLE
CoA
oxaloacetate
citrate H O
2
NADH
H2O
NAD+
malate
NAD+
H2O
isocitrate
NADH
fumarate
FADH2
FAD
a-ketogluterate
CoA
NAD+
NADH
succinate
CoA
succinyl–CoA
ATP
ADP + phosphate
group (from GTP)
Fig. 7.6, p. 115
Glycolysis, produces 2 NADH and 2
pyruvic acid, 2 ATP.
 One molecule of glucose from glycolysis
needs 2 turns of the Krebs to produce:
 Summary: 10 NADH, 2 FADH, 4 ATP, 4
CO2. The 10 NADH and 2 FADH (both
electron acceptors) will drive the next
stage of cellular respiration in the
Electron Transport Chain.

Electron Transport Chain
 ATP
is produced when NADH
and FADH2 release hydrogen
atoms, regenerating NAD+ and
FAD+.
 This occurs along the lining of the
inner membranes of the
mitochondria.
Steps of ETC
1. Electrons from the
hydrogens of NADH and
FADH2 are passed along
a series of molecules,
losing energy along the
way.
 2.
This energy pumps protons
from the matrix to the other
side of the membrane.
 A concentration gradient of
protons is created across the
inner membrane.
OUTER COMPARTMENT
NADH
INNER COMPARTMENT
Fig. 7.7a, p. 116

3. This
high concentration drives
chemiosmosis ( ATP production)
into the matrix. ATP synthase is
located in the inner membrane.
ATP is made as protons move
down their concentration gradient
in the mitochondria.
Oxygen’s Role




Oxygen is the final electron acceptor,
accepting electrons from the last molecule
in the ETC.
This allows ATP to continue to be
synthesized.
Oxygen also accepts the protons, part of
the hydrogen atoms from NADH and
FADH.
This combination of electron, protons and
oxygen forms WATER!!!!! O2 + e- +H- =
H2O
ATP
NADH
INNER
COMPARTMENT
ADP
+
Pi
Fig. 7.7b, p. 116
Energy Yield
 Per
molecule of glucose, 38
ATP’s are produced. 4 in
glycolysis and Krebs, 34 in ETC.
 66% efficiency
 C6H12O6 + 6O2  6CO2 + 6H2O +
energy
1 Pyruvate from
cytoplasm enters
inner mitochondrial
compartment.
OUTER COMPARTMENT
NADH
acetyl-CoA
Krebs
Cycle
NADH
NADH
3 NADH and
FADH2 give up
electrons and
H+ to membranebound electron
transport systems.
ATP
2 Krebs cycle and
preparatory steps:
NAD+ and FADH2
accept electrons and
hydrogen stripped
ADP
from the pyruvate.
+ Pi
ATP forms. Carbon
dioxide forms.
INNER COMPARTMENT
4 As electrons
move through the
transport system,
H+ is pumped to
outer compartment.
ATP
ATP
ATP
5 Oxygen
accepts
electrons,
joins with H+
to form water.
free oxygen
6 Following its gradients, H+ flows back
into inner compartment, through ATP
synthases. The flow drives ATP formation.
Fig. 7.5b, p. 114
Raw Materials of Photosynthesis
Light reaction
Dark Reaction





Light
C-A
ATP
NADPH
O2





Co2
RuBP
PGA
PGAL
Glucose
Important Raw materials
Glycolysis
Fermentation




Glucose
Pyruvic Acid
2 ATP
NADH




Pyruvic acid- reactant
Lactic Acid
Ethyl Alcohol
NAD
Important raw materials in the
Krebs Cycle
E.T.C.





Pyruvic acid – Acetyl
CoA
Acetyl-CoA –
Oxaloacetic AcidsCitric Acid
NADH and FADH
4 ATP
CO2




NADH
FADH
34 ATP
Water