Cellular Respiration
Introduction
Organisms that must eat food to get
energy are called heterotrophs. They
consume glucose which is broken
down in the cell and the mitochondria
to create energy.
Cellular respiration is the process that
breaks down glucose to give off energy.
Overview
Ultimately, all of cellular respiration looks
like this:
C6H12O6 + 6O2  6CO2 + 6H2O
Introduction
There are two basic locations that glucose
is broken down:
The Cytoplasm
&
The Mitochondria
In the Cytoplasm
ENZYMES
From Chloroplasts (autotrophs)
PYRUVATE
From Food (heterotrophs)
PYRUVATE
Glycolysis
ATP ATP
… a fork in the road …
In animals, if not
enough oxygen is
present, the 2
pyruvate molecules
are converted into
lactic acid! This is
a type of
fermentation that
leads to muscle
cramps.
LACTIC
ACID
LACTIC
ACID
… a fork in the road …
If there is enough
oxygen present, the
2 pyruvate
molecules are
converted to Acetyl
CoA, give off CO2
and enter the
mitochondrion.
Acetyl CoA
CO2
Acetyl CoA
CO2
MITOCHONDRION
A Summary of Glycolysis
1. Glucose is broken down in a series of steps
by enzymes into 2 pyruvate molecules.
2. This produces a gain of: 2 ATP and NADH
molecules.
3. The 2 pyruvate molecules give off CO2 and
are converted into Acetyl CoA if enough
oxygen is present.
(If not, the pyruvate is fermented)
Inside the Mitochondrion
The Mitochondrial Matrix
The Krebs cycle
The Krebs cycle
strips electrons from
Acetyl CoA and
gives them to
electron carriers:
Acetyl
ATPCoA
ATPCoA
Acetyl
NAD+  NADH
FAD  FADH2
Two more ATP molecules are also produced.
A Summary of the Kreb’s Cycle
1. Acetyl CoA is broken down in a series of
steps by enzymes.
2. This produces a gain of: 2 ATP, more NADH
molecules, and FADH2 molecules.
In the Mitochondrion
The Inner Membrane
MITOCHONDRION
ATP
ATP
ATP
ATP
ATP
ATP
Electron
Transport
Chain
ATP
ATP
ATPATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
The electron transport chain is used to
create 32 more molecules of ATP.
Intermembrane Space
H
H
H
H
H
H
H
H
ATP
Synthase
NAD+
O
H
H
H
H
Matrix
H
H
P P P P
H
H
H
H
H
H
A Summary of the Electron Transport Chain
1. NADH and FADH2 drop off electrons at the
start of the electron transport chain.
2. Electrons provide energy to actively
transport hydrogens from the matrix to the
innermembrane space.
3. Electrons are joined with oxygen and
hydrogens to make water.
4. Hydrogens diffuse through ATP synthase
BACK into the matrix to make 32 MORE
ATP molecules.
Review
 Glycolysis:


In: glucose, ADP, P, NAD+
Out: 2 ATP, NADH, CO2, 2 Pyruvate  2 Acetyl CoA
 Krebs Cycle:


In: Acetyl CoA, ADP, P, NAD+, FAD
Out: 2 ATP, NADH, FADH2
 Electron Transport Chain:


In: oxygen, NADH, FADH2
Out: 32 ATP, H2O, NAD+, FAD