Cellular Respiration

Types of respiration

1. ZOOLOGYZOOLOGY
Cellular RespirationCellular Respiration
By-
Dr. Dinesh C. Sharma,
Head, Zoology
Govt. P. G. College, Noida

2. ZOOLOGY
What is Cellular Respiration?What is Cellular Respiration?
The process of converting food energy The process of converting food energy
into ATP energyinto ATP energy
CC
66HH
1212OO
66 + 6 O + 6 O
22 → → 6 CO6 CO
22 + 6 H + 6 H
22O + 36 ATPO + 36 ATP

3. ZOOLOGY
Why are both Photosynthesis and Cell Why are both Photosynthesis and Cell
Respiration important to Ecosystems?Respiration important to Ecosystems?
Light is the ultimate Light is the ultimate
source of energy for all source of energy for all
ecosystemsecosystems
Chemicals cycle and Chemicals cycle and
Energy flowsEnergy flows
Photosynthesis and Photosynthesis and
cellular respiration are cellular respiration are
opposite reactionsopposite reactions

4. ZOOLOGY
Why do plants need both Why do plants need both
chloroplasts and mitochondria?chloroplasts and mitochondria?
Chloroplasts use Chloroplasts use
energy from the energy from the
sun to make sun to make
glucoseglucose
Mitochondria Mitochondria
convert glucose to convert glucose to
ATP—the energy ATP—the energy
currency of the cellcurrency of the cell

5. ZOOLOGY
What is ATP?What is ATP?
Adenosine TriphosphateAdenosine Triphosphate
–5-Carbon sugar (Ribose)5-Carbon sugar (Ribose)
– Nitrogenous base Nitrogenous base
(Adenine)(Adenine)
–3 Phosphate groups3 Phosphate groups
Energy currency of the Energy currency of the
cellcell
The chemical bonds that The chemical bonds that
link the phosphate groups link the phosphate groups
together are high energy together are high energy
bondsbonds
When a phosphate group When a phosphate group
is removed to form ADP is removed to form ADP
and P, small packets of and P, small packets of
energy are releasedenergy are released

6. ZOOLOGY
How is ATP used?How is ATP used?
As ATP is broken down, it As ATP is broken down, it
gives off usable energy to gives off usable energy to
power chemical work and power chemical work and
gives off some nonusable gives off some nonusable
energy as heat.energy as heat.
Synthesizing molecules for Synthesizing molecules for
growth and reproductiongrowth and reproduction
Transport work – active Transport work – active
transport, endocytosis, and transport, endocytosis, and
exocytosisexocytosis
Mechanical work – muscle Mechanical work – muscle
contraction, cilia and flagella contraction, cilia and flagella
movement, organelle movement, organelle
movementmovement

7. ZOOLOGY
Why use ATP energy and not Why use ATP energy and not
energy from glucose?energy from glucose?
Breaking down glucose yields too much energy Breaking down glucose yields too much energy
for cellular reactions and most of the energy for cellular reactions and most of the energy
would be wasted as heat.would be wasted as heat.
1 Glucose = 686 kcal1 Glucose = 686 kcal
1 ATP = 7.3 kcal1 ATP = 7.3 kcal
1 Glucose 1 Glucose → → 36 ATP36 ATP
How efficient are cells at converting glucose into How efficient are cells at converting glucose into
ATP?ATP?
–38% of the energy from glucose yields ATP, 38% of the energy from glucose yields ATP,
therefore 62% wasted as heat.therefore 62% wasted as heat.

8. ZOOLOGY
Cellular Respiration is a Redox ReactionCellular Respiration is a Redox Reaction

CC
66HH
1212OO
66 + 6 O + 6 O
22 → 6 CO→ 6 CO
22 + 6 H + 6 H
22OO
OxidationOxidation is the loss of electrons or H is the loss of electrons or H
++
ReductionReduction is the gain of electrons or H is the gain of electrons or H
++
Glucose is oxidized when electrons and HGlucose is oxidized when electrons and H
++
are passed are passed
to coenzymes NADto coenzymes NAD
++
and FAD before reducing or and FAD before reducing or
passing them to oxygen.passing them to oxygen.
Glucose is oxidized by a Glucose is oxidized by a series of smaller stepsseries of smaller steps so so
that smaller packets of energy are released to make that smaller packets of energy are released to make
ATP, rather than one large explosion of energy.ATP, rather than one large explosion of energy.
(Oxidation)
(Reduction)

9. ZOOLOGY
Cell Respiration can be divided into 4 Parts:Cell Respiration can be divided into 4 Parts:
1) Glycolysis1) Glycolysis
2) Oxidation of Pyruvate / Transition Reaction2) Oxidation of Pyruvate / Transition Reaction
3) The Krebs Cycle3) The Krebs Cycle
4) The Electron Transport Chain and 4) The Electron Transport Chain and
Chemiosmotic PhosphorylationChemiosmotic Phosphorylation

10. ZOOLOGY
Where do the 4 parts of Cellular Where do the 4 parts of Cellular
Respiration take place?Respiration take place?
Glycolysis: Glycolysis:
–CytosolCytosol
Oxidation of Oxidation of
Pyruvate:Pyruvate:
–MatrixMatrix
The Krebs Cycled:The Krebs Cycled:
–MatrixMatrix
Electron Transport Electron Transport
Chain and Chain and
Cheimiosmotic Cheimiosmotic
Phosphorylation:Phosphorylation:
–CristaeCristae

11. ZOOLOGY
Parts of the MitochondriaParts of the Mitochondria

12. ZOOLOGY
Anaerobic Respiration (no oxygen required, cytoplasm)Anaerobic Respiration (no oxygen required, cytoplasm)
1.Glycolysis
(substrate level)
Glucose  2 Pyruvate
2 ATP 4 ATP (Net 2 ATP)
2 NADH
Aerobic Respiration (oxygen required, mitochondria)Aerobic Respiration (oxygen required, mitochondria)
2. Oxidation
of
Pyruvate
2 Pyruvate  2 CO
2
2 NADH
2 Acetyl CoA
3.Krebs Cycle
(substrate level)
2 Acetyl CoA  4 CO
2
2 ATP
6 NADH
2 FADH
2
4.Electron
Transport
Chain
(chemiosmotic)
10 NADH  32 ATP
2 FADH
2
H
2
O
Oxygen
Total: 36 ATP produced

13. ZOOLOGY
ATP is made in two ways:ATP is made in two ways:
1) 1) Substrate Level Substrate Level
PhosphorylationPhosphorylation (glycolysis (glycolysis
& Krebs cycle)& Krebs cycle)
2) 2) Chemiosmotic Chemiosmotic
PhosphorylationPhosphorylation (electron (electron
transport chain)transport chain)
Substrate-Level Substrate-Level
Phosphorylation:Phosphorylation:
Energy and phosphate are Energy and phosphate are
transferred to ADP using an transferred to ADP using an
enzyme, to form ATP. enzyme, to form ATP.
Phosphate comes from one Phosphate comes from one
of the intermediate of the intermediate
molecules produced from molecules produced from
the breakdown of glucose.the breakdown of glucose.

14. ZOOLOGY
GlycolysisGlycolysis
Glucose (CGlucose (C
66) is split to make ) is split to make
2 Pyruvates (C2 Pyruvates (C
33))
–11
stst
: ATP energy used to phosphorylate : ATP energy used to phosphorylate
glucose (stored energy)glucose (stored energy)
–22
ndnd
: phosphorylated glucose broken : phosphorylated glucose broken
down into two Cdown into two C
33 sugar phosphates sugar phosphates
–33
rdrd
: the sugar phosphates are oxidized : the sugar phosphates are oxidized
to yield electrons and Hto yield electrons and H
++
ions which are ions which are
donated to 2 NADdonated to 2 NAD
++
→ → 2 NADH (stored 2 NADH (stored
electron and hydrogen for the Electron electron and hydrogen for the Electron
Transport Chain)Transport Chain)
–44
thth
: The energy from oxidation is used to : The energy from oxidation is used to
make 4 ATP molecules (net 2 ATP)make 4 ATP molecules (net 2 ATP)
This is substrate level phosphorylation This is substrate level phosphorylation
because an enzyme transfers because an enzyme transfers
phosphate to ADP making ATPphosphate to ADP making ATP
Glycolysis produces very little ATP Glycolysis produces very little ATP
energy, most energy is still stored in energy, most energy is still stored in
Pyruvate molecules.Pyruvate molecules.
Glucose  2 Pyruvate
2 ATP 4 ATP (Net 2 ATP)
2 NADH

15. ZOOLOGY
Oxidation of Pyruvate /Transition ReactionOxidation of Pyruvate /Transition Reaction
When Oxygen is present,
2 Pyruvates go to the
matrix where they are
converted into 2 Acetyl
CoA (C
2
).
Multienzyme complex:
–1
st:
each Pyruvate releases
CO
2
to form Acetate.
–2
nd:
Acetate is oxidized and
gives electrons and H
+
ions
to 2 NAD
+
→ 2 NADH.
–3
rd
Acetate is combined with
Coenzyme A to produce 2
Acetyl CoA molecules.
2 NADH’s carry electrons
and hydrogens to the
Electron Transport Chain.
2 Pyruvate  2 CO
2
2 NADH
2 Acetyl CoA

16. ZOOLOGY
The Krebs Cycle / Citric Acid CycleThe Krebs Cycle / Citric Acid Cycle
8 Enzymatic Steps in Matrix of
Mitochondria: Break down and Oxidize
each Acetyl CoA (2-C’s) to release 2 CO
2

and yield electrons and H
+
ions to
3 NAD
+
+ 1 FAD → 3 NADH + FADH
2
.
This yields energy to produce ATP by
substrate level phosphorylation.
The first step of the Krebs cycle combines
Oxaloacetate (4 C’s) with Acetyl CoA to
form Citric Acid, then the remaining 7
steps ultimately recycle oxalacetate.
Two Turns of the Krebs Cycle are required
to break down both Acetyl Coenzyme A
molecules.
The Krebs cycle produces some chemical
energy in the form of ATP but most of
the chemical energy is in the form of
NADH and FADH
2
which then go on to
the Electron Transport Chain.
2 Acetyl CoA  4 CO
2
2 ATP
6 NADH
2 FADH
2

17. ZOOLOGY
The Electron Transport ChainThe Electron Transport Chain
NADH and FADHNADH and FADH
22 produced produced
earlier, go to the Electron earlier, go to the Electron
Transport Chain.Transport Chain.
NADH and FADHNADH and FADH
22 release release
electrons to carriers/proteins electrons to carriers/proteins
embedded in the membrane embedded in the membrane
of the cristae. As the of the cristae. As the
electrons are transferred, Helectrons are transferred, H
++

ions are pumped from the ions are pumped from the
matrix to the intermembrane matrix to the intermembrane
space up the concentration space up the concentration
gradient. Electrons are gradient. Electrons are
passed along a series of 9 passed along a series of 9
carriers until they are carriers until they are
ultimately donated to an ultimately donated to an
Oxygen molecule. Oxygen molecule.
½ O½ O
22 + 2 electrons + 2 H + 2 electrons + 2 H
++

(from NADH and FADH(from NADH and FADH
22) ) → →
HH
22O. O.
10 NADH  32 ATP
2 FADH
2
H
2
O
Oxygen
http://vcell.ndsu.nodak.edu/animations/etc/movie.htm

18. ZOOLOGY
Chemiosmotic PhosphorylationChemiosmotic Phosphorylation
Hydrogen ions travel down their concentration gradient through a channel Hydrogen ions travel down their concentration gradient through a channel
protein coupled with an enzyme called protein coupled with an enzyme called ATP SynthaseATP Synthase..
As HAs H
++
ions move into the matrix, energy is released and used to combine ions move into the matrix, energy is released and used to combine
ADP + P ADP + P → → ATP.ATP.
Hydrogens are recycled and pumped back across the cristae using the Hydrogens are recycled and pumped back across the cristae using the
Electron Transport Chain.Electron Transport Chain.
ATP diffuses out of the mitochondria through channel proteins to be used ATP diffuses out of the mitochondria through channel proteins to be used
by the cell.by the cell.
http://vcell.ndsu.nodak.edu/animations/atpgradient/movie.htm

19. ZOOLOGY
ATP SynthaseATP Synthase
Multisubunit complex Multisubunit complex
with 4 parts:with 4 parts:
–RotorRotor – spins as H – spins as H
++
ions flow ions flow
–StatorStator – holds the rotor and – holds the rotor and
knob complex together in the knob complex together in the
cristaecristae
–Internal RodInternal Rod – extends – extends
between rotor and knob, spins between rotor and knob, spins
when rotor spins which then when rotor spins which then
turns the knobturns the knob
–KnobKnob – contains 3 catalytic – contains 3 catalytic
sites that when turned change sites that when turned change
shape and activate the enzyme shape and activate the enzyme
used to make ATPused to make ATP

20. ZOOLOGY
Review ATP Production:Review ATP Production:
1) Glycolysis 1) Glycolysis → → 2 ATP2 ATP
2) Oxidation of Pyruvate 2) Oxidation of Pyruvate → → No ATPNo ATP
3) The Krebs Cycle 3) The Krebs Cycle → → 2 ATP2 ATP
4) The Electron Transport Chain and 4) The Electron Transport Chain and
Chemiosmotic Phosphorylation: Chemiosmotic Phosphorylation:
–Each NADH produces 2-3 ATP so Each NADH produces 2-3 ATP so
10 NADH 10 NADH →→ 28 ATP 28 ATP
–Each FADHEach FADH
22 produces 2 ATP so 2 produces 2 ATP so 2
FADHFADH
22 → → 4 ATP4 ATP
Total = 36 ATPTotal = 36 ATP
1 Glucose = 686 kcal1 Glucose = 686 kcal
1 ATP = 7.3 kcal1 ATP = 7.3 kcal
1 Glucose 1 Glucose → → 36 ATP36 ATP
How efficient are cells at converting How efficient are cells at converting
glucose into ATP?glucose into ATP?
–38% of the energy from glucose 38% of the energy from glucose
yields ATP, therefore 62% wasted as yields ATP, therefore 62% wasted as
heat (used to maintain body heat (used to maintain body
temperature or is dissipated)temperature or is dissipated)
–Ex. Most efficient Cars: only 25% of Ex. Most efficient Cars: only 25% of
the energy from gasoline is used to the energy from gasoline is used to
move the car, 75% heat.move the car, 75% heat.

21. ZOOLOGY
All Types of Molecules can be used All Types of Molecules can be used
to form ATP by Cell Respiration: to form ATP by Cell Respiration:
Proteins, Carbohydrates, Proteins, Carbohydrates,
and Lipids must first be and Lipids must first be
broken down into their broken down into their
monomers and absorbed monomers and absorbed
in the small intestine.in the small intestine.
Monomers may be Monomers may be
further broken down into further broken down into
intermediate molecules intermediate molecules
before entering different before entering different
parts of Cell respiration parts of Cell respiration
to ultimately form ATP.to ultimately form ATP.

22. ZOOLOGY
Anaerobic Respiration: FermentationAnaerobic Respiration: Fermentation
If there is NO oxygen, then cells can make ATP by If there is NO oxygen, then cells can make ATP by FermentationFermentation
Without oxygen, Oxidation of Pyruvate and the Electron Without oxygen, Oxidation of Pyruvate and the Electron
Transport Chain do not operate.Transport Chain do not operate.
Glucose Glucose →→ Pyruvate Pyruvate →→ Lactate Lactate
NADNAD
++
GlycolysisGlycolysis 2 NADH 2 NADH Reduction RxnReduction Rxn or or
2 ATP 2 ATP Alcohol + CO Alcohol + CO
22
Fermentation yields a net gain of 2 ATP by substrate level phosphorylation Fermentation yields a net gain of 2 ATP by substrate level phosphorylation
for every 1 Glucose. (Inefficient)for every 1 Glucose. (Inefficient)
Two Forms of FermentationTwo Forms of Fermentation: :
Lactic Acid Fermentation (animals)Lactic Acid Fermentation (animals)
Alcohol Fermentation (yeast)Alcohol Fermentation (yeast)