introduction in eukaryotes, cellular respiration –harvests energy from food, –yields large...
TRANSCRIPT
Introduction
In eukaryotes, cellular respiration
– harvests energy from food,
– yields large amounts of ATP, and
– Uses ATP to drive cellular work.
A similar process takes place in many prokaryotic organisms.
© 2012 Pearson Education, Inc.
Figure 6.0_1Chapter 6: Big Ideas
Cellular Respiration:Aerobic Harvesting
of Energy
Stages of CellularRespiration
Fermentation: AnaerobicHarvesting of Energy
Connections BetweenMetabolic Pathways
6.1 Photosynthesis and cellular respiration provide energy for life
Life requires energy.
In almost all ecosystems, energy ultimately comes from the sun.
In photosynthesis,
– some of the energy in sunlight is captured by chloroplasts,
– atoms of carbon dioxide and water are rearranged, and
– glucose and oxygen are produced.
© 2012 Pearson Education, Inc.
Figure 6.1
Sunlight energy
ECOSYSTEM
Photosynthesisin chloroplasts
Cellular respirationin mitochondria
(for cellularwork)
Heat energy
GlucoseCO2
H2O O2
ATP
Figure 6.2
Breathing
Lungs
BloodstreamCO2 O2
O2 CO2
Muscle cells carrying out
Cellular Respiration
Glucose O2 CO2 H2O ATP
Figure 6.3
Glucose Oxygen WaterCarbondioxide
C6H12O6 O2 H2O ATP6 6 6
Heat
CO2
6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen
Energy can be released from glucose by simply burning it.
The energy is dissipated as heat and light and is not available to living organisms.
© 2012 Pearson Education, Inc.
6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen
The movement of electrons from one molecule to another is an oxidation-reduction reaction, or redox reaction. In a redox reaction,
– the loss of electrons from one substance is called oxidation,
– the addition of electrons to another substance is called reduction,
– a molecule is oxidized when it loses one or more electrons, and
– reduced when it gains one or more electrons.
© 2012 Pearson Education, Inc.
Figure 6.5A
Glucose Heat
C6H12O6 O2 CO2 H2O ATP6 6 6
Loss of hydrogen atoms(becomes oxidized)
Gain of hydrogen atoms(becomes reduced)
Figure 6.5C
Controlledrelease ofenergy forsynthesisof ATP
NADH
NAD
H
H O2
H2O
2
2
2
ATP
Electron transport chain
21
6.6 Overview: Cellular respiration occurs in three main stages
Cellular respiration consists of a sequence of steps that can be divided into three stages.
– Stage 1 – Glycolysis
– Stage 2 – Pyruvate oxidation and citric acid cycle
– Stage 3 – Oxidative phosphorylation
© 2012 Pearson Education, Inc.
6.6 Overview: Cellular respiration occurs in three main stages
Stage 1: Glycolysis
– occurs in the cytoplasm,
– begins cellular respiration, and
– breaks down glucose into two molecules of a three-carbon compound called pyruvate.
© 2012 Pearson Education, Inc.
6.6 Overview: Cellular respiration occurs in three main stages
Stage 2: The citric acid cycle
– takes place in mitochondria,
– oxidizes pyruvate to a two-carbon compound, and
– supplies the third stage with electrons.
© 2012 Pearson Education, Inc.
6.6 Overview: Cellular respiration occurs in three main stages
Stage 3: Oxidative phosphorylation
– involves electrons carried by NADH and FADH2,
– shuttles these electrons to the electron transport chain embedded in the inner mitochondrial membrane,
– involves chemiosmosis, and
– generates ATP through oxidative phosphorylation associated with chemiosmosis.
© 2012 Pearson Education, Inc.
Figure 6.6_1
NADH
NADH FADH2
ATP ATPATP
CYTOPLASM
Glycolysis
Electronscarried by NADH
Glucose Pyruvate PyruvateOxidation
Citric AcidCycle
OxidativePhosphorylation
(electron transportand chemiosmosis)
Mitochondrion
Substrate-levelphosphorylation
Substrate-levelphosphorylation
Oxidativephosphorylation
Figure 6.7Ca_s1Glucose
Glucose 6-phosphate
Fructose 6-phosphate
Fructose 1,6-bisphosphate
ENERGYINVESTMENT
PHASE
P P
P
P
ADP
ADP
ATP
ATP
StepSteps – A fuelmolecule is energized,using ATP.
3
3
2
1
1
Figure 6.7Ca_s2Glucose
Glucose 6-phosphate
Fructose 6-phosphate
Fructose 1,6-bisphosphate
Glyceraldehyde3-phosphate (G3P)
ENERGYINVESTMENT
PHASE
PP
P P
P
P
ADP
ADP
ATP
ATP
StepSteps – A fuelmolecule is energized,using ATP.
Step A six-carbonintermediate splitsinto two three-carbonintermediates.
4
4
3
3
2
1
1
Figure 6.7Cb_s1
5 5 5Step A redox reactiongenerates NADH.
ENERGYPAYOFFPHASE
1,3-Bisphospho-glycerate
NADH NADH
NADNAD
H H
P P
P
P P
P
P P
Figure 6.7Cb_s2
66 6
5 5 5
9
9 9
8 8
7 7
Step A redox reactiongenerates NADH.
Steps – ATP and pyruvateare produced.
ENERGYPAYOFFPHASE
1,3-Bisphospho-glycerate
3-Phospho-glycerate
2-Phospho-glycerate
Phosphoenol-pyruvate (PEP)
Pyruvate
NADH NADH
NADNAD
H H
ADP ADP
ADP ADP
ATP ATP
ATP ATP
H2O H2O
P P
P
P P
P
P
P
P
P P
P
P
P
Figure 6.8
Pyruvate
Coenzyme A
Acetyl coenzyme A
NAD NADH H
CoA
CO2
3
2
1
Figure 6.9AAcetyl CoA
Citric Acid Cycle
CoA
CoA
CO22
3
3
NAD
3 H
NADH
ADPATP P
FAD
FADH2
Figure 6.9B_s3
NADH
NADH
NAD
NAD
NADNADH
H
H
H
CO2
CO2
ATP
ADP P
FAD
FADH2
CoA
CoA
321 4 5
34
5
1
2
Acetyl CoA
Oxaloacetate
Citric Acid Cycle
2 carbons enter cycle
Citrate
leaves cycle
Alpha-ketoglutarate
leaves cycle
Succinate
Malate
StepAcetyl CoA stokesthe furnace.
Steps –NADH, ATP, and CO2
are generated during redox reactions.
Steps –Further redox reactions generateFADH2 and more NADH.
Figure 6.10_1
H
H
H
H
H
H
H
H
H
H
H
Oxidative Phosphorylation
Electron Transport Chain Chemiosmosis
I
II
IIIIV
NADH NAD 2 H
FADH2FAD
O2 H2O
ADP P ATP
21
Electronflow
Proteincomplexof electroncarriers
Mobileelectroncarriers
ATPsynthase
6.12 Review: Each molecule of glucose yields many molecules of ATP
Recall that the energy payoff of cellular respiration involves
1. glycolysis,
2. alteration of pyruvate,
3. the citric acid cycle, and
4. oxidative phosphorylation.
© 2012 Pearson Education, Inc.
Figure 6.12
NADH
FADH2
NADH FADH2NADH
orNADH
MitochondrionCYTOPLASM
Electron shuttlesacross membrane
Glycolysis
Glucose2
Pyruvate
PyruvateOxidation2 Acetyl
CoA
Citric AcidCycle
OxidativePhosphorylation
(electron transportand chemiosmosis)
Maximumper glucose:
by substrate-levelphosphorylation
by substrate-levelphosphorylation
by oxidativephosphorylation
2
2
2
2
6 2
ATP 2 about
28 ATP AboutATP32
ATP 2
© 2012 Pearson Education, Inc.
Animation: Fermentation OverviewRight click on animation / Click play
Figure 6.13A
2 NAD
2 NADH
2 NAD
2 NADH
2 Lactate
2 Pyruvate
Glucose
2 ADP
2 ATP
2 P
Gly
coly
sis
Figure 6.13B
2 NAD
2 NADH
2 NAD
2 NADH
2 Ethanol
2 Pyruvate
Glucose
2 ADP
2 ATP
2 P
Gly
coly
sis
2 CO2
6.14 EVOLUTION CONNECTION: Glycolysis evolved early in the history of life on Earth
The ancient history of glycolysis is supported by its
– occurrence in all the domains of life and
– location within the cell, using pathways that do not involve any membrane-bounded organelles.
© 2012 Pearson Education, Inc.
CONNECTIONS BETWEEN METABOLIC PATHWAYS
© 2012 Pearson Education, Inc.
6.15 Cells use many kinds of organic molecules as fuel for cellular respiration
Although glucose is considered to be the primary source of sugar for respiration and fermentation, ATP is generated using
– carbohydrates,
– fats, and
– proteins.
© 2012 Pearson Education, Inc.
Figure 6.15
Food, such aspeanuts
Sugars Glycerol Fatty acids Amino acids
Aminogroups
OxidativePhosphorylation
CitricAcidCycle
PyruvateOxidation
Acetyl CoA
ATP
Glucose G3P PyruvateGlycolysis
Carbohydrates Fats Proteins
Figure 6.16
CarbohydratesFatsProteins
Cells, tissues, organisms
Amino acids Fatty acids Glycerol Sugars
Aminogroups
CitricAcidCycle
PyruvateOxidation
Acetyl CoA
ATP neededto drivebiosynthesis
ATP
Glucose SynthesisPyruvate G3P Glucose
You should now be able to
1. Compare the processes and locations of cellular respiration and photosynthesis.
2. Explain how breathing and cellular respiration are related.
3. Provide the overall chemical equation for cellular respiration.
4. Explain how the human body uses its daily supply of ATP.
© 2012 Pearson Education, Inc.
You should now be able to
5. Explain how the energy in a glucose molecule is released during cellular respiration.
6. Explain how redox reactions are used in cellular respiration.
7. Describe the general roles of dehydrogenase, NADH, and the electron transport chain in cellular respiration.
8. Compare the reactants, products, and energy yield of the three stages of cellular respiration.
© 2012 Pearson Education, Inc.
You should now be able to
9. Explain how rotenone, cyanide, carbon monoxide, oligomycin, and uncouplers interrupt critical events in cellular respiration.
10. Compare the reactants, products, and energy yield of alcohol and lactic acid fermentation.
11. Distinguish between strict anaerobes and facultative anaerobes.
12. Explain how carbohydrates, fats, and proteins are used as fuel for cellular respiration.
© 2012 Pearson Education, Inc.
Figure 6.UN01
Substrate-levelphosphorylation
Substrate-levelphosphorylation
OxidativephosphorylationATP ATP
ATP
NADH
NADH FADH2
Mitochondrion
GlycolysisPyruvateOxidation
CitricAcidCycle
OxidativePhosphorylation
(electron transportand chemiosmosis)
Electronscarried by NADH
Glucose Pyruvate
CYTOPLASM
Figure 6.UN02
cellular work
chemiosmosis
H gradient
glucose andorganic fuels
Cellularrespiration
generates has three stages oxidizes
uses
producesome
producesmany
to pullelectrons down
H diffusethrough
ATP synthase
pumps H to createuses
usesby a process called
energy for
(a)
(b)
(c)
(d)
(e)
(f)
(g)
to