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Chapter 9: Cellular Respiration Cellular Respiration
Chapter 9: Cellular RespirationChapter 9: Cellular Respiration
Cellular Respiration
Cellular RespirationCellular RespirationCellular RespirationCellular RespirationLiving cells require energy from outside sources
Organisms use as their main energy
source
Cellular respiration is the process of breaking down food molecules to
Energy is released in the process of respiration when the cells of plants and animals convert sugar and oxygen into carbon dioxide and water
RespirationRespirationRespirationRespiration The breakdown of organic
molecules is respiration
consumes organic molecules and O2 and yields ATP (oxygen required)
respiration is similar to aerobic respiration but consumes compounds other than O2 (no oxygen required)
is a partial degradation of sugars that occurs without O2
The breakdown of organic molecules is
respiration consumes organic molecules and O2 and yields ATP (oxygen required)
respiration is similar to aerobic respiration but consumes compounds other than O2 (no oxygen required)
is a partial degradation of sugars that occurs without O2
Cellular RespirationCellular RespirationCellular RespirationCellular Respiration
Cellular respiration includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose:
Cellular respiration includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose:
Redox ReactionsRedox ReactionsRedox ReactionsRedox Reactions The transfer of electrons during chemical reactions
releases energy stored in organic molecules This released energy is used to make ATP Chemical reactions that transfer electrons between
reactants are called oxidation-reduction reactions, or
In oxidation, a substance , or is oxidized
In reduction, a substance , or is reduced (the amount of positive charge is reduced)
In cellular respiration, the glucose is and O2 is
The transfer of electrons during chemical reactions releases energy stored in organic molecules
This released energy is used to make ATP Chemical reactions that transfer electrons between
reactants are called oxidation-reduction reactions, or
In oxidation, a substance , or is oxidized
In reduction, a substance , or is reduced (the amount of positive charge is reduced)
In cellular respiration, the glucose is and O2 is
NAD+NAD+NAD+NAD+ In cellular respiration, glucose
and other organic molecules are broken down in a series of steps
Electrons from organic compounds are usually first transferred to NAD+
(nicotinamide adenine dinucleotide), a coenzyme As an electron acceptor, NAD+
functions as an Each NADH (the reduced form
of NAD+) represents stored energy that is tapped to synthesize ATP
NADH passes the electrons to the
In cellular respiration, glucose and other organic molecules are broken down in a series of steps
Electrons from organic compounds are usually first transferred to NAD+
(nicotinamide adenine dinucleotide), a coenzyme As an electron acceptor, NAD+
functions as an Each NADH (the reduced form
of NAD+) represents stored energy that is tapped to synthesize ATP
NADH passes the electrons to the
Electron Transport ChainElectron Transport ChainElectron Transport ChainElectron Transport Chain
Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction pulls
electrons down the chain in an energy-yielding tumble
The energy yielded is used to regenerate
Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction pulls
electrons down the chain in an energy-yielding tumble
The energy yielded is used to regenerate
Stages of Cellular Stages of Cellular RespirationRespiration
Stages of Cellular Stages of Cellular RespirationRespiration
1) - Anaerobic (breaks down glucose into two molecules of pyruvate)
2) - Aerobic (Kreb’s Cycle - completes the breakdown of glucose)
3) - Aerobic (ETC - accounts for most of the ATP synthesis)
1) - Anaerobic (breaks down glucose into two molecules of pyruvate)
2) - Aerobic (Kreb’s Cycle - completes the breakdown of glucose)
3) - Aerobic (ETC - accounts for most of the ATP synthesis)
MitochondriaMitochondriaMitochondriaMitochondria
1) Glycolysis
2) Citric Acid Cycle
3) Oxidative Phosphorylation (ETC)
1) Glycolysis
2) Citric Acid Cycle
3) Oxidative Phosphorylation (ETC)
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Step 1: GlycolysisStep 1: GlycolysisStep 1: GlycolysisStep 1: Glycolysis
Breaks down glucose
(C6H12O6) into two molecules of pyruvic acid - AKA
Anaerobic Occurs in the cytoplasm NAD picks up H+ and
electrons to form NADH2
Breaks down glucose
(C6H12O6) into two molecules of pyruvic acid - AKA
Anaerobic Occurs in the cytoplasm NAD picks up H+ and
electrons to form NADH2
Glycolysis SummaryGlycolysis SummaryGlycolysis SummaryGlycolysis Summary
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Simple Summary
Summary total
Bridge ReactionBridge ReactionBridge ReactionBridge Reaction In the presence of O2, pyruvate enters the mitochondrion Before the citric acid cycle can begin, pyruvate must be converted to
, which links the cycle to glycolysis In the mitochondria matrix…
1) Pyruvic Acid loses a C to form acetic acid (2-C)
2) The lost carbon binds with O2 making CO2
3)Acetic acid binds with Coenzyme-A forming Acetyl Co-A
In the presence of O2, pyruvate enters the mitochondrion Before the citric acid cycle can begin, pyruvate must be converted to
, which links the cycle to glycolysis In the mitochondria matrix…
1) Pyruvic Acid loses a C to form acetic acid (2-C)
2) The lost carbon binds with O2 making CO2
3)Acetic acid binds with Coenzyme-A forming Acetyl Co-A
Step 2: The Kreb’s CycleStep 2: The Kreb’s Cycle(Citric Acid Cycle)(Citric Acid Cycle)
Step 2: The Kreb’s CycleStep 2: The Kreb’s Cycle(Citric Acid Cycle)(Citric Acid Cycle)
Takes place within the mitochondrial matrix
There are , each catalyzed by a specific enzyme
The acetyl group of acetyl CoA joins the cycle by combining with (4-C molecule), forming a 6-C molecule known as
The next seven steps decompose the citrate back to oxaloacetate, making the process a cycle
Takes place within the mitochondrial matrix
There are , each catalyzed by a specific enzyme
The acetyl group of acetyl CoA joins the cycle by combining with (4-C molecule), forming a 6-C molecule known as
The next seven steps decompose the citrate back to oxaloacetate, making the process a cycle
Step 2: The Kreb’s CycleStep 2: The Kreb’s Cycle(Citric Acid Cycle)(Citric Acid Cycle)
Step 2: The Kreb’s CycleStep 2: The Kreb’s Cycle(Citric Acid Cycle)(Citric Acid Cycle)
2 molecules of CO2 are released (flavin adenine dinucleotide
- another ion carrier) pick up electrons and H+ becoming NADH and FADH2
The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain
The cycle generates 1 ATP, 3 NADH, and 1 FADH2 per turn
Recall that are formed during glycolysis resulting in of the Kreb’s cycle for each glucose molecule!
2 molecules of CO2 are released (flavin adenine dinucleotide
- another ion carrier) pick up electrons and H+ becoming NADH and FADH2
The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain
The cycle generates 1 ATP, 3 NADH, and 1 FADH2 per turn
Recall that are formed during glycolysis resulting in of the Kreb’s cycle for each glucose molecule!
Kreb’s Cycle SummaryKreb’s Cycle SummaryKreb’s Cycle SummaryKreb’s Cycle Summary
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Kreb’s Summary
Kreb's Summary 2
Step 3: Electron Transport Step 3: Electron Transport Chain (ETC)Chain (ETC)
Step 3: Electron Transport Step 3: Electron Transport Chain (ETC)Chain (ETC)
Aerobic process Requires as the
final electron acceptor Takes place in the cristae of
the mitochondria A series of molecules that
excited electrons pass along, to release energy as ATP
Most of the chain’s components are , which exist in multiprotein complexes
Aerobic process Requires as the
final electron acceptor Takes place in the cristae of
the mitochondria A series of molecules that
excited electrons pass along, to release energy as ATP
Most of the chain’s components are , which exist in multiprotein complexes
Step 3: Electron Transport Step 3: Electron Transport Chain (ETC)Chain (ETC)
Step 3: Electron Transport Step 3: Electron Transport Chain (ETC)Chain (ETC)
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
The carriers alternate as they accept and donate electrons
Electrons drop in free energy as they go down the chain
They are finally passed to O2 forming
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
The carriers alternate as they accept and donate electrons
Electrons drop in free energy as they go down the chain
They are finally passed to O2 forming
NADH and FADHNADH and FADH22NADH and FADHNADH and FADH22
Dump the electrons and protons they’ve gathered throughout glycolysis and the citric acid cycle
Again, O2 + 2e- + 2H+ H2O
Electrons are passed through a number of proteins including cytochromes (each with an iron atom) to O2
The chain’s function is to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
to generate large amounts of ATP
Dump the electrons and protons they’ve gathered throughout glycolysis and the citric acid cycle
Again, O2 + 2e- + 2H+ H2O
Electrons are passed through a number of proteins including cytochromes (each with an iron atom) to O2
The chain’s function is to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
to generate large amounts of ATP
ChemiosmosisChemiosmosisChemiosmosisChemiosmosis Electron transfer in the ETC causes
proteins to pump from the mitochondrial matrix to the intermembrane space
H+ then moves back across the membrane, passing through channels in (enzyme that acts like an ion pump)
ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ADP
This is an example of chemiosmosis, the use of energy in a H+ gradient to drive cellular work
The H+ gradient is called the
Electron transfer in the ETC causes proteins to pump from the mitochondrial matrix to the intermembrane space
H+ then moves back across the membrane, passing through channels in (enzyme that acts like an ion pump)
ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ADP
This is an example of chemiosmosis, the use of energy in a H+ gradient to drive cellular work
The H+ gradient is called the
ETC Summary
ETCETCETCETC
ETC SummaryETC SummaryETC SummaryETC Summary
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Simpler ETC Summary
Best ETC Summary
Whole Respiration ProcessWhole Respiration ProcessWhole Respiration ProcessWhole Respiration Process
Total EnergyTotal EnergyTotal EnergyTotal Energy
Total ATP from 1 molecule of glucose in Stage ATP + 4 TotalGlycolysis (b/c 2 are used in the first step) CA Cycle ETC
_________________ TOTAL During cellular respiration, most energy flows in this sequence: Glucose -> NADH -> electron transport chain -> proton-motive force -> ATP
FermentationFermentationFermentationFermentation
Most cellular respiration requires O2 to produce ATP
Glycolysis can produce ATP (in aerobic or anaerobic conditions)
In the absence of O2, glycolysis couples with fermentation or anaerobic respiration to produce ATP
Fermentation uses instead of an electron transport chain to generate ATP
2 Types: Fermentation Fermentation
Most cellular respiration requires O2 to produce ATP
Glycolysis can produce ATP (in aerobic or anaerobic conditions)
In the absence of O2, glycolysis couples with fermentation or anaerobic respiration to produce ATP
Fermentation uses instead of an electron transport chain to generate ATP
2 Types: Fermentation Fermentation
Lactic Acid FermentationLactic Acid FermentationLactic Acid FermentationLactic Acid Fermentation
In lactic acid fermentation, , forming lactate as an end product, with no release of CO2
Lactic acid fermentation by some fungi and bacteria is used to make
Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce
In lactic acid fermentation, , forming lactate as an end product, with no release of CO2
Lactic acid fermentation by some fungi and bacteria is used to make
Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce
Lactic Acid FermentationLactic Acid FermentationLactic Acid FermentationLactic Acid Fermentation
Example: Burning feeling in muscles during a workout
• From oxygen debt
•
• Lactate
Example: Burning feeling in muscles during a workout
• From oxygen debt
•
• Lactate
Alcohol FermentationAlcohol FermentationAlcohol FermentationAlcohol Fermentation In alcohol fermentation, pyruvate is
converted to (type of alcohol) in two steps, with the first releasing CO2
Bacteria and fungi (yeast) Alcohol fermentation by yeast is used
in
In alcohol fermentation, pyruvate is converted to (type of alcohol) in two steps, with the first releasing CO2
Bacteria and fungi (yeast) Alcohol fermentation by yeast is used
in
FermentationFermentationFermentationFermentation
Obligate anaerobes carry out fermentation or anaerobic respiration and
Yeast and many bacteria are facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration
Obligate anaerobes carry out fermentation or anaerobic respiration and
Yeast and many bacteria are facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration
Review
Role of MacromoleculesRole of MacromoleculesRole of MacromoleculesRole of Macromolecules
Catabolic pathways funnel electrons from many kinds of organic molecules into cellular respiration
Glycolysis accepts a wide range of Proteins must be digested to amino acids
Amino groups can feed Fats are digested to glycerol (used in glycolysis)
and fatty acids (used in generating acetyl CoA) Fatty acids are broken down by beta oxidation
and yield An oxidized gram of fat produces more than twice
as much ATP as an oxidized gram of carbohydrate
Catabolic pathways funnel electrons from many kinds of organic molecules into cellular respiration
Glycolysis accepts a wide range of Proteins must be digested to amino acids
Amino groups can feed Fats are digested to glycerol (used in glycolysis)
and fatty acids (used in generating acetyl CoA) Fatty acids are broken down by beta oxidation
and yield An oxidized gram of fat produces more than twice
as much ATP as an oxidized gram of carbohydrate
Regulation of Cell RespirationRegulation of Cell RespirationRegulation of Cell RespirationRegulation of Cell Respiration
Feedback inhibition is the most common mechanism for control If ATP concentration
begins to drop, respiration
When there is plenty of ATP, respiration
Control of catabolism is based mainly on regulating the activity of enzymes at strategic points in the catabolic pathway
Feedback inhibition is the most common mechanism for control If ATP concentration
begins to drop, respiration
When there is plenty of ATP, respiration
Control of catabolism is based mainly on regulating the activity of enzymes at strategic points in the catabolic pathway
Review QuestionsReview Questions1. Define cellular respiration and state its importance as a life process.2. Differentiate between aerobic respiration, anaerobic respiration, and
fermentation.3. State and explain the chemical equation for cellular respiration.4. Define oxidation and reduction and explain the idea of redox reactions.5. Explain the use of NAD+ as a coenzyme.6. Explain the electron transport chain (ETC).7. Name the 3 major stages of cell respiration, along with their locations.8. Explain glycolysis, stating the reactants, products, and major activities.9. Explain the bridge reaction, stating the reactants, products, and major
activities.10. Explain the Kreb’s cycle, stating the reactants, products, and major
activities.11. Explain glycolysis, stating the reactants, products, and major activities.12. Explain the ETC, stating the reactants, products, and major activities.13. Explain the role of oxygen in the ETC.14. Define chemiosmosis and explain its role in cellular respiration.15. Differentiate between lactic acid fermentation and alcohol
fermentation.16. Differentiate between oblicate anaerobes and facultative anaerobes.17. Explain the role of macromolecules in cellular respiration.18. Explain how cell respiration is regulated.
