Cellular Respiration
Let’s Review
Is a chemical process that uses
oxygen to convert chemical energy
stored in organic molecules into
another form of chemical energy –
a molecule called ATP
 Cells in plants and animals then
use the ATP as their main energy
supply.

Energy
The ability to perform work
 Ex: your heart muscle does work
every time it beats
 Two basic forms of energy
 Potential
 kinetic

Potential Energy
 Is
stored energy due to an
object’s position or
arrangement
Kinetic Energy



Energy of motion
Anything that is moving
Kinetic - “motion”
Thermal Energy
 Energy
that has been
transferred
 From areas that are warmer to
cooler
Chemical Energy
 Organic
compounds store
energy (potential) in the
way their atoms are
arranged.
 This is called chemical
energy
ATP - Nature's Energy Store
All living things, plants and animals,
require a continual supply of energy
in order to function.
The energy is used for all the
processes which keep the organism
alive.
Before the energy can be used,
it is first transformed into a form
which the organism can handle
easily.
 This special carrier of energy is
the
molecule
adenosine
triphosphate, or ATP.


Its Structure
 The
ATP molecule is
composed of three
components.
 At the center is a sugar
molecule, ribose

(the same sugar that forms the
basis of RNA).
Attached to one side of this is a base
(a group consisting of linked rings of
carbon and nitrogen atoms); in this
case the base is adenine.
 The other side of the sugar is
attached to a string of phosphate
groups.
 These phosphates are the key to the
activity of ATP.

ATP consists
of a base, in
this case
adenine
(red), a
ribose
(magenta)
and a
phosphate
chain (blue).
How it works
ATP works by losing the endmost
phosphate group when instructed
to do so by an enzyme.
 This reaction releases a lot of
energy, which the organism can
then use to build proteins, contact
muscles, etc

The reaction product is
adenosine diphosphate
(ADP),
ATP
ADP
Even
more energy can
be extracted by removing
a second phosphate
group to produce
adenosine
monophosphate (AMP).
AMP


When the organism is resting and
energy is not immediately needed, the
reverse reaction takes place and the
phosphate group is reattached to the
molecule using energy obtained from
food or sunlight.
he ATP molecule acts as a chemical
'battery', storing energy when it is not
needed, but able to release it instantly
when the organism requires it.

The Phosphorus Cycle

The fact that ATP is Nature's
'universal energy store' explains
why phosphates are a vital
ingredient in the diets of all living
things. Modern fertilizers often
contain phosphorus compounds
that have been extracted from
animal bones.
These compounds are used by
plants to make ATP. We then eat
the plants, metabolise their
phosphorus, and produce our
own ATP. When we die, our
phosphorus goes back into the
ecosystem to begin the cycle
again...
Cellular Respiration
Cellular Respiration

A catabolic, exergonic, oxygen (O2)
requiring process that uses energy
extracted from macromolecules
(glucose) to produce energy (ATP)
and water (H2O).
C6H12O6 + 6O2  6CO2 + 6H2O + energy
glucose
ATP
Question:
 In
what kinds organisms
does cellular respiration
take place?
Plants and Animals
 Plants - Autotrophs: selfproducers.
 Animals
- Heterotrophs:
consumers.
Mitochondria

Organelle where cellular respiration takes place.
Outer
membrane
Inner
membrane
Inner
membrane space
Matrix
Cristae
Breakdown of Cellular Respiration

Three main parts (reactions).
1. Glycolysis (splitting of sugar)
a. cytosol, just outside of mitochondria.
Breakdown of Cellular Respiration
2. Krebs Cycle (Citric Acid Cycle)
a. mitochondrial matrix
3. Electron Transport Chain (ETC
a.. inner mitochondrial membrane.
1. Glycolysis


Occurs in the cytosol just outside of
mitochondria.
Two phases:
A. Energy investment phase
a. Preparatory phase
B. Energy yielding phase
a. Energy payoff phase
1. Glycolysis
A. Energy Investment Phase:
Glucose (6C)
C-C-C-C-C-C
2ATP
2 ATP - used
0 ATP - produced
0 NADH - produced
2ADP +
P
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
C-C-C
C-C-C
1. Glycolysis
B. Energy Yielding Phase
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
GAP
GAP
C-C-C C-C-C
4ADP +
P
4ATP
0 ATP - used
4 ATP - produced
2 NADH - produced
C-C-C C-C-C
(PYR)
(PYR)
Pyruvate (2 - 3C)
(PYR)
1. Glycolysis

Total Net Yield
2 - 3C-Pyruvate (PYR)
2 - ATP
2 - NADH
2. Krebs Cycle (Citric Acid Cycle)

Location: mitochondrial matrix.

Acetyl CoA (2C) bonds to Oxalacetic acid (4C
- OAA) to make Citrate (6C).

It takes 2 turns of the krebs cycle to oxidize 1
glucose molecule.
Mitochondrial
Matrix
2. Krebs Cycle (Citric Acid Cycle)
1 Acetyl CoA (2C)
OAA (4C)
Citrate (6C)
Krebs
Cycle
FADH2
(one turn)
2 CO2
3 NAD+
FAD
3 NADH
ATP
ADP + P
2. Krebs Cycle (Citric Acid Cycle)
2 Acetyl CoA (2C)
Citrate (6C)
OAA (4C)
4 CO2
Krebs
Cycle
2 FADH2
(two turns)
6 NAD+
2 FAD
6 NADH
2 ATP
2 ADP +
P
2. Krebs Cycle (Citric Acid Cycle)

Total net yield (2 turns of krebs cycle)
1. 2 - ATP (substrate-level phosphorylation)
2. 6 - NADH
3. 2 - FADH2
4. 4 - CO2
3. Electron Transport Chain (ETC) and
Oxidative Phosphorylation (Chemiosmosis)

Location: inner mitochondrial membrane.

Uses ETC and ATP Synthase (enzyme) to make
ATP.

ETC pumps H+ (protons) across innermembrane
(lowers pH in innermembrane space).
Inner
Mitochondrial
Membrane
3. Electron Transport Chain (ETC) and
Oxidative Phosphorylation (Chemiosmosis)

The H+ then moves via diffusion through ATP
Synthase to make ATP.

All NADH and FADH2 converted to ATP during
this stage of cellular respiration.

Each NADH converts to 3 ATP.

Each FADH2 converts to 2 ATP (enters the ETC
at a lower level than NADH).
TOTAL ATP YIELD
1. 04 ATP – glycolysis and krebs cycle
2. 34 ATP - ETC
38 ATP - TOTAL YIELD
ATP
Maximum ATP Yield for Cellular
Respiration (Eukaryotes)
Glucose
Cytosol
Mitochondria
Glycolysis
2 Acetyl CoA
2 Pyruvate
Krebs
Cycle
2NADH
2 ATP
6NADH
2FADH2
(substrate-level
phosphorylation)
2NADH
ETC and Oxidative
Phosphorylation
2 ATP
(substrate-level
phosphorylation)
2ATP
4ATP 6ATP
18ATP
4ATP
36 ATP (maximum per glucose)
2ATP
Fermentation

Occurs in cytosol when “NO Oxygen” is present
(called anaerobic).

Remember: glycolysis is part of fermentation.

Two Types:
1. Alcohol Fermentation
2. Lactic Acid Fermentation
Alcohol Fermentation

Plants and Fungi
C
C
C
C
C
C
2ADP
+2 P
glucose
beer and wine
2ATP
2NADH
2 NAD+
C
C
C
Glycolysis
2 NAD+

2NADH
2 Pyruvic
acid
C
C
2CO2
released
2 Ethanol
Lactic Acid Fermentation

Animals (pain in muscle after a workout).
C
C
C
C
C
C
2ADP
+2 P
2NADH
Glycolysis
2 NAD+
Glucose
2ATP
2NADH
2 NAD+
C
C
C
C
C
C
2 Pyruvic
acid
2 Lactic
acid
Lactic Acid Fermentation

End Products: Lactic acid fermentation
2 - ATP
2 - Lactic Acid molecules
Alcohol Fermentation

End Products: Alcohol fermentation
2 - ATP
2 - CO2
2 – molecules of ethanol
Question:
 In
addition to glucose, what
other various food molecules
are use in Cellular Respiration?
Catabolism of Various
Food Molecules

Other organic molecules used for fuel.
1. Carbohydrates: polysaccharides
2. Fats: glycerol’s and fatty acids
3. Proteins: amino acids