Cellular respiration occurs in three main stages to harvest energy from glucose and produce ATP. Stage 1 is glycolysis in the cytoplasm, which oxidizes glucose to pyruvate and generates 2 ATP and 2 NADH. Stage 2 is the citric acid cycle in the mitochondria, which completes glucose oxidation and generates more NADH and FADH2. Stage 3 is oxidative phosphorylation in the inner mitochondrial membrane, where electrons are transferred through an electron transport chain to generate ATP through chemiosmosis. Fermentation enables some ATP production without oxygen through glycolysis alone.

1. Chapter 6
How Cells Harvest Chemical Energy
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Copyright © 2009 Pearson Education, Inc.
Lecture by Richard L. Myers

2. 6.1 Photosynthesis and cellular respiration provide
energy for life
Energy is necessary EEEnnneeerrrgggyyy iiisss nnneeeccceeessssssaaarrryyy ffffoooorrrr lllliiiiffffeeee pppprrrroooocccceeeesssssssseeeessss
– These include growth, transport,
manufacture, movement, reproduction,
aanndd ootthheerrss
– Energy that supports life on Earth is
captured from sun rays reaching Earth
through plant, algae, protest, and bacterial
photosynthesis
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3. 6.1 Photosynthesis and cellular respiration provide
energy for life
Energy in sunlight is used to make glucose from CO in photosynthesis release of O 2 and H2O with 2
sOOuttghhaeerrr aoorrnggdaa rnneiisslemmasss euu ssCeeO tthhee OO22 aanndd eenneerrggyy iinn 2 and H2O
rTeosgpeotnhseirb, lteh efosre t htwe om parjoocrietys soef sli faer eo n Earth
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4. Sunlight energy
ECOSYSTEM
Photosynthesis
in chloroplasts
Glucose
CO2
+ +
H2O
O2
The connection between
photosynthesis and
cellular respiration
Cellular respiration
in mitochondria
ATP
(for cellular work (ل
Heat energy

5. 6.2 Breathing supplies oxygen to our cells for use in
cellular respiration and removes carbon dioxide
Breathing and cellular respiration are closely
related
–– BBBBBBBBrrrrrrrreeeeeeeeaaaaaaaatttttttthhhhhhhhiiiiiiiinnnnnnnngggggggg iiss nneecceessssaarryy ffoorr eexxcchhaannggee ooff CCOO22 produced during cellular respiration for
atmospheric O2
– CCCCeeeelllllllluuuullllaaaarrrr rrrreeeessssppppiiiirrrraaaattttiiiioooonnnn uses O2 to help harvest
energy from glucose and produces CO2 in the
process
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6. Breathing
CO2 O2
Lungs
CO Bloodstream 2 O2
Muscle cells carrying out
Cellular Respiration
Glucose + O2
CO2 + H2O + ATP
The connection between breathing and cellular respiration

7. INTRODUCTION TO
CELLULAR RESPIRATION
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8. 6.3 Cellular respiration banks energy in ATP molecules
Cellular respiration is an eeeexxxxeeeerrrrggggoooonnnniiiicccc
bprooncdess isn t hgalutc torasnes tfoe rAsT ePnergy from the
– Cellular respiration produces 33338888 AAAATTTTPPPP
mmoolleeccuulleess ffrroomm eeaacchh gglluuccoossee mmoolleeccuullee
– uOstehde ra fso oad sso (uorrcgea noifc e mneorlegcyu ales sw) eclal n be
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9. Summary equation for cellular respiration
C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATPs
Glucose Oxygen Carbon dioxide Water Energy

10. 6.4 CONNECTION: The human body uses energy from
ATP for all its activities
The average adult human needs about
2,200 kcal of energy per day
– A kkkkiiiillllooooccccaaaalllloooorrrriiiieeee (kkkkccccaaaallll) is the quantity of heat
rreeqquuiirreedd ttoo rraaiissee tthhee tteemmppeerraattuurree ooff 11
kilogram (kg) of water by 1oC
– This energy is used for body maintenance
and for voluntary activities
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11. Energy Consumed by Various Activities (in kcal).

12. 6.5 Cells tap energy from electrons “falling” from organic fuels to
oxygen
The energy necessary for life is arrangement of electrons in che mcoicnatal ibnoendd isn itnh e organic molecules
eAnne irmgpy?ortant question is how do cells extract this
Wbrohkeenn t,h eel eccatrrboonns- hayred rtoragnesnf ebrorendd sto o of xgylugceons aen adr e hydrogen – oxygen bonds of water formed.
– eOlxeycgtreonn shas a strong tendency to attract
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13. 6.5 Cells tap energy from electrons “falling” from organic fuels to
oxygen
A cellular respiration equation AAA ccceeelllllluuulllaaarrr rrreeessspppiiirrraaatttiiiooonnn eeeqqquuuaaatttiiiooonnn iiiissss hhhheeeellllppppffffuuuullll ttttoooo
sssshhhhoooowwww tttthhhheeee cccchhhhaaaannnnggggeeeessss iiiinnnn hhhhyyyyddddrrrrooooggggeeeennnn aaaattttoooommmm
ddddiiiissssttttrrrriiiibbbbuuuuttttiiiioooonnnn
–– GGlluuccoossee lloosseess iittss hhyyddrrooggeenn aattoommss aanndd iiss uullttiimmaatteellyy
converted to CO2
– At the same time, O2 gains hydrogen atoms and is
converted to H2O
– Loss of electrons is called ooooxxxxiiiiddddaaaattttiiiioooonnnn
– Gain of electrons is called rrrreeeedddduuuuccccttttiiiioooonnnn
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14. Loss of hydrogen atoms
C6H12O6 + 6 O2
6 CO2 + 6 H2O + Energy
(ATP)
Rearrangement of hydrogen atoms (with their electrons)
in the redox reactions of cellular respiration
(Oxidation)
Glucose
Gain of hydrogen atoms
(Reduction)
A cellular respiration AAA ccceeelllllluuulllaaarrr rrreeessspppiiirrraaatttiiiooonnn eeeeqqqquuuuaaaattttiiiioooonnnn

15. 6.5 Cells tap energy from electrons “falling” from organic fuels to
oxygen
Enzymes are necessary to oxidize other foods glucose and
– oTrhgea ennicz mymoele cthualet ries mcaolvleeds ddddheeeeyhhhhdyyyyroddddgrrrrooooeggggneeee fnnnnroaaaamsssseeee an
–– DDNNNNeeAAAAhhDDDDyy+dd(rrnooiggceeonntinaaasseem rrideeeqq uuaiidrreeessn iaan ecc oodeeinnnuzzcyylmmeoeet iccdaaell)llee tddo shuttle electrons
– eNlAecDt+rocnasn a bnedc oomxidei zreeddu wcheedn w iht egniv eits a tchceemp tsu p
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16. pair of redox reactions, occurring simultaneously
Oxidation
Dehydrogenase
aaaaddddeeeennnniiiinnnneeee ddddiiiinnnnuuuucccclllleeeeoooottttiiiiddddeeee
Reduction زال ا
NAD+ + 2 H NADH + H+
2 H+ + 2 e–
(carries
2 electrons)

17. 6.5 Cells tap energy from electrons “falling” from organic fuels to
oxygen
The transfer of electrons to NAD+
results in the formation of NADH,
the reduced form of NAD+
– In this situation, NAD+ is acceptor, but it eventuall yc ablelecdo mane se lectron coaxlildeizde adn ( elolesectsr oann deolencotrron) and is then
Copyright © 2009 Pearson Education, Inc.

18. 6.5 Cells tap energy from electrons “falling” from organic fuels to
oxygen
There are other electron “carrier” molecules
that function like NAD+ .called FAD
– They form a staircase where the electrons
pass from one to tthhee nneexxtt ddoowwnn tthhee
staircase
– These electron carriers collectively are
called the eeeelllleeeeccccttttrrrroooonnnn ttttrrrraaaannnnssssppppoooorrrrtttt cccchhhhaaaaiiiinnnn, and as
electrons are transported down the chain,
ATP is generated
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19. NADH
NAD+ ATP
H+
2e–
Controlled
release of
energy for
synthesis
of ATP
+
H+
2e–
O2
H2O
1-
In cellular respiration, electrons fall 2
down an energy staircase and finally
reduce O2

20. STAGES OF CELLULAR
RESPIRATION
AND FERMENTATION
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21. 6.6 Overview: Cellular respiration occurs in three main stages
SSSSttttaaaaggggeeee 1:::: GGGGllllyyyyccccoooollllyyyyssssiiiissss
SSSSttttaaaaggggeeee 2:::: TTTThhhheeee cccciiiittttrrrriiiicccc aaaacccciiiidddd ccccyyyycccclllleeee
SSSSttttaaaaggggeeee 3:::: OOOOxxxxiiiiddddaaaattttiiiivvvveeee pppphhhhoooosssspppphhhhoooorrrryyyyllllaaaattttiiiioooonnnn
Copyright © 2009 Pearson Education, Inc.

22. 6.6 Overview: Cellular respiration occurs in three main stages
SSSSttttaaaaggggeeee 1:::: GGGGllllyyyyccccoooollllyyyyssssiiiissss
– rGelsypcioralytsioisn bbeyg binresa king gmluocleocsuele, a, i nsitxo- ctwaorb on
Glucose
C-C-C-C-C-C
Glycolysis
In Cytoplasm
mmoolleeccuullee,s ionft oa t wthore e- cpayrrubvoant ecompound called
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C-C-C C-C-C
Pyruvate Pyruvate

23. Glucose
NAD+
+
2
2 ADP
2 NADH
2 P
6.7 Glycolysis harvests chemical energy
by oxidizing glucose to pyruvate
Ionf ggllyuccoolsyes iiss, ean sziynmglaet imcaollleyc cuulet in hpraolfd tuhcroeu twgho am soelericeusl eosf sotfe ps to pyruvate
2 ATP +
2
H+
2 Pyruvate
An overview of glycolysis
– Ionf tNhAeD p+roacrees rse,d tuwcoe dm otole tcwuole s molecules of NADH
– Amto tlheec uslaems eo ft iAmTeP, tawreo pprhoodsupcheodr yblayt isounbstrate-level

24. 6.6 Overview: Cellular respiration occurs in three main stages
SSSSttttaaaaggggeeee 2:::: TTTThhhheeee cccciiiittttrrrriiiicccc aaaacccciiiidddd ccccyyyycccclllleeee
- The citric acid cycle completes the oxidation of organic
molecules supplies the third stage with electrons
generating many NADH and FADH2
-It breaks down pyruvate into carbon dioxide
--TThhiiss ssttaaggee ooccccuurrss iinn tthhee mmiittoocchhoonnddrriiaa..--
Pyruvate Electrons
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Citric Acid
Cycle
CO2

25. 6.6 Overview: Cellular respiration occurs in three main stages
SSSSttttaaaaggggeeee 3:::: OOOOxxxxiiiiddddaaaattttiiiivvvveeee pppphhhhoooosssspppphhhhoooorrrryyyyllllaaaattttiiiioooonnnn
– At this stage, electrons are shuttled through the electron transport chain
– As a result, ATP is generated through oxidative phosphorylation
associated with chemiosmosis
– This stage occurs in the inner mitochondrion membrane
Pyruvate
Citric Acid
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Cycle
CO2
Electrons
O2
Electron Transport Chain
Oxidative
Phosphorylation
H2O ATP
Mitochondria
Chemiosmosis

26. An overview of cellular respiration
NADH Mitochondrion
High-energy electrons
carried by NADH
NADH
CITRIC ACID
CYCLE
GLYCOLYSIS
Glucose Pyruvate
and
FADH2
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
CO2 CO2
ATP
Substrate-level phosphorylation Substrate-level phosphorylation
Oxidative phosphorylation
ATP
ATP
Cytoplasm
Inner mitochondrial
Membrane

27. 6.13 Fermentation enables cells to produce ATP without
oxygen
FFFFeeeerrrrmmmmeeeennnnttttaaaattttiiiioooonnnn is an anaerobic (without oxygen)
energy-generating process
– It takes advantage of glycolysis, pppprrrroooodddduuuucccciiiinnnngggg ttttwwwwoooo
AAAAAAAATTTTTTTTPPPPPPPP mmoolleeccuulleess aanndd rreedduucciinngg NNAADD++ ttoo NNAADDHH
– The trick is to oxidize the NADH without passing
its electrons through the electron transport chain
to oxygen
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28. 6.13 Fermentation enables cells to produce ATP without
oxygen
ن و ا
ا دون ا ATP ج ا

29. درة ر ا ل ا
Your muscle cells and certain bacteria
can oxidize NADH through llllaaaaccccttttiiiicccc aaaacccciiiidddd
ffffeeeerrrrmmmmeeeennnnttttaaaattttiiiioooonnnn
NADH is oxidized to NAD+ when pyruvate is
reduced to lactate
In a sense, pyruvate is serving as an “electron
sink,” a place to dispose of the electrons
generated by oxidation reactions in glycolysis
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30. Glucose وز و
NAD+
NADH
GLYCOLYSIS وزي و ل
2 ADP 2
2
P
2 ATP
2 Pyruvate ت رو 2
Lactic acid fermentation
ض ا ر ا
+ 2
2 NADH
2 NAD+
2 Lactate ت$ 2

31. 6.13 Fermentation enables cells to produce ATP without
oxygen
The baking and winemaking
industry have used aaaallllccccoooohhhhoooollll
ffffeeeerrrrmmmmeeeennnnttttaaaattttiiiioooonnnn for thousands of years
rYeesapsirtas taiorne fsoinr gelnee-crgeyll ebdu tf ucnagni ftehramt neontt ounnldye cr an use anaerobic conditions
oTxhiedyiz cinogn vNeArtD pHy rbuavcakte t oto N CAOD2 and ethanol while +
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32. 2 ADP
P
2 ATP
Glucose
GLYCOLYSIS
NAD+
NADH
2
2
2 Pyruvate
+ 2
2 NADH
2 NAD+
2 Ethanol
Alcohol fermentation 2 CO2
Released

33. INTERCONNECTIONS BETWEEN
MOLECULAR BREAKDOWN
AND SYNTHESIS
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34. 6.15 Cells use many kinds of organic molecules as fuel
for cellular respiration
% وا س ا ( ود و و) ت ا ر ن ا د د ا دم ا
Although glucose is considered to be the primary source of
sugar for respiration and fermentation, there are actually three
sources of molecules for generation of ATP
–CCCCaaaarrrrbbbboooohhhhyyyyddddrrrraaaatttteeeessss (disaccharides)
–PPPPrrrrooootttteeeeiiiinnnnssss (after conversion to amino acids)
–FFFFaaaattttssss
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35. Food, such as
peanuts
Carbohydrates Fats Proteins
Sugars Glycerol Fatty acids Amino acids ض ا أ
Amino groups
Glucose
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
CITRIC ACID
CYCLE
Acetyl CoA
Pyruvate
G3P
GLYCOLYSIS
ATP
Pathways that break down various food molecules