The Big Picture
The Circle of Life...
 Photoautotophs: organisms that can build all the organic
compounds required for life from simple
________________ materials, using _____________ in the
process.
 Green plants and photosynthetic microorganisms
 Heterotrophs: organisms that feed on other organisms to
obtain _____________ energy.
 Animals, fungi, most protists and bacteria
 Chemoautotrophs: organisms that can build all the organic
compounds required for life from simple _______________
materials without using _____________ energy.
 Some archaebacteria
 Likely the first organisms on Earth
Glucose
 With the exception of chemoautotrophs, all organisms
use glucose.
 Through a series of enzyme-controlled redox
reactions, covalent bonds broken and rearranged into
more stable configurations.
 Therefore, a _______________ of energy.
Aerobic Cellular Respiration
 glucose is oxidized to carbon dioxide and oxygen is
reduced to water.
 Takes about 20 reactions.
 Aerobic Cellular Respiration: oxygen is used.
Oxidation of Glucose
 Contains number of C-h bonds.
 Oxygen oxidizes these bonds in two ways
 C-H bonds relatively nonpolar (0.4), therefore, electron
pairs are shared almost ____________. 12 hydrogen
atoms break away from glucose and attach to six oxygen
atoms from the six oxygen (O2) molecules  six H2O
molecules.
 Called oxidation: hydrogen atoms carry electrons away
from the carbon atoms.
 When H forms covalent bonds with oxygen, shared
electron pairs occupy positions closer to the oxygen nuclei
than they did when they were part of glucose.
 H moves from EN C atoms in glucose to highly EN oxygen
atooms  lose potential energy.
 Decrease in potential energy + increase in entropy 
decrease in free energy (of the system)  overall exergonic
process.
What about the Carbon Dioxide?
 Remaining oxygen atoms must be attached to carbon
atoms, forming the six carbon dioxide molecules on
the product side of the overall equation.
 C-O bonds are polar, therefore, oxidation reaction.
 More stable configuration  release of free energy.
Aerobic Oxidation of Glucose
 Overall: involves the movement of valence electrons
from a higher free energy state in glucose to a lower
free energy state in carbon dioxide and water.
 Decrease in potential energy, increase in entropy.
Combustion of Glucose
 When glucose is burned in test tube, carbon dioxide,
water, and heat + light (flame) are formed.
 It would not be good for the glucose in living cells to
combust and give off energy as heat.
 Cells have evolved methods to trap energy (about 34%).

Positions of electrons in certain molecules (like ATP) moved
to higher free energy states  become readily available source
of free energy to power _______________processes.
Glucose and Activation Energy
 If reaction occurred every time glucose and oxygen
came into contact, ____________________________.
 All living things would be converted to
________________, ___________________, and
___________________.
 Amount of ________________________ needed for
combustion of glucose is relatively high.
 Therefore, ______________ needed!
Enzymes and Respiration
 Specific enzymes catalyze every step in the aerobic
respriration process.
 Lower _________________________ and allow
reactions to occur at a rate that is __________________
with the needs of the _____________.
 Available free energy transferred to a number of
energy-carrier molecules, including _______.
Spontaneous Human Combustion?
 What do you think?
http://www.youtube.com/watch?v=yYyBPdxS2e8&feature=related
Other ways of Obtaining Energy
 Obligate Aerobes: have to use aerobic respiration: obtain
energy by oxidizing organic substances using oxygen.
 _______________, ___________________, ______________,
__________
 Obligate Anaerobes: cannot live in the presence of oxygen
and obtain energy by oxidizing inorganic substances (NO2,
SO4, CO2, and Fe3+ )
 Mostly bacteria
 Examples: Clostridium tetani (tetanus), Clostridium
perfringens (gas gangrene).
 Facultative Anaerobes: obtain energy by oxidizing
inorganic substances with or without oxygen
 mostly bacteria
 Examples: Vibrio cholerae (colera) and Salmonella
enteritidis (food poisoning).
Summary
Classwork/Homework
Pg. 93, #1-5
Cellular Respiration – Introduction
to the Details
 There are many steps to cellular respiration, and it may
seem overwhelming at times. Keep in mind the overall
equation:
_______________________________________________
There are three overall goals of the process
1) To break 6 C-C bonds in glucose to make 6 CO2
2) To move hydrogen atom electrons from glucose to
oxygen, forming 6 H2O.
3) To trap as much of the free energy released in the process
as possible in the form of _____.
Parts of the Mitochondria
Cell Respiration can be divided into 4 Parts:
1) Glycolysis
2) Oxidation of Pyruvate / Transition Reaction
3) The Krebs Cycle
4) The Electron Transport Chain and
Chemiosmotic Phosphorylation
1) Glycolysis
 10-step process occurring in the cytoplasm.
 Glucose  pyruvate
 Uses substrate-level
phosphorylation.
 ATP is formed
2) Pyruvate Oxidation
1-step process occuring in the mitochondrial matrix
 Pyruvate acetyl CoA
 Releases NADH
3) The Krebs Cycle
 Also called the
tricarboxylic acid
cycle, TCA or the
citric acid cycle.
 8-step cylical process
occurring in the
mitochondrial matrix
4) Electron Transport and Chemiosmosis
(oxidative phosphorylation)
 Multistep process
occuring in the inner
mitochondrial
membrane.
Ultimate Goal for all of these
steps?
To ________________ energy from nutrient molecules
and store it in a form that the ____________ can use
for its many and varied _____________-requiring
activities.
The primary energy transfer is from ______________ to
__________________.
Energy Transfer
 Cell wants to capture as much of the available free
energy as possible in the form of ___________.
 Two energy-transfer mechanisms
 Substrate-level phosphorylation
 Oxidative phosphorylation
Substrate-Level Phosphorylation
 ATP formed directly in an enzyme-catalyzed reaction.
 Phosphate-containing compound transfers a
phosphate group directly to ADP.
ADP + Pi + energy  ATP
∆G= 31 kJ/mol
 For each glucose molecule processed
 4 ATP generated this way in glycolysis
 2 ATP generated this way in the Krebs cycle
Oxidative Phosphorylation
 APT formed indirectly
 Involves a series of redox reactions, with oxygen being
the final electron acceptor.
 Much more complex than substrate-level
phosphorylation!
 Steps in Oxidative Phosphorylation
FORMING NADH
1) Coenzyme Nicotinamide adenine dinucleotide,
NAD+: removes 2 hydrogen atoms (2P + 2e-) from
portion of original glucose molecule.
2) Dehydrogenase enzyme: 2e- and 1P attach to NAD+
 _______. Remaining proton dissolves into solution
as _______.


NAD+  __________________ form
NADH  __________________ form
FORMING FADH2
1) Coenzyme FAD is reduced by two hydrogen atoms
from a portion of the original glucose molecule. FAD +
2e- + 2P  FADH2.
So, what’s the point of forming
NADH and FADH2?
 All reduced coenzymes formed within first three
statges (glycolysis, pyruvate oxidation, Krebs Cycle)
 The reductions of NAD+ to NADH and FAD to FADH2
are energy-harvesting reactions
 Act as mobile energy carriers within the cell
 Will eventually transfer most of free energy to ATP
during electron transport & chemiosmosis.
Anaerobic Respiration (no oxygen required, cytoplasm)
1. Glycolysis
(substrate level)
Glucose
2 ATP

4 ATP (Net 2 ATP)
2 NADH
2 Pyruvate
Aerobic Respiration (oxygen required, mitochondria)
2. Oxidation
of
Pyruvate
2 Pyruvate

2 CO2
2 NADH
2 Acetyl CoA
3. Krebs Cycle
(substrate level)
2 Acetyl CoA

4 CO2
2 ATP
6 NADH
2 FADH2
4. Electron
Transport
Chain
(chemiosmotic)
10 NADH
2 FADH2
6 O2

6 H2O
32 ATP
Total: 36 ATP produced
Ideas for Assignment?