Download 2 - The Bronx High School of Science

http://www.youtube.com/watch?v=rVXHYx8zYeI
Overview of cellular respiration
 4 metabolic stages

http://www.youtube.com/watch?v=6JGXayUyNVw
Anaerobic respiration
http://www.youtube.com/watch?v=EfGlznwfu9U
1. Glycolysis
 respiration without O2
 in cytosol

Aerobic respiration
 respiration using O2
 in mitochondria
2. Pyruvate oxidation
3. Krebs cycle
4. Electron transport chain
C H O6 +
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6 12
6O2
 ATP + 6H2O + 6CO2 (+ heat)
Cellular Respiration
http://www.youtube.com/watch?v=VCpNk92uswY
AP Biology
Major Metabolic Pathway
Glucose
Glycolysis
Glc-6-P
Kinase
6
3
Glycogen phosphorylase
Glycogen
Glc-1-P
P
digestion
Starch
Oxidation of Carbon
Mitochondria
Oxidative phosphorylation
P
H
O
P
4 H3-C-H 0
↓
3 H3-C-OH 1 Change
↓
of carbon
2 H2-C=O 1 number
↓
1 H-COOH 2
↓
Pyruvate
0 O=C=O 2
3
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2
Acetyl
CoA A
Pyruvate
ATP
$ $$
Citric
acid
cycle
NADH
H2O
CO2
1
STAGE 3 Energy production
STAGE 2 Unit molecule → Key small molecule
Juang RH (2004) BCbasics
STAGE 1
Macromolecule → Unit molecule
Overview
10 reactions
glucose
C-C-C-C-C-C
2 ATP
2 ADP
convert
fructose-1,6bP
glucose (6C) to
P-C-C-C-C-C-C-P
2 pyruvate (3C)
DHAP
G3P
 produces:
4 ATP & 2 NADH P-C-C-C C-C-C-P
2H
 consumes:
2Pi
2 ATP
 net:
2Pi
2 ATP & 2 NADH

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pyruvate
C-C-C
2 NAD+
2
4 ADP
4 ATP
What’s the
point?
Cellular Respiration
Stages 2 & 3:
Oxidation of Pyruvate
Krebs Cycle
The point
is to make
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ATP!
2013-2014
http://www.youtube.com/watch?v=EfGlznwfu9U
Glycolysis is only the start
 Glycolysis
glucose      pyruvate
6C
2x 3C
 Pyruvate has more energy to yield



3 more C to strip off (to oxidize)
if O2 is available, pyruvate enters mitochondria
enzymes of Krebs cycle complete the full
oxidation of sugar to CO2
pyruvate       CO2
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3C
1C
x3
Cellular respiration
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Mitochondria — Structure
 Double membrane energy harvesting organelle


smooth outer membrane
highly folded inner membrane
 cristae

intermembrane space
 fluid-filled space between membranes

matrix
 inner fluid-filled space


DNA, ribosomes
enzymes
 free in matrix &
What cells would have
AP
Biology
a lot
of mitochondria?
outer
intermembrane
membrane
inner
membrane-bound space
membrane
cristae
matrix
mitochondrial
DNA
Mitochondria – Function
Oooooh!
Form fits
function!
Dividing mitochondria
Membrane-bound proteins
Who else divides like that? Enzymes & permeases
bacteria!
What does this tell us about
the evolution of eukaryotes?
Endosymbiosis!
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Advantage of highly folded inner
membrane?
More surface area for membranebound enzymes & permeases
Oxidation of pyruvate
 Pyruvate enters mitochondrial matrix
[
2x pyruvate    acetyl CoA + CO2
3C
2C
1C
NAD
Where
does the
CO2 go?
Exhale!
3 step oxidation process
 releases 2 CO2 (count the carbons!)
 reduces 2 NAD  2 NADH (moves e )
 produces 2 acetyl CoA


Acetyl CoA enters Krebs cycle
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]
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Pyruvate oxidized to Acetyl CoA
reduction
NAD+
Pyruvate
C-C-C
[
Coenzyme A
CO2
Acetyl CoA
C-C
oxidation
2 x Yield = 2C sugar + NADH + CO2
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]
Pyruvate Oxidation
 2 NADH's are generated
 2 CO2 are released
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Krebs cycle
1937 | 1953
 aka Citric Acid Cycle
in mitochondrial matrix
 8 step pathway

 each catalyzed by specific enzyme
Hans Krebs
1900-1981
 step-wise catabolism of 6C citrate molecule
 Evolved later than glycolysis

does that make evolutionary sense?
 bacteria 3.5 billion years ago (glycolysis)
 free O2 2.7 billion years ago (photosynthesis)
 eukaryotes 1.5 billion years ago (aerobic
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respiration = organelles  mitochondria)
Count the carbons!
pyruvate
3C
2C
6C
4C
This happens
twice for each
glucose
molecule
4C
citrate
oxidation
of sugars
4C
6C
CO2
x2
4C
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acetyl CoA
5C
4C
CO2
http://www.youtube.com/watch?v=hw5nWB0xN0Y&feature=related
http://www.youtube.com/watch?v=p-k0biO1DT8&feature=related
Count the electron carriers!
pyruvate
3C
2C
CO2
acetyl CoA
http://www.youtube.com/watch?v=mFiaIS1IKIA&feature=related
This happens
twice for each
glucose
molecule
6C
4C
NADH
4C
4C
citrate
reduction
of electron
carriers
x2
FADH2
4C ATP
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http://www.youtube.com/watch?v=XG12CMszYLI
NADH
6C
CO2
NADH
5C
4C
CO2
NADH
Figure 9.12-1
Acetyl CoA
CoA-SH
1
Oxaloacetate
Citrate
Citric
acid
cycle
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Figure 9.12-2
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Citrate
Isocitrate
Citric
acid
cycle
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Figure 9.12-3
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Citrate
Isocitrate
NAD
Citric
acid
cycle
3
NADH
+ H
CO2
-Ketoglutarate
AP Biology
Figure 9.12-4
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Citrate
Isocitrate
NAD
Citric
acid
cycle
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
NAD
NADH
Succinyl
CoA
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+ H
CO2
Figure 9.12-5
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Citrate
Isocitrate
NAD
Citric
acid
cycle
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
CoA-SH
5
NAD
Succinate
GTP GDP
ADP
ATP
AP Biology
Pi
Succinyl
CoA
NADH
+ H
CO2
Figure 9.12-6
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Citrate
Isocitrate
NAD
Citric
acid
cycle
Fumarate
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
6
CoA-SH
5
FADH2
NAD
FAD
Succinate
GTP GDP
ADP
ATP
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Pi
Succinyl
CoA
NADH
+ H
CO2
Figure 9.12-7
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Malate
Citrate
Isocitrate
NAD
H2O
Citric
acid
cycle
7
Fumarate
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
6
CoA-SH
5
FADH2
NAD
FAD
Succinate
GTP GDP
ADP
ATP
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Pi
Succinyl
CoA
NADH
+ H
CO2
Figure 9.12-8
Acetyl CoA
CoA-SH
NADH
+ H
H2O
1
NAD
8 Oxaloacetate
2
Malate
Citrate
Isocitrate
NAD
H2O
Citric
acid
cycle
7
Fumarate
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
6
CoA-SH
5
FADH2
NAD
FAD
Succinate
GTP GDP
ADP
ATP
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Pi
Succinyl
CoA
NADH
+ H
CO2
Figure 9.12a
Acetyl CoA
CoA-SH
H2O
1
Oxaloacetate
2
Citrate
Isocitrate
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Figure 9.12b
Isocitrate
NAD
NADH
3
+ H
CO2
CoA-SH
-Ketoglutarate
4
NAD
NADH
Succinyl
CoA
AP Biology
+ H
CO2
Figure 9.12c
Fumarate
6
CoA-SH
5
FADH2
FAD
Succinate
Pi
GTP GDP
ADP
ATP
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Succinyl
CoA
Figure 9.12d
NADH
+ H
NAD
8 Oxaloacetate
Malate
H2O
7
Fumarate
AP Biology
Whassup?
So we fully
oxidized
glucose
C6H12O6

CO2
& ended up
with 4 ATP!
What’s the
point?
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http://www.johnkyrk.com/krebs.html
AP Biology
Electron Carriers = Hydrogen Carriers
H+
 Krebs cycle
produces large
quantities of
electron carriers
NADH
 FADH2
 go to Electron
Transport Chain!

AP Biology
What’s so
important about
electron carriers?
H+
H+
H+
+
H+ H H+
H+
ADP
+ Pi
ATP
H+
Energy accounting of Krebs cycle
4 NAD + 1 FAD
4 NADH + 1 FADH2
2x pyruvate          CO2
3C
3x 1C
1 ADP
1 ATP
ATP
Net gain = 2 ATP
= 8 NADH + 2 FADH2
AP Biology
http://www.youtube.com/watch?v=JPCs5pn7UNI
Value of Krebs cycle?
 If the yield is only 2 ATP, how was the Krebs
cycle an adaptation?

value of NADH & FADH2
 electron carriers & H carriers
 reduced molecules move e-s
 reduced molecules move H+ ions
 to be used in the Electron Transport Chain
like $$
in the
bank
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NADH and FADH2
 So much more to give
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http://www.youtube.com/watch?v=VCpNk92uswY
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
2013-2014
H+
And how do we do that? H
+
H+
H+
H+
H+
H+
H+
 ATP synthase
set up a H+ gradient
 allow H+ to flow
through ATP synthase
 powers bonding
of Pi to ADP

ADP + P
ADP + Pi  ATP
ATP
http://www.youtube.com/watch?v=BGU-g4IYD7c
AP Biology
But…
Have
we done that yet?
http://vcell.ndsu.edu/animations/atpgradient/movie.htm
H+
NO!
The final chapter
to my story is
next!
Any Questions?
AP Biology
2013-2014
Overview – sites of reactions
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FAD Reduction
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Coenzyme A (CoA)
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Pyruvate to acetyl CoA
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