Chapter 9
Cellular Respiration:
Harvesting Chemical
Energy
Is this a process of
turning food into energy?
Rs - Equation
C6H12O6 + 6 O2
6 CO2 + 6 H2O
and energy
The energy is released from the
chemical bonds in the complex
organic molecules.
Respiration - Preview
The
process of releasing
Energy from food.
Food - Stored Energy in
chemical bonds.
ATP - Useable Energy for cell
work.
Focus of Chapter
1. Purpose - what is the
reaction suppose to do?
2. Location - where is it at?
3. Requirements - what is
needed to make it run?
4. Products - what does it
produce?
Oxidation - definitions
Loss
of electrons.
Loss of energy.
Loss of Hydrogens from
Carbons.
Reduction - definitions
Gain
of electrons.
Gain of energy.
Gain of Hydrogens to
Carbons.
Comment - be careful not to
use “reduction” in lay terms.
Redox reactions
Redox reactions
Reactions
are usually paired
or linked together.
Look for these links as we
study Rs.
Many of the reactions will be
done by phosphorylation
Phosphorylation
Adding
a phosphate group to
a molecule.
The phosphate group adds
“energy” to the molecule for
chemical reactions.
Phosphorylation
Cell Respiration - parts
1. Glycolysis
2. Krebs Cycle
3. Electron Transport Chain
Glycolysis
Glyco-
glucose.
-lysis: to split
Universal step in all Rs types.
Likely to earliest type of cell
energy processes.
Glycolysis
Function
- To split glucose
and produce NADH and ATP.
Location - Cytoplasm.
Electron Carrier
Compounds
Molecules
that transport or
shuttle electrons within the
cell.
Exist it two forms:
Oxidized
(ox)
Reduced (red)
NAD
Nicotinamide
Adenine
Dinucleotide
NAD+ + 2 eNADH
NAD+ = oxidized form
NADH = reduced form
Glycolysis -Requirements
Glucose
2
ATP
4 ADP
2 NAD+
Glycolysis - Products
2
Pyruvic Acids (a 3C acid)
2 ADP
4 ATP
2 NADH
Net Result
2
ATP per glucose
2 NADH
Energy Investment Phase
Energy Harvest Phase
Let’s
check out the reaction as it
happens…
Go
to here
http://www.science.smith.edu/de
partments/Biology/Bio231/
And click on “Glycolysis”
Krebs Cycle
Also
called:
Citric
Acid Cycle
Tricarboxylic Acid Cycle
Krebs Cycle
Function:
Oxidize pyruvic
acid to CO2
Produce NADH and FADH2
Location: Mitochondria
matrix
Formation of Acetyl CoA
Krebs Cycle -Requirements
Pyruvic
acid (3C acid)
Coenzyme A
4 NAD+
1 ADP
1 FAD
Double this list for each
glucose.
Krebs Cycle - Products
3
CO2
Acetyl CoA
4 NADH
1 ATP
1 FADH2
Double this list for each
glucose.
Krebs Cycle
Produces
most of the cell's
energy in the form of NADH
and FADH2
Does NOT require O2
Comment
The
ATPs produced directly
in Krebs Cycle and in
Glycolysis are by:
Substrate-level
phosphorylation
The Pi group is transferred
from a substrate to ADP.
 Let’s
see how the Krebs cycle
works…
 Go
to here
http://www.science.smith.edu/depart
ments/Biology/Bio231/
 And click on “Citric Acid Cycle”
 Just
another name for the Krebs Cycle!
Electron Transport
Chain
ETC
or Electron Transport
System (ETS).
A collection of proteins that
are structurally linked into
units.
ETC
Uses
sets of Cytochromes, Fe
containing proteins to pass
electrons.
The Cytochromes alternate
between RED and OX forms
and pass electrons down to O2
ETC
Function:
Convert NADH and
FADH2 into ATP.
Location: Mitochondria
cristae.
ETC - Requirements
NADH
ADP
O2
or FADH2
ETC - Products
NAD+
ATP
H2O
and FAD
ETC - ATP Yields
Each
NADH -- 3 ATP
Each FADH2 -- 2 ATP
Chemiosmotic
Hypothesis
ETC
energy is used to move
H+ (protons) across the
cristae membrane.
ATP is generated as the H+
diffuse back into the matrix.
ATP Synthase
Uses
the flow of H+ to make
ATP.
Works like an ion pump in
reverse, or like a waterwheel
under the flow of H+ “water”.
Let’s
Go
see how the ETC works!
to here
http://www.science.smith.edu
/departments/Biology/Bio231/
And click on “ ETC”
Super
mega awesome tutorial
at this site:
http://student.ccbcmd.edu/bi
otutorials/cellresp/cellresp_in
dex.html
Let’s go! Here
Catabolism of Proteins
and Fats
 Can
use these as energy sources as
well!
 Proteins first broken down into AA’s
 Amino group (containing N) is
removed from each AA by
deamination
 Converts
the remaining C chain into a
molecule to be used in the Krebs Cycle
or Glycolysis
Cell Resp of Fat

Fats are broken down into FA + glycerol

-CH2 links and many H+ in tails provide much
energy

FA oxidized in mitochondria where enzymes
remove the 2C acetyl groups from whole FA
until all is converted – goes to bind w/
coenzyme A = acetyl-CoA

Process is “b oxidation”
 Results?
 Respiration
of a 6C FA yields 20% more
ATP than the same glucose
 Also weighs less than 2/3 as much as
glucose, therefore gram for gram, fat
has more kilocalories than glucose
 Let’s see that in motion!
 http://nutrition.jbpub.com/resources/animati
ons.cfm?id=23&debug=0
Alcoholic Fermentation
Done
by yeast, a kind of
fungus.
Alcoholic Fermentation
Uses
only Glycolysis.
An incomplete oxidation energy is still left in the
products (alcohol).
Does NOT require O2
Produces ATP when O2 is not
available.
Lactic Acid
Fermentation
Uses
only Glycolysis.
An incomplete oxidation energy is still left in the
products (lactic acid).
Does NOT require O2
Produces ATP when O2 is not
available.
Lactic Acid
Fermentation
Done
by human muscle cells
under oxygen debt.
Lactic Acid is a toxin and
causes soreness and
stiffness in muscles.
Fermentation Summary
Way
of using up NADH so
Glycolysis can still run.
Provides ATP to a cell even
when O2 is absent.
Aerobic vs Anaerobic
Aerobic
- Rs with O2
Anaerobic - Rs without O2
Aerobic - All three Rs steps.
Anaerobic - Glycolysis only.
Strict vs. Facultative
Strict
- can only do Rs this
one way.
Facultative - can switch Rs
types depending on O2
availability. Ex - yeast
Question
Since
yeast can do both
aerobic and anaerobic Rs,
which is the better process if
given a choice?
Check the ATP yields from
both processes.
ATP yields by Rs type
Anaerobic
- Glycolysis only
Gets 2 ATPs per glucose.
Aerobic - Glycolysis, Krebs,
and ETC. Generates many
more ATPs per glucose.
Aerobic ATP yield
Glycolysis
- 2 ATPS, 2 NADHs
Krebs - 2 ATPS, 8 NADHs,
2 FADH2
Each NADH = 3 ATP
Each FADH2 = 2 ATP
ATP Sum
10



NADH x 3 = 30 ATPs
2 FADH2 x 2 =
4 ATPs
2 ATPs (Gly) = 2 ATPs
2 ATPs (Krebs) = 2 ATPs
Max
= 38 ATPs per glucose
However...
Some
energy is used in
shuttling the NADH from
Glycolysis into the
mitochondria.
Actual ATP yield ~ 36/glucose
Yeast
Would
rather do aerobic Rs;
it has 18x more energy per
glucose.
But, anaerobic will keep you
alive if oxygen is not present.
Importance of Rs
Convert
food to ATP.
Provides materials for use in
other cellular pathways.
Other Importances of
Respiration
Alcohol
Industry - almost
every society has a
fermented beverage.
Baking Industry - many
breads use yeast to provide
bubbles to raise the dough.
Question
Why
is the alcohol content of
wine always around 12-14%?
Alcohol is toxic and kills the
yeast at high concentrations.
Swiss Cheese
Holes
are bubbles of CO2
from fermentation.
Summary
Know
the 3 main reactions of
Rs and the 4 required items
for each.
Appreciate the importances
of Rs.
Rs - Equation
C6H12O6 + 6 O2
6 CO2 + 6 H2O
and energy
Which part of the equations
represent which of the 3 Rs
reactions?
Matching
Sugar Cane
Barley
Grapes
Juniper Cones
Agave Leaves
Rice
Potatoes
Gin
Saki
Tequila
Vodka
Beer
Wine
Rum
Answers!!
 Sugar
cane
Rum
 Barley
Beer
 Grapes
Wine
 Juniper
Gin
 Agave
Tequila
 Rice
Saki
 Potatoes
Vodka
 Remember…no partaking until you’re 21! 