1 Review What happens to pyruvic acid in the Krebs
cycle
Interpret Visuals Look at the diagram of the Krebs
cycle. List all the products that are made and
include what happens to each one
2 Review How does the ETC use the high energy
electrons from glycolysis and the Krebs cycle
Relate Cause and Effect How does the cell use the
charge differences that build up across the inner
mitochondrial membrane during cellular
respiration
CH 9 CELLULAR RESPIRATION AND
FERMENTATION
9.2 The Process of Cellular Respiration
Glycolysis



First stage of cellular
respiration
Glucose is broken
down into 2 molecules
of the 3-carbon
molecule pyruvic acid
ATP and NADH are
produced.
Glycolysis

Cells “deposits” 2 ATP
to start glycolysis.
Glycolysis

Produces 4 ATP molecules
 Net
gain of 2 ATP for each
glucose.
Glycolysis

NAD+ accepts a pair of
high-energy electrons
and becomes NADH
 Happens
twice
 Goes to ETC.
Glycolysis


Produces ATP very fast
Does not need oxygen.
Krebs Cycle



Pyruvic acid is broken down
into carbon dioxide
A.k.a. Citric Acid Cycle
ATP is produced.
Krebs Cycle 1

Pyruvic acid from
glycolysis enters the
matrix of the
mitochondrion.
Krebs Cycle 2



Enzymes split CO2 off
from pyruvic acid
Leaves 2 carbon
molecule
NADH is produced form
NAD+.
Krebs Cycle 3

2 carbon molecule joins
a 4 carbon molecule to
make citric acid.
Krebs Cycle 4


Citric acid (6 carbon)
becomes a 4 carbon
molecule
More NADH and CO2
are made.
Krebs Cycle 5

More reactions capture
energy as ATP, NADH,
and FADH2.
Krebs Cycle 6

4 carbon molecule goes through cycle again.
Krebs Cycle


Each glucose molecule
will make two turns of
the Krebs cycle
Each glucose molecule
will make
2
ATP molecules
 8 NADH molecules
 2 FADH2.
Electron Transport

NADH and FADH2 pass their electrons to ETC.
Electron Transport

Electrons combine with H+ ions and oxygen to form
water at end of ETC.
Electron Transport

The high energy electrons move H+ ions against a
concentration gradient across the inner
mitochondrial.
Electron Transport


H+ ions pass back through
the ATP synthase causing it to
spin
ATP synthase attaches a
phosphate to ADP to produce
ATP with each rotation.
Energy Totals


Complete breakdown
of glucose through
cellular respiration
results in the
production of 36 ATP
molecules
The rest of the energy
is “lost” as heat (64%).