Cellular respiration is a series of reactions that occur in cells to break down glucose and produce ATP. It involves glycolysis in the cytoplasm, which produces 2 ATP and 2 pyruvate. The pyruvate then enters the mitochondria, where it undergoes oxidative decarboxylation and the Krebs cycle, producing more ATP, NADH, and FADH2. These electron carriers are used in the electron transport chain to pump protons across the inner mitochondrial membrane, driving ATP synthesis. Aerobic respiration is more efficient at producing ATP than anaerobic respiration such as lactic acid or alcohol fermentation, which occur without oxygen.

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Cellular
Respiration!

2. The Essential Questions
How is cellular respiration important to maintain one’s
life?
1) What is cellular respiration?
2) Explain the relationship that occurs between
photosynthesis and cellular respiration.
3) Give the equation for cellular respiration. What are
the reactants and what are the products in this equation?
4)What types of organisms undergo cellular respiration?
5) In what organelle does cellular respiration take place?
6) What types of molecules are broken down through
cellular respiration?
7) What are the products and byproducts of glycolysis?
8) What are the products and byproducts of Krebs
cycle?
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3. More Essentials
9) What are the products and byproducts of ETC?
10) What are the products and byproducts of fermentation?
11) What are some food products that are associated with
lactic acid fermentation and alcoholic fermentation?
12) What is the main purpose of fermentation?
13) Explain why a runner may experience a burning sensation
while running for a long distance.
14) How much ATP is produced in the various steps of cellular
respiration?
15) Explain the difference between aerobic and anaerobic
respiration. What does this mean in terms of efficiency?
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Key Vocabulary
General: (words to apply in many places)
• Oxidize
• Reduce
• Anabolism
• Catabolism
• Phosphorylation
• Mitochondria – outer, inner, intermembrane, matrix
• Cytoplasm - (cytosol)
• Aerobic (Acr)
• Anaerobic (AnCR)

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Key Vocabulary
Energy Molecules
•ADP
•ATP
CoEnzymes
•NAD+
•FAD
•CoA
Carbon Molecules
•Glucose
•G3P
•Pyruvic Acid
Carbon Molecules
•Acetyl acid
•Acetyl-CoA
•Citric Acid
•Oxaloacetate
Enzyme
•ATP synthase
Needed for Respiration
•Oxygen
Waste Products
•Carbon Dioxide
•Water
Fermentation
•lactic acid
• ethanol

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

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BREATHING +
EATING
=
CELL RESPIRATION
Fig. 7.3(bottom)

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Metabolism

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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
to the molecule.
ADP
• Has 2 phosphate groups.
• Lower energy
Glucose
• Has 90x the amount of “potential” energy than ATP
has.
• Cells can use glucose to “charge” ADP to ATP.

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Oxidation and Reduction
• Oxidize – TO LOSE ELECTRONS and LOSE
Hydrogen
– Any molecule containing carbon (1st
3 parts)
• Reduce – TO GAIN ELECTRONS and GAIN
HYDROGEN.
– Electron Carriers: NAD+ and FAD
OIL RIG

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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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Fig. 7.4

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

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Fig. 7.6

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Mitochondria
Outer membrane – encloses
mitochondria, contains protein
channels.
Inner membrane – folds into
CRISTAE that encloses the
MATRIX (the internal fluid of the
mitochondria).
KREBS CYCLE TAKES PLACE
IN THE MATRIX!
ELECTRON TRANSPORT
CHAIN IN THE INNER
MEMBRANE!
Intermembrane Space – used in
the ETC to hold hydrogen ions.

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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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Location of Specific Steps of
Respiration

23. Location of Specific Steps

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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)
– Creates high energy electrons.

25. 25

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Glycolysis
Glycolysis animation

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Glycolysis
• Occurs in CYTOPLASM:
• 2 ATP needed to break GLUCOSE into:
• Two - 3 – CARBON COMPOUNDS – G3P
• ANOTHER REACTION FURTHER “BREAKS
DOWN” the 3C compound (oxidized)
– Removes high energy electrons
– Removes 2 HYDROGEN
• 2NAD+ to 2NADH (electron carrier): REDUCTION
• PHOSPHORYLATES 4 ATP MOLECULES
• Leaves: Two – 3 CARBON COMPOUNDS:
PYRUVATE
• Because of energy released to start Glycolysis:
NET ATP made= 2 molecules

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Fig. 7.7.b

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Glycolysis: Inputs and
Outputs

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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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Oxidative Decarboxylation
Also called:
• Pyruvate Dehydrogenase Complex
• Link Reaction
• Preparatory Reaction

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Oxidative Decarboxylation
A transition step --- in the matrix!
FOR EACH PYRUVATE:
– Each pyruvate loses one carbon (it goes
off as CO2)– A WASTE PRODUCT!
– Pyruvate is converted to a 2-carbon
molecule(2C) = Acetate. (oxidized)
– 2C is picked up by CoA to form Acetyl
CoA – can enter the Krebs Cycle
• NAD+ is reduced to NADH
• NO ATP made

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The Krebs Cycle

34. 34

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The Krebs Cycle the Krebs cycle

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The Krebs Cycle
FOR EACH PYRUVATE:
1. (4C) joins (2C) to form (6C).
1. Co enzyme A leaves reaction
2. 6C is broken down from 6C to 5C to 4C
3. Along the way:
1. 2 more CO2 are released
2. 3 more NAD+ are reduced to NADH
3. 1 FAD is reduced to FADH2
4. 1 ADP is phosphorylated to ATP
4. 4C is recycled.

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Citric Acid Cycle

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Krebs Cycle Totals
For 2 Pyruvates!

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

40. 40

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The Electron Transport Chain
Electron
Transport
System and
ATP Synthesis

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ETC
Inner Membrane of Mitochondria:
1. Electrons from NADH and FADH2 are
passed into the ETC.
2. Electrons are passed from one carrier
protein to the next losing energy.
3. This “lost” energy pumps H+ ions across the
membrane (active transport) creating a +
charge in the intermembrane space and –
charge in the matrix.

43. 43

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ETC
4. “Leftover” electrons combine with
OXYGEN and H+ ions to form water.
– Oxygen is the FINAL ACCEPTOR of
electrons!
THEN:
5. H+ in the intermembrane space
diffuse back into matrix thru ATP
synthase.
6. This process releases energy causing
ADP to phosphorylate into ATP……

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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…

46. j NADH FADH2 ATP from
Electron
Transport
Chain
Direct ATP
from
process
glycolysis
Oxidative
Decarboxylation
Krebs
Cycle

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RESPIRATION
WITHOUT
OXYGEN

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Fig. 7.1

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Without Oxygen:
• Without oxygen, no more NAD+
’s are
generated.
• Without NAD+
’s the Krebs cycle shuts
down.
• Pyruvate cannot convert to Acetyl
CoA
• Does glycolysis continue?
• Yes, but how? …

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52. Lactic Acid Fermentation
• Anaerobic Respiration
• Glycolysis occurs
• 2 net ATP made
• 2 NADH made by reduction
• 2 pyruvate are formed
– THEN in the absence of oxygen:
• 2 NADH are oxidized back into NAD+
• 2 Lactic Acid formed (3-C)
– Use ATP from LA fermentation during quick
exercises only (sprinting). Must repay the
oxygen “debt”
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Alcohol Fermentation
• Anaerobic Respiration
• Glycolysis occurs
• 2 net ATP made
• 2 NADH made by reduction
• 2 pyruvate are formed
THEN in the absence of oxygen
• 2 CO2 are made
• 2 NADH are oxidized back into NAD+
• 2 ethanol are made (2-C molecule
–Yeast – for baking, bacteria - wine making

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Page 126

56. REVIEW
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2

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2 2

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2 2 34

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