This document contains notes from a lecture on cellular respiration. It defines key terms related to the process, including glycolysis, the Krebs cycle, the electron transport chain, oxidative phosphorylation, and chemiosmosis. It provides an overview of the stages of cellular respiration and summarizes the roles and reactions of important molecules like ATP, NAD+, FAD, glucose, and oxygen. Diagrams illustrate the structures involved and flow of electrons and protons between locations in the mitochondria.

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Cellular
Respiration!!
Whew! This stuff’s hard!!

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Thought I forgot the cat
picture??

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Cellular Respiration
• The controlled release of
energy in the form of
ATP from organic
compounds in cells.

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The Players in the Process
General: (words to apply in many places)
• Oxidize
• Reduce
• Lysis
• Phosphorylation
• Decarboxylation
• Chemiosmosis
• Mitochondria – outer, inner, cristae, intermembrane, matrix
• Cytoplasm - (cytosol)
• Aerobic
• Anaerobic

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More Players in the Process
Energy
• ADP
• ATP
Coenzymes
• NAD+
and NADH
• FAD and FADH2
Glycolysis
• Glucose
• PFK
• Pyruvate
• Substrate level
phosphorylation
Krebs Cycle
• Acetate
• CoA
• Acetyl-CoA
• Substrate level
phosphorylation
• Carbon Dioxide
Electron Transport
• ATP synthase
• Chemiosmotic
Oxidative
phosphorylation
• Oxygen
• Water
Fermentation
•lactic acid
• ethanol

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Key Vocabulary – THE PROCESSES
• Glycolysis
• Oxidative Decarboxylation (PDC)
• Krebs Cycle (Citric Acid)
• Electron Transport Chain
_______________________
• Fermentation – (anaerobic)
•Glycolysis

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Making Energy

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ATP, ADP and Glucose
ATP
• Usable cellular energy
• High energy in the bond that holds the 3rd
phosphate
(P) to the molecule.
• anabolic (synthesis)
ADP
• Has 2 phosphate (Pi) groups.
• Lower energy
• catabolism.
Glucose
• Has 90x the amount of “potential” energy than ATP
has.
• Cells can use glucose to “charge” ADP to ATP.

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PHOSPHORYLATION –
whenever any organic
molecule is a recipient of a
phosphate (P) group!
ADP to ATP

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Oxidation and Reduction
Oxidation
• Addition of oxygen
atoms to a
substance
• Removal of
Hydrogen from a
substance
• Loss of electrons
from a substance
Reduction
• Removal of oxygen
from a substance
• Addition of
hydrogen from a
substance
• Addition of
electrons to a
substance

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Oxidation and Reduction Rxns in
Cell Respiration
• Oxidizers in Cell Respiration:
• Glucose to pyruvate
• NADH to NAD+
• Reduced by Cellular Respiration
• NAD+ to NADH
• FAD to FADH2

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NAD+ and FAD
• ARE COENZYMES
• Every time a molecule GAINS electrons it
is reduced:
– NAD+ and FAD are electron carriers and
hydrogen acceptors
• All electrons carried by NAD+ or FAD will
be taken to the Electron Transport Chain
to undergo CHEMIOSMOSIS!

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Mitochondria
Outer membrane – encloses
mitochondria, contains protein
channels.
Inner Membrane – contains ETC and
ATP synthase that carry out oxidative
phosphorylation.
Cristae – tube like projections in the
inner membrane. Increases surface
area for oxidative phosphorylation.
Matrix – contains enzymes to run the
Krebs cycle
Intermembrane Space – used in the
ETC to hold hydrogen ions.
Draw on whiteboard!

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Cell Respiration –the equation
(the absolute minimum you need to know)
C6H12O6 + 6 O2 --> 6H2O + 6 CO2 +36 ATP
• OCCURS IN A SERIES OF SMALL REACTIONS USED TO
MAXIMIZE THE PRODUCTION OF ENERGY.
• OPERATES USING CHEMICAL REACTIONS AND ENZYMES:
• Enzyme + substrate ----- product + enzyme
TWO PHASES:
• ANAEROBIC(no oxygen required) – in CYTOPLASM

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Cell Respiration – an overview

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Respiration – An Overview

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GLYCOLYSIS – overview
• Anaerobic phase – occurs in cytoplasm.
• Common to nearly all living organisms
• Breaks down glucose into two smaller
molecules (two pyruvates)
• Glucose is OXIDIZED by NAD+
• Produces two ATP’s (net)
• Harvests high energy electrons.

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Draw on
Whiteboard!

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Glycolysis
Glycolysis animation

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Glycolysis
• IN CYTOPLASM:
• 2 ATP needed to change GLUCOSE:
•2 phosphates added:
– Hexose Bisphosphate (C6PP)
–Hexose Bisphosphate is LYSED into two
triose phosphate molecules.

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Glycolysis…continued
FORMATION OF PYRUVATE:
• Two atoms of Hydrogen are removed from
EACH triose molecule (oxidation)
• Removes high energy electrons: 2NAD+ to
2NADH (electron carrier) (REDUCED)
• Energy released is used to add a another
phosphate….2 triose biphosphate molecules.
• PHOSPHORYLATION of 4 ADP (to ATP)
MOLECULES (substrate level)
Leaving:
• Two – 3 CARBON COMPOUNDS: Pyruvate

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Energy from Glycolysis

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Energy Generated
2 ATP USED
4 ATP MADE
2 ATP NET - MADE AFTER
GLYCOLYSIS

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Draw on
Whiteboard!

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Oxidative Decarboxylation
Pyruvate
Dehydrogenase
Complex (PDC)

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Oxidative Decarboxylation
(link reaction)
FOR EACH PYRUVATE:
• A transition step --- in the matrix!
– Decarboxylation – a CO2 is removed by the
enzyme decarboxylase.
– Oxidation – a hydrogen is removed by the
enzyme dehydrogenase.
• Result
2 carbon molecule - acetyl group
– Acetyl group combines with Coenzyme A
forming Acetyl CoA

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Draw on
Whiteboard!

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The Krebs Cycle

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NADH + H+NAD+
CoA
CoA
NAD+
NAD+
NADH + H+
NAD+
NADH + H+
NADH + H+
FAD
FADH2
ATP
ADP
+ P
CO2
C
Pyruvic
Acid
C C C
Acetyl-CoA
C C
Citric Acid
C C C C C C
CO2
C
αKetoglutaric
Acid
C C C C C
Succinic
Acid
C C C C
CO2
C
Malic
Acid
C C C C
Oxaloacetic
Acid
C C C C

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The Krebs Cycle

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The Krebs Cycle
FOR EACH PYRUVATE:
1. 4C molecule joins Acetyl(2C) to form a 6C molecule.
2. 6C is broken down to 5C then to 4C
3. Along the way:
1. 2 more CO2 are released (decarboxylation)
2. 3 more NAD+ are reduced to NADH
(oxidation/reduction)
3. 1 FAD is reduced to FADH2 (oxidation/reduction)
4. 1 ADP is phosphorylated to ATP (subs. Level
phosphorylation)
4. A 4C molecule is recycled.

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Oxidative Decarboxylation &
The Krebs Cycle
Most Important Reminder
Since the diagrams represent 1 pyruvate:
ALL NUMBERS MUST BE
DOUBLED!!!!

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The Electron Transport Chain
Electron Transport Chain

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Intermembrane Space
Matrix
Inner Membrane
NAD+
FAD
NADH
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2

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Intermembrane Space
Matrix
Inner Membrane
NADH
NAD+
FAD
FADH2
~
e
ADP + P
ATP

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Chemiosmotic Oxidative
Phosphorylation
• The production of ATP relies on the
energy released by oxidation.
• Electron Transport Chain – series of
electron carriers.
• Inner mitochondrial membrane

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ETC
1. Electrons from NADH and FADH2 are passed into
the ETC. (Oxidation)
2. Electrons are passed from one carrier protein to
the next losing energy.
3. The “lost” electron energy pumps H+ ions through
protein channels across the membrane (by active
transport) creating a + charge in the
intermembrane and – charge in the matrix.
4. Electrons, Hydrogen ions, and O2 form WATER.
5. H+ move back into matrix thru ATP synthase.
6. This process releases energy causing ADP to
phosphorylate into ATP.

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Chemiosmotic Oxidative
Phosphorylation
Chemiosmosis – the process where protons (H+)
are diffused back through ATP Synthase from
the intermembrane space into the Matrix
Oxidative – use of an electron transport chain;
electrons transferred to Oxygen.
Phosphorylation – ADP to ATP through ATP
Synthase.

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The Role of Oxygen
• At the end of the ETC, electrons are
“given” to oxygen.
• Oxygen “accepts” hydrogen ions to form
WATER.
– In the matrix of the mitochondria.
– Only stage where Oxygen is used.
• Without O2, the NADH cannot give up
its H+ ions. This will stop the
mitochondrial part of cell respiration.
• Glycolysis can continue = fermentation

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Counting the ATP
• For every NADH that is produced, 3
ATP’s can be generated through
chemiosmosis.
• For every FADH2 that is produced 2
ATP’s can be generated through
chemiosmosis.
• Let’s Do the math…

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Process
NADH FADH2
Direct
ATP’s
Chemi-
osmosis
Glycolysis
PDC
Krebs
Cycle

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The Grand Total
• TWO ATP are also used to “shuttle” the
NADH from the cytoplasm to the
Mitochondria after GLYCOLYSIS.
38–2=36 ATP:Net from ACR
Efficiency of Respiration::::::::::::::

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Mitochondria and Respiration

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Respiration Without Oxygen:
Anaerobic Cellular Respiration

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WHITEBOARD!!!

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Fermentation
• Anaerobic Respiration
• Glycolysis occurs BUT…
• Pyruvate is REDUCED to either lactic acid or
ethanol
– 2CO2 are “released,” 2 NADH (oxidized) are
“recycled” in Alcohol Fermentation: Ethanol(2C)
(reduced)
– 2 NADH are “recycled” : Lactic Acid(3C) Fermentation
• NAD+ reused
• 2 ATP generated – enuf for simple organisms

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Industrial Advantages
• Alcohol:
– Beverages – grapes incubated at the correct
temperature with bacteria or yeast
• CO2 is kept – “sparkling” wine.
• Lactic Acid:
– Yogurt production – lactobacillus and
lactococcus bacteria
• Makes milk sour and clot
– ***Humans – under high energy demand.
Muscle cells will ferment producing lactic acid
– PAIN.

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