F. Electron Transport Chain [ETC]
1. Overview
a this occurs in the cristae membrane of the mitochondria
b. a series of oxidation reduction reactions that converts
the stored energy in NADH+H+ or FADH2
indirectly into ATP
c. the process involves moving electrons between proteins
within the membrane and this results in
proton movement across the membrane
2. Accessing the NADH+H+ and FADH2
Kreb’s cycle occurs in mitochondrial matrix  2 x 3 NADH+H+
2 x 1 FADH2
oxidation of pyruvate occurs
in mitochondria matrix 
2 x 1 NADH+H+
glycolysis occurs in the cytoplasm
1 x 2 NADH+H+
3. Getting the energy into the mitochondria from
the cytoplasm
NADH+H+ from the cytoplasm can not pass through
the inner mitochondrial membrane and therefore
can not directly enter the ETC
however, the energy stored in NADH+H+ can be
passed across the membrane with the electrons
to a molecule of FADH2
glycerol phosphate shuttle protein
NADH+H+
2H+
2e-
NAD+
FAD
FADH2
inner mitochondrial membrane
ELECTRON TRANSPORT CHAIN
1 – NADH dehydrogenase
4 – cytochrome C
2 – protein Q
5 – cytochrome oxidase
3 – cytochrome b-c1
6 – ATP synthase
4
1
3
2
5
6
2H+
2H+
2H+
2H+
4
1
3
5
6
2
2e-
FADH2
NADH + H+
½ O2 + 2H+
FAD
NAD+
2H+
H20
2H+
ADP + Pi
2H+
ATP
2H+
4. Proteins
a. NADH dehydrogenase – accepts 2 electrons from NADH+H+
and passes them on - 2 H+ [protons] follow the electrons &
pass through the membrane
b. protein Q - accepts 2 electrons from NADH dehydrogenase
or FADH2 and passes them on
c. cytochrome b-c1 complex - accepts 2 electrons from
protein Q and passes them on - 2 H+ [protons] follow
the electrons & pass through the membrane
d. cytochrome c - accepts 2 electrons from cytochrome b-c1
complex and passes them on
e. cytochrome oxidase complex - accepts 2 electrons from cytochrome c
& passes them on to oxygen [1/2 O2]
- 2 H+ follow the electrons & pass through the membrane
6. tally of H+ across the membrane
a. for every NADH+H+

3 pairs of H+ are pumped
into the intermembrane space
b. for every FADH2

2 pairs of H+ are pumped
into the intermembrane space
7. ATP synthetase
[not technically part of the ETC]
a. there are more H+ in the intermembrane space than in the matrix
b. the H+ try to move down a concentration gradient back
across the membrane
c. the H+ can not pass through the phospholipid membrane directly
d. the enzyme ATP synthetase allows the H+ to pass through it
e. as the H+ pass through the ATP synthetase they distort its shape
and when it returns to its normal shape it is able to
add Pi + ADP  ATP + H2O
8. Summary
pg 108 Fig. 22 for information
9. Overall summary
pg 110 Fig 25 recommend copying this
SUMMARY OF PHOTOSYNTHESIS and AEROBIC RESPIRATION
chloroplast
glucose
mitochondria
light
CO2
light reaction
C-4 cycle
ATP; NADPH +H+
Calvin cycle
H2 O
chloroplast
O2
cellulose
glucose
glucose
O2
ATP
H2 O
NADH + H+
FADH2
ETC
glycolysis
pyruvate
CO2
FAD
NADH + H+
NADH + H+
FADH2
oxidation of pyruvate
Kreb’s cycle
mitochondria
ATP
ATP
CO2