key themes (2) “think like a biologist”: understand what life is. “unity” of life: what are...
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Key Themes
(2) “Think Like a Biologist”: Understand What Life Is.“Unity” of life: What are common features of eukaryotes?
Energy conversions: Sugar breakdown & mitochondrial ATP formation
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Lecture 7: Cellular Respiration
Yesterday’s Exit Ticket– Energy-releasing reactions:
• Large, complex smaller, simpler• Release energy and increase entropy
• e.g. ATP ADP and Pi
• e.g. respiration (glucose + O2 H2O + CO2 + ATP)
– Energy-requiring reactions:• Smaller, simpler large complex• Decrease entropy• e.g. ADP + Pi ATP
• e.g. photosynthesis (light E + H2O + CO2 glucose + O2)
Cellular respiration breaks down energy-rich molecules to CO2 & water, extracting their energy.
Fig. 9.2
Lightenergy
ECOSYSTEM
Photosynthesisin chloroplasts
CO2 + H2OCellular respiration
in mitochondria
Organicmolecules+ O2
ATP powers most cellular work
Heatenergy
ATP
High energy
Low energy
C-H bond
“burned” with O2
to H2O + CO2
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Photosynthesis:
Respiration:
ATP
Since ATP is too unstable,
C-H bonds in sugars are used for energy storage.
Converts solar energy
to ATP and uses ATP to make sugars
Converts the energy of sugars back to ATP as needed.
Sugar [CH2O]x + O2CO2 + H20
ATPLight (energy)
H+ & e-
H+ & e-
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What is the goal of cellular respiration?
• Food ATP• Release the energy in C-H bonds• Harness that energy to create ATP
6-C sugar
Glucose + O2
(6-C sugar) ATP + CO2 + H20(energy)
3-C sugars+ some ATP
CO2
+ some ATPH2O + ATP
H+ & e-
O2
H+ & e-
paraibaparadise.com
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What is the goal of cellular respiration?
6-C sugar3-C sugars
+ some ATPCO2
+ some ATPH2O + ATP
H+ & e-
O2
H+ & e-
Step 1: Glycolysis
Step 2: Citric Acid
Cycle
Step 3: Oxidative
Phosphorylation
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Step 1: Glycolysis•Occurs in: cytosol•Starts with: glucose, NAD+, ADP, Pi
•Produces: pyruvate, NADH, and ATP
Glucose (6-C sugar)
Pyruvates(3-C sugars)+ some ATP
H+ & e-
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Cytosol
Fig. 9.6
Glucose Pyruvate
Glycolysis
Electronscarried off by NADH
ATPSome
Step 1: Glycolysis•Occurs in: cytosol•Starts with: glucose, NAD+, ADP, Pi
•Produces: pyruvate, NADH, and ATP
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Pyruvates(3-C sugars)+ some ATP
Glucose (6-C sugar)
Step 1: Glycolysis•Occurs in: cytosol•Starts with: glucose, NAD+, ADP, Pi
•Produces: pyruvate, NADH, and ATP
H+ & e-
NAD+
NADH
Glycolysis can occur with or without O2!!
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Pyruvates(3-C sugars)+ some ATP
CO2
+ some ATPH+ & e-
Step 2: Citric Acid Cycle•Occurs in: mitochondrial matrix (fluid space)•Starts with: pyruvate, NAD+, FAD, ADP, Pi
•Produces: NADH, FADH2, CO2 and ATP
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Fig. 9.6
Mitochondrion
Electrons carried off by
NADH & FADH2
Citricacidcycle
ATP
Glucose Pyruvate
Glycolysis
Electronscarried off by NADH
Some ATPSome
Cytosol
Step 2: Citric Acid Cycle•Occurs in: mitochondrial matrix (fluid space)•Starts with: pyruvate, NAD+, FAD, ADP, Pi
•Produces: NADH, FADH2, CO2 and ATP
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CO2
+ some ATPH+ & e-
Step 2: Citric Acid Cycle•Occurs in: mitochondrial matrix (fluid space)•Starts with: pyruvate, NAD+, FAD, ADP, Pi
•Produces: NADH, FADH2, CO2 and ATP
NAD+
FAD
NADHFADH2
Pyruvates(3-C sugars)+ some ATP
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Step 3: Oxidative Phosphorylation(Using oxygen to phosphorylate ADP)
•Occurs in: mitochondrial inner membranes•Starts with: O2, NADH, FADH2, ADP, Pi
•Produces: H2O, ATP, NAD+, FAD
H2O + ATP
NADH
O2
NADHFADH2
ADPPi
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Electrontransport
andATP synthase
Mitochondrion
ATP
Electrons carried off by
NADH & FADH2
Citricacidcycle
ATP
Glucose Pyruvate
Glycolysis
Electronscarried off by NADH
Fig. 9.6
Some Some ATPLots of
Cytosol
Step 3: Oxidative Phosphorylation(Using oxygen to phosphorylate ADP)
•Occurs in: mitochondrial inner membranes•Starts with: O2, NADH, FADH2, ADP, Pi
•Produces: H2O, ATP, NAD+, FAD
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H (electrons and H+) removed from high energy C-H bonds
CO2
+ some ATPH2O + ATP
H+ & e- (via NADH)
O2
Pyruvates(3-C sugars)+ some ATP
Glucose (6-C sugar)
H+ & e- (via NADH & FADH2)
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I
H - C - OH (CHOH)6 (= C6H12O6 sugar)
I
to
O = C = O CO2
Where does H go?H (electrons and H+) are loaded onto
electron carriers NADH & FADH2
H (electrons and H+) removed from high energy C-H bonds
(all the way to CO2 in the citric acid cycle)
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H (electrons and H+) removed from high energy C-H bonds
CO2
+ some ATPH2O + ATP
H+ & e- (via NADH)
O2
Pyruvates(3-C sugars)+ some ATP
Glucose (6-C sugar)
H+ & e- (via NADH & FADH2)
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ATP
Mitochondrion
ATP
Electrons carried off by
NADH & FADH2
Citricacidcycle
ATP
Cytosol
Glucose Pyruvate
Glycolysis
Electronscarried off by NADH
Fig. 9.6
2 2 ~34
Most ATP is formed by electron transport chainthrough oxidative phosphorylation
Electrontransport
andATP synthase
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Smooth outer membrane
Folded inner membrane:
Matrix:Citric acid cycle
Mitochondria
Electron transport chain & ATP formation
Fig. 6.17
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Protein complexof electroncarriers
H+
H+H+
Cyt c
Q
V
FADH2 FAD
NAD+NADH(carrying electronsfrom food)
Electron transport chain & pumping of protons
2 H+ + 1/2O2 H2O
ADP +Pi
H+
H+
ATP synthase
ATP
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The electron transport chain pumps protons against the concentration gradient; builds up a high H+ concentration in intermembrane space.
Intermembranespace
Mitochondrial matrix
Innermembrane
Fig. 9.16
ATP synthesis via H+ flow
Step 3: Oxidative Phosphorylation
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Protein complexof electroncarriers
H+
H+H+
Cyt c
Q
V
FADH2 FAD
NAD+NADH(carrying electronsfrom food)
Electron transport chain & pumping of protons
2 H+ + 1/2O2 H2O
ADP +Pi
H+
H+
ATP
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Intermembranespace
Mitochondrial matrix
Innermembrane
Fig. 9.16
ATP synthesis via H+ flow
INTERMEMBRANE SPACE
RotorH+ Stator
Internalrod
Cata-lyticknob
ADP+
P ATPi
MITOCHONDRIAL MATRIX
Fig. 9.14Oxygen (O2) is the final electron (and H+) acceptor
ATP synthase
Protons flow downhill through the ATP synthase, driving phosphorylation of ADP to ATP.
Step 3: Oxidative Phosphorylation
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Let’s take a look at the whole sequence: • Step 1: Glycolysis• Step 2: Citric Acid Cycle • Step 3: Oxidative Phosphorylation
http://www.colorado.edu/ebio/genbio/09_15ElectronTransport_A.html
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Electron Donors and Electron Acceptors
CO2
+ some ATPH2O + ATP
H+ & e- (via NADH)
O2
Pyruvates(3-C sugars)+ some ATP
Glucose (6-C sugar)
H+ & e- (via NADH & FADH2)
Original electron donor in cellular respiration
Electron donors for mitochondrial
electron transport chain
Electron acceptor from mitochondrial
electron transport chain
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ATP links the energy from breakdown of energy-rich food molecules to cellular work
P iADP+
Energy frombreakdown ofenergy-rich molecules
Energy for cellularwork
ATP + H2OEnergy loaded onto
ATPEnergy released from
ATP
Fig. 8.12
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Proteins
Proteins Carbohydrates
Aminoacids
Sugars
Fats
Glycerol Fattyacids
Glycolysis
Glucose
Glyceraldehyde-3-
Pyruvate
P
NH3
Acetyl CoA
Citricacidcycle
Oxidativephosphorylation
Fig. 9.20
The cellular respiration pathway for
Carbohydrates
Fats
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Predict how the enzymes that function early in glycolysis, and start the breakdown of glucose, should be regulated: The enzymes should
A) not be regulated.B) be turned off when enough (ATP) energy is available.C) be turned on when more (ATP) energy is needed.D) be regulated in a dual way, both by activation when more ATP energy is needed and by inactivation when enough ATP energy is available.
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Glucose
Glycolysis
PyruvateCYTOSOL
MITOCHONDRION
Fig. 9.19
• Step 1 of cellular respiration:
Glycolysisoutside
mitochondria
From glucose (6 C) to 2
pyruvate (3 C)Citricacidcycle
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Glucose
Glycolysis
PyruvateCYTOSOL
O2 present:
Aerobic cellular respiration
MITOCHONDRION
Acetyl CoA
Citricacidcycle
Fig. 9.19
•Only when oxygen is present
can glucosebe broken
down completely
in the mitochondria
for high energy yield
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Glucose
Glycolysis
PyruvateCYTOSOL
No O2 present:Fermentation
MITOCHONDRION
Acetyl CoAEthanolor
lactateCitricacidcycle
Fig. 9.19 34
Alcoholic fermentation (forms ethanol plus CO2) by yeasts and bacteria under anaerobic conditions
Glycolysis & fermentation
2 ADP + 2 P i 2 ATP
Glucose Glycolysis
2 Pyruvate
2 NADH2 NAD+
+ 2 H+CO2
2 Acetaldehyde2 Ethanol
(a) Alcohol fermentation
2
Fig. 9.18
The solution when oxygen runs out or is unavailable (anaerobic conditions):
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Glycolysis and fermentation Fermentation to ethanol
2 ADP + 2Pi 2 ATP
Glucose Glycolysis
2 Pyruvate
2 NADH2 NAD+
+ 2 H+CO2
2 Acetaldehyde2 Ethanol(a) Alcohol fermentation
2
Fig. 9.18(a)
Yeasts use alcoholic fermentation to convert hexoses (from sugar cane sucrose or corn starch or
cellulose) into ethanol for fuels
Production of Foods & Fuels
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Alcohol fermentation (forms ethanol plus CO2)• Yeasts & bacteria• Anaerobic conditions
Glycolysis & fermentation
2 ADP + 2 P i 2 ATP
Glucose Glycolysis
2 Pyruvate
2 NADH2 NAD+
+ 2 H+CO2
2 Acetaldehyde2 Ethanol
(a) Alcohol fermentation
2
Fig. 9.18
Do all organisms use alcohol fermentation when oxygen is in
short supply?37
Alcohol fermentation (forms ethanol plus CO2)• Yeasts & bacteria• Anaerobic conditions
Glycolysis & fermentation without oxygen (anaerobic
conditions)
2 ADP + 2 P i 2 ATP
Glucose Glycolysis
2 Pyruvate
2 NADH2 NAD+
+ 2 H+CO2
2 Acetaldehyde2 Ethanol
(a) Alcohol fermentation
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Glucose
2 ADP + 2 Pi 2 ATP
Glycolysis
2 NAD+ 2 NADH
+ 2 H+
2 Pyruvate
2 Lactate
(b) Lactic acid fermentation
Fig. 9.18
Lactic acid fermentation • Other fungi & bacteria • Also in muscle cells under anaerobic conditions
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Production of Foods and Fuels by Microbes in home & industryYeasts for beer & wine [alcohol fermentation] & for bread leavening [from the CO2 gas formed]; lactic acid bacteria for fermented products from milk or other foods[lactic acid fermentation].
http://www.bact.wisc.edu/themicrobialworld/Effects.html39
Fermentation versus aerobic respiration
Different human muscle fibers use different metabolism (See also Table 49.1):
Glucose
Glycolysis
Pyruvate
CYTOSOL
Fermentation
Aerobic cellular respiration
MITOCHONDRION
Acetyl CoALactate
Citricacidcycle
Fig. 9.1940
Fermentation versus aerobic respiration
Different human muscle fibers use different metabolism (See also Table 49.1):
Glucose
Glycolysis
Pyruvate
CYTOSOL
Fermentation
Aerobic cellular respiration
MITOCHONDRION
Acetyl CoALactate
Citricacidcycle
Fig. 9.19
• Fast-twitch glycolytic fibers (for sprint) use glycolysis - quick, but does not provide much energy.
Glycogen
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Fermentation versus aerobic respiration
Different human muscle fibers use different metabolism (See also Table 49.1):
[Glucose]
Glycolysis
Pyruvate
CYTOSOL
Fermentation
Aerobic cellular respiration
MITOCHONDRION
Acetyl CoALactate
Citricacidcycle
Fig. 9.19
• Fast-twitch glycolytic fibers (for sprint) use glycolysis - quick, but does not provide much energy.
• Slow-twitch oxidative fibers (with many mitochondria for extended exercise) use oxidative respiration -slower, but yields much more energy.
Fats
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Glucose
Glycolysis
PyruvateCYTOSOL
No O2 present:Fermentation
O2 present:
Aerobic cellular respiration
MITOCHONDRION
Acetyl CoAEthanolor
lactateCitricacidcycle
Fig. 9.19
Fermentation in absence
of O2
Aerobic respiration in
presence of O2
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Hank’s Crash Course in Cellular Respiration
3:30-end
http://www.youtube.com/watch?v=00jbG_cfGuQ&feature=relmfu
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