Download Chapter 9 Cellular Respiration (working)

Chapter 9
Cellular Respiration:
Harvesting Chemical Energy
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-2
Light
energy
Energy flow
(one way)
and
chemical
recycling in
ecosystems
ECOSYSTEM
Photosynthesis
in chloroplasts
CO2 + H2O
Organic
+O
molecules 2
Cellular respiration
in mitochondria
ATP
ATP powers most cellular work
Heat
energy
Catabolic Pathways and Production of ATP
• The breakdown of organic molecules is exergonic –
energy is released
In exergonic reactions the energy stored in the
reactants is greater than the energy stored in the products
• Fermentation a catabolic process that makes a limited
amount of ATP from glucose without an electron transport
chain and that produces a characteristic end product, such
as ethyl alcohol or lactic acid
• Aerobic respiration consumes organic molecules and O2
and yields ATP
• Anaerobic respiration is similar to aerobic respiration but
consumes compounds other than O2
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-UN2
becomes oxidized
becomes reduced
becomes oxidized
becomes reduced
Fig. 9-UN3
Oxidation of Organic Fuel Molecules During
Cellular Respiration
becomes oxidized
becomes reduced
Fig. 9-4
2 e– + 2 H+
2 e– + H+
H+
NADH
Dehydrogenase
Reduction of NAD+
NAD+
+
+ H+
2[H]
Oxidation of NADH
Nicotinamide
(reduced form)
Nicotinamide
(oxidized form)
NAD serves as an electron
acceptor in cellular respiration to
become NADH (stored energy).
These electrons are “dropped off”
at the electron transport chain ETC
Fig. 9-5
H2 + 1/2 O2
2H
(from food via NADH)
Controlled
release of
+
–
2H + 2e
energy for
synthesis of
ATP
1/
2 O2
Explosive
release of
heat and light
energy
1/
(a) Uncontrolled reaction
2 O2
(b) Cellular respiration
Electrons keep moving “downhill” because
each carrier protein is more
electronegative
The Stages of Cellular Respiration: A Preview
•
Cellular respiration has three stages:
–
Glycolysis – occurs in the cytoplasm (breaks down glucose into
two molecules of pyruvate)
–
The citric acid cycle – occurs in the mitochondrial matrix
(completes the breakdown of glucose)
–
Oxidative phosphorylation – occurs on the inner mitochondrial
membrane (accounts for most of the ATP synthesis)
–
Glycolysis and the citric acid cycle are examples of substrate-level
phosphorylation – an enzyme transfers a phosphate from a
substance to ADP (Fig. 9.7)
–
Oxidative phosphorylation (occurs in ETC) is powered by redox
reactions
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-6-3
Electrons carried
via NADH and
FADH2
Electrons
carried
via NADH
Citric
acid
cycle
Glycolysis
Pyruvate
Glucose
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Mitochondrion
Cytosol
ATP
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation
Fig. 9-7
Glycolysis and the citric acid cycle are examples of substrate-level
phosphorylation – an enzyme transfers a phosphate from a substance to
ADP
Enzyme
Enzyme
ADP
P
Substrate
+
Product
http://highered.mheducation.com/sites/0072507470/student_view0/chapter25/an
imation__how_glycolysis_works.html
This link will guide you through all the steps of cellular respiration
ATP
Fig. 9-8
Energy investment phase
Glucose
2 ADP + 2 P
2 ATP
used
4 ATP
formed
Energy payoff phase
4 ADP + 4 P
2 NAD+ + 4 e– + 4 H+
2 NADH + 2 H+
2 Pyruvate + 2 H2O
Net
Glucose
4 ATP formed – 2 ATP used
2 NAD+ + 4 e– + 4 H+
2 Pyruvate + 2 H2O
2 ATP
2 NADH + 2 H+
Fig. 9-9-4
Coupling of reactions is the driving force that
keeps glycolysis moving
Glucose
ATP
1
Hexokinase
ADP
Glucose-6-phosphate
2
Phosphoglucoisomerase
Fructose1, 6-bisphosphate
4
Fructose-6-phosphate
ATP
Aldolase
3
Phosphofructokinase
ADP
5
Isomerase
Fructose1, 6-bisphosphate
4
Aldolase
5
Isomerase
Dihydroxyacetone
phosphate
Dihydroxyacetone
phosphate
Glyceraldehyde3-phosphate
Glyceraldehyde3-phosphate
Fig. 9-9-9
2 NAD+
6
Triose phosphate
dehydrogenase
2 Pi
2 NADH
+ 2 H+
2 1, 3-Bisphosphoglycerate
2 ADP
7 Phosphoglycerokinase
2 ATP
2
Phosphoenolpyruvate
2 ADP
2
3-Phosphoglycerate
8
Phosphoglyceromutase
2 ATP
2
10
Pyruvate
kinase
2-Phosphoglycerate
9
2 H2O
Enolase
2 Phosphoenolpyruvate
2 ADP
10
Pyruvate kinase
2 ATP
2
2
Pyruvate
Pyruvate
Concept 9.3: The citric acid cycle completes the
energy-yielding oxidation of organic molecules
• In the presence of O2, pyruvate enters the
mitochondrion
• Before the citric acid cycle can begin, pyruvate
must be converted to acetyl CoA, which links
the cycle to glycolysis
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-10
CYTOSOL
MITOCHONDRION
NAD+
NADH + H+
2
1
3
Acetyl CoA
Pyruvate
Transport protein
CO2
Coenzyme A
• The citric acid cycle, also called the Krebs
cycle, takes place within the mitochondrial
matrix
• The cycle oxidizes organic fuel derived from
pyruvate, generating 1 ATP, 3 NADH, and 1
FADH2 per turn
• Remember – Two turns take place for each 1
molecule of glucose, therefore a total of 2ATP,
6 NADH, and 2FADH2 are generated during
the Krebs cycle
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-11
Pyruvate
Remember – To
calculate the
inputs and
outputs on a perglucose basis,
multiply by 2,
because each
glucose molecule
is split during
glycolysis into
two pyruvate
moleucles
CO2
NAD+
CoA
NADH
+ H+
Acetyl CoA
CoA
CoA
Citric
acid
cycle
FADH2
2 CO2
3 NAD+
3 NADH
FAD
+ 3 H+
ADP + P i
ATP
Fig. 9-12-8
Acetyl CoA
CoA—SH
NADH
+H+
H2O
1
NAD+
8
Oxaloacetate
2
Malate
Citrate
Isocitrate
NAD+
Citric
acid
cycle
7
H2O
NADH
+ H+
3
CO2
Fumarate
CoA—SH
6
-Ketoglutarate
4
CoA—SH
5
FADH2
NAD+
FAD
Succinate
GTP GDP
ADP
ATP
Pi
Succinyl
CoA
NADH
+ H+
CO2
Concept 9.4: During oxidative phosphorylation,
chemiosmosis couples electron transport to ATP
synthesis
• Following glycolysis and the citric acid cycle,
NADH and FADH2 account for most of the
energy extracted from food
• These two electron carriers donate electrons to
the electron transport chain, which powers ATP
synthesis via oxidative phosphorylation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
The Pathway of Electron Transport
• The electron transport chain is in the cristae of the
mitochondrion (inner mitochondrial membrane)
• Most of the chain’s components are proteins,
which exist in multiprotein complexes
• The carriers alternate reduced and oxidized states
as they accept and donate electrons
• Electrons drop in free energy as they go down the
chain and are finally passed to O2, forming H2O
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-13
This process, in
which energy stored
in the form of a
hydrogen ion
gradient across a
membrane is used to
drive cellular work
such the synthesis of
ATP, is called
chemiosmosis. We
have previously used
the word osmosis in
discussing water
transport, but here it
refers to the flow of
H+ across a
membrane.
NADH
50
2 e–
NAD+
FADH2
2 e–
40

FMN
FAD
Multiprotein
complexes
FAD
Fe•S 
Fe•S
Q

Cyt b
30
Fe•S
Cyt c1
I
V
Cyt c
Cyt a
Cyt a3
20
10
2 e–
(from NADH
or FADH2)
0
2 H+ + 1/2 O2
H2O
Fig. 9-14
INTERMEMBRANE SPACE
H+
Stator
Rotor
Internal
rod
Catalytic
knob
ADP
+
P
i
ATP
MITOCHONDRIAL MATRIX
Fig. 9-16
H+
H+
H+
H+
Protein complex
of electron
carriers
Cyt c
V
Q


ATP
synthase

FADH2
NADH
2 H+ + 1/2O2
H2O
FAD
NAD+
ADP + P i
(carrying electrons
from food)
ATP
H+
1 Electron transport chain
Oxidative phosphorylation
2 Chemiosmosis
Fig. 9-17
Electron shuttles
span membrane
CYTOSOL
2 NADH
Glycolysis
Glucose
2
Pyruvate
MITOCHONDRION
2 NADH
or
2 FADH2
6 NADH
2 NADH
2
Acetyl
CoA
+ 2 ATP
Citric
acid
cycle
+ 2 ATP
Maximum per glucose:
About
36 or 38 ATP
2 FADH2
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ about 32 or 34 ATP
Concept 9.5: Fermentation and anaerobic
respiration enable cells to produce ATP without
the use of oxygen
• Most cellular respiration requires O2 to produce
ATP
• Glycolysis can produce ATP with or without O2 (in
aerobic or anaerobic conditions), therefore this
series of reactions evolved very early in
prokaryotic organisms before oxygen was present
in the atomosphere.
• In the absence of O2, glycolysis couples with
fermentation or anaerobic respiration to produce
ATP
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Types of Fermentation
•
Fermentation consists of glycolysis plus reactions that regenerate
NAD+, which can be reused by glycolysis. This is important because
there is only a limited supply of NAD+ in cells.
•
Two common types are alcohol fermentation and lactic acid
fermentation
•
In alcohol fermentation, pyruvate is converted to ethanol in two steps,
with the first releasing CO2
•
Alcohol fermentation by yeast is used in brewing, winemaking, and
baking
•
In lactic acid fermentation, pyruvate is reduced to NADH, forming
lactate as an end product, with no release of CO2
•
Lactic acid fermentation by some fungi and bacteria is used to make
cheese and yogurt
•
Human muscle cells use lactic acid fermentation to generate ATP
when O2 is scarce
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-18
2 ADP + 2 Pi
http://www.dnatube.co
m/video/5078/Fermenta
tion-Anaerobicrespiration-Lactic-Acidand-Ethanol
Glucose
2 ATP
Glycolysis
2 Pyruvate
2 NAD+
2 NADH
+ 2 H+
2 CO2
2 Acetaldehyde
2 Ethanol
(a) Alcohol fermentation
2 ADP + 2 Pi
Glucose
2 ATP
Glycolysis
2 NAD+
2 NADH
+ 2 H+
2 Pyruvate
2 Lactate
(b) Lactic acid fermentation
Fermentation and Aerobic Respiration Compared
• Both processes use glycolysis to oxidize
glucose and other organic fuels to pyruvate
• The processes have different final electron
acceptors: an organic molecule (such as
pyruvate or acetaldehyde) in fermentation and
O2 in cellular respiration
• Cellular respiration produces 36/38 ATP per
glucose molecule; fermentation produces 2
ATP per glucose molecule
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-19
Glucose
CYTOSOL
Glycolysis
Pyruvate
No O2 present:
Fermentation
O2 present:
Aerobic cellular
respiration
MITOCHONDRION
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle
The Evolutionary Significance of Glycolysis
• Glycolysis occurs in nearly all organisms
• Glycolysis probably evolved in ancient
prokaryotes before there was oxygen in the
atmosphere
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-20
Carbs., fats, and
proteins can all be
used as fuels for
cellular
respiration.
Monomers of
these molecules
enter glycolysis or
the citric acid
cycler at various
points. Glycolysis
and the citric acid
cycle are
catabolic funnels
through which
electrons from all
kinds of organic
molecules flow on
their exergonic fall
to oxygen.
Proteins
Carbohydrates
Amino
acids
Sugars
Glycolysis
Glucose
Glyceraldehyde-3- P
NH3
Pyruvate
Acetyl CoA
Citric
acid
cycle
Oxidative
phosphorylation
Fats
Glycerol
Fatty
acids
Fig. 9-21
Glucose
AMP
Enzymes at certain
points in the
respiratory pathway
respond to inhibitors
and activators that
help set the pace of
glycolysis and the
citric acid cycle.
This feedback
regulation adjusts
the rate of
respiration as the
cell’s catabolic and
anabolic demands
change.
Glycolysis
Fructose-6-phosphate
–
Stimulates
+
Phosphofructokinase
–
Fructose-1,6-bisphosphate
Inhibits
Inhibits
Pyruvate
ATP
Citrate
Acetyl CoA
Citric
acid
cycle
Oxidative
phosphorylation
Fig. 9-UN8
Pg. 184
#10
Time
Fig. 9-UN9