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Cellular Respiration
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Page 1: Cell respiration

Cellular Respiration

Page 2: Cell respiration
Page 3: Cell respiration

Figure 8.UN01Figure 8.UN01

Metabolic Pathways Often Require Multiple Steps

Enzyme 1 Enzyme 2 Enzyme 3

Reaction 1 Reaction 2 Reaction 3ProductStarting

molecule

A B C D

Page 4: Cell respiration

Figure 8.UN01Figure 8.UN01

Metabolic Pathways Often Require Multiple Steps

Enzyme 1 Enzyme 2 Enzyme 3

Reaction 1 Reaction 2 Reaction 3ProductStarting

molecule

A B C D

What happens when one of these steps goes awry?

Page 5: Cell respiration

Case Study: Why is Patrick Paralyzed?

Maureen Knabb

Department of Biology

West Chester University

Page 6: Cell respiration

Patrick at Ages 2 and 21Patrick at Ages 2 and 21

Patrick at 2: • When Patrick was 16 years old, his hand started twitching as he picked up a glass at dinner.

• Five months later (in February 2001), he fell down the steps at his home and was unable to climb the steps to the bus. He went to the ER for his progressive weakness.

• At Children’s Hospital of Philadelphia he was initially diagnosed with a demyelinating disease.

• He was treated with anti-inflammatory drugs and antibodies for 2 years with no improvement.

• What was wrong with Patrick?

By the time Patrick was 21 he was completely paralyzed

Why did Patrick lose his ability to move?

Page 7: Cell respiration

What could be responsible for Patrick’s What could be responsible for Patrick’s loss of mobility?loss of mobility?

A: His nervous system is not functioning properly.

B: His muscles are not functioning properly.

C: He cannot efficiently break down food for energy.

D: All of the above are possible causes.

Page 8: Cell respiration

Which of the following processes requires Which of the following processes requires energy?energy?

A: Creating ion gradients across membranes.

B: Muscle shortening.

C: Protein synthesis.

D: All of the above.

Page 9: Cell respiration

Figure 8.8aFigure 8.8a

(a) The structure of ATP

Adenosine Triphosphate (ATP) is the Primary Energy Carrier in the

Cell

Page 10: Cell respiration

3 Phosphate groups(triphosphate)

Adenine

Ribose(a) The structure of ATP

Figure 8.8a

Adenosine Triphosphate (ATP) is the Primary Energy Carrier in the

Cell

Page 11: Cell respiration

What would happen if Patrick lost his What would happen if Patrick lost his ability to make ATP?ability to make ATP?

A: His muscles would not be able to contract.

B: His neurons would not be able to conduct electrical signals.

C: Both A and B.

11

Page 12: Cell respiration

How is ATP generated?How is ATP generated?

• ATP is formed through metabolic pathways.

• In metabolic pathways, the product of one reaction is a reactant for the next.

• Each reaction is catalyzed by an enzyme.

12

Enzyme 1 Enzyme 2 Enzyme 3

Reaction 1 Reaction 2 Reaction 3ProductStarting

molecule

A B C D

Page 13: Cell respiration

What are enzymes?What are enzymes?• Enzymes (usually proteins)

are biological catalysts that are highly specific for their substrates (i.e., reactants).

• Enzymes are not consumed in the reaction.

• Enzymes lower the activation energy (the initial energy to start a reaction) of a reactiono Speed up chemical reactions

Page 14: Cell respiration

Course ofreactionwithoutenzyme

EA

withoutenzyme EA with

enzymeis lower

Course ofreactionwith enzyme

Reactants

Products

G is unaffectedby enzyme

Progress of the reaction

Free

ene

rgy

Page 15: Cell respiration

Enzyme RegulationEnzyme Regulation

• Enzymes turn “on” and “off” based on the needs of the cello Activators: Turn enzymes “ON”

• Positive allosteric regulation

o Inhibitors turn enzymes off• Irreversible = must make new

enzyme!• Reversible = inhibitor can “come

off”o Competitive inhibition =

active siteo Noncompetitive inhibition =

“other” site = allosteric site• Feedback Inhibition

Page 16: Cell respiration

CQ6: In competitive inhibition…CQ6: In competitive inhibition…

A: the inhibitor competes with the normal substrate for binding to the enzyme's active site.

B: an inhibitor permanently inactivates the enzyme by combining with one of its functional groups.

C: the inhibitor binds with the enzyme at a site other than the active site.

D: the competing molecule's shape does not resemble the shape of the substrate molecule.

Page 17: Cell respiration

Consider the metabolic pathway below. If the enzyme responsible for Consider the metabolic pathway below. If the enzyme responsible for converting A to C was mutated and nonfunctional, what would happen?converting A to C was mutated and nonfunctional, what would happen?

A: Levels of A would increase; levels of B, C, and D would decrease.

B: Levels of A and B would increase; levels of C and D would decrease.

C: Levels of A, B and C would increase; levels of D would decrease.

D: Levels of A, B, C, and D would all decrease.

A C DB

Page 18: Cell respiration

DNA mutations can disrupt DNA mutations can disrupt metabolic pathwaysmetabolic pathways

• Patrick suffered from a genetic disease that altered the structure of one protein.

• The protein was an enzyme.• The enzyme could potentially:

• lose its ability to catalyze a reaction.• lose its ability to be regulated.

• The enzyme that was mutated was involved in aerobic respiration

Page 19: Cell respiration

* The Stages of Aerobic RespirationThe Stages of Aerobic Respiration

Page 20: Cell respiration

* The Stages of Aerobic RespirationThe Stages of Aerobic Respiration

Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP

Page 21: Cell respiration

Overall yield = 2 ATP and 2 NADH + H+

Steps 1-3 Steps 4-6 Steps 7-10

ATP investment steps ATP producing steps

Occurs either with (aerobic) or without (anaerobic) oxygen.

Page 22: Cell respiration

• Glucose is not oxidized in a single step– It is broken down in a series of steps– Each step is catalyzed by an enzyme

• At key points, electrons are removed– Electrons travel with a proton (as a H atom)– H atoms are transferred to an electron carrier/acceptor, NAD+, via

a reduction-oxidation (redox) reaction• NAD+ is reduced* to NADH

VIP: Glycolysis Harvests Energy in a Stepwise Process

Page 23: Cell respiration

• Glucose is not oxidized in a single step– It is broken down in a series of steps– Each step is catalyzed by an enzyme

• At key points, electrons are removed– Electrons travel with a proton (as a H atom)– H atoms are transferred to an electron carrier/acceptor, NAD+, via

a reduction-oxidation (redox) reaction• NAD+ is reduced* to NADH

VIP: Glycolysis Harvests Energy in a Stepwise Process

*LEO goes GER: Losing Electrons is OxidationGaining Electrons is Reduction

Page 24: Cell respiration

NADNAD++ and NADH and NADH

Page 25: Cell respiration

* Figure 9.6-1Figure 9.6-1

Electronscarried

via NADH

Glycolysis

Glucose Pyruvate

CYTOSOL MITOCHONDRION

ATP

Substrate-levelphosphorylation

Glycolysis Produces Pyruvate and NADH…

Page 26: Cell respiration

* Figure 9.6-2Figure 9.6-2

Electronscarried

via NADH

Electrons carriedvia NADH (and

FADH2)

Citricacidcycle

Pyruvateoxidation

Acetyl CoA

Glycolysis

Glucose Pyruvate

CYTOSOL MITOCHONDRION

ATP ATP

Substrate-levelphosphorylation

Substrate-levelphosphorylation

The Pyruvate Feeds into the Citric Acid Cycle where…

Page 27: Cell respiration

* Figure 9.11Figure 9.11

Pyruvate

NAD

NADH+ H Acetyl CoA

CO2

CoA

CoA

CoA

2 CO2

ADP + P i

FADH2

FAD

ATP

3 NADH

3 NAD

Citricacidcycle

+ 3 H

…the Citric Acid Cycle Produces Even More NADH

Page 28: Cell respiration

* Figure 9.11Figure 9.11

Pyruvate

NAD

NADH+ H Acetyl CoA

CO2

CoA

CoA

CoA

2 CO2

ADP + P i

FADH2

FAD

ATP

3 NADH

3 NAD

Citricacidcycle

+ 3 H

…the Citric Acid Cycle Produces Even More NADH

Page 29: Cell respiration

Pyruvate

NAD

NADH+ H Acetyl CoA

CO2

CoA

CoA

CoA

2 CO2

ADP + P i

FADH2

FAD

ATP

3 NADH

3 NAD

Citricacidcycle

+ 3 H

…as well as some FADH2, some CO2 and more ATP

FADH2 is another electron carrier (similar to NADH)

Page 30: Cell respiration

Let’s review what we’ve done so far…

Glycolysis 1 Glucose (C6H12O6)

2 ATP + 2 NADH

2 Pyruvates (C3H3O3)

Energy Yield

Page 31: Cell respiration

Glycolysis

Citric Acid Cycle

1 Glucose (C6H12O6)2 ATP + 2 NADH

6 CO2 2 ATP + 8 NADH

+ 2 FADH2

2 Pyruvates (C3H3O3)

Energy Yield

Remember: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP

Let’s review what we’ve done so far…

Page 32: Cell respiration

* Figure 9.6-3Figure 9.6-3

Electronscarried

via NADH

Electrons carriedvia NADH and

FADH2

Citricacidcycle

Pyruvateoxidation

Acetyl CoA

Glycolysis

Glucose Pyruvate

Oxidativephosphorylation:electron transport

andchemiosmosis

CYTOSOL MITOCHONDRION

ATP ATP ATP

Substrate-levelphosphorylation

Substrate-levelphosphorylation

Oxidative phosphorylation

The NADH and FADH2 Feed into the Electron Transport Chain…

Page 33: Cell respiration

* Figure 9.15Figure 9.15

Proteincomplexof electroncarriers

(carrying electronsfrom food)

Electron transport chainOxidative phosphorylation

Chemiosmosis

I

II

IIIIVQ

Cyt c

FADFADH2

NADH ADP P iNAD

H

2 H + 1/2O2

H

HH

21

H

H2O

ATP

The Electron Transport ChainCoordinated Transport of High Energy Electrons is Coupled to

H+ Transport into the Inner Membrane Space

H

HH

H

H

H

ATPsynthase

Page 34: Cell respiration

* Figure 9.15Figure 9.15

Proteincomplexof electroncarriers

(carrying electronsfrom food)

Electron transport chainOxidative phosphorylation

Chemiosmosis

ATPsynthase

I

II

IIIIVQ

Cyt c

FADFADH2

NADH ADP P iNAD

H

2 H + 1/2O2

H

HH

21

H

H2O

ATP

ChemiosmosisEnergy from H+ movement down the concentration gradient is

used to make ATP via ATP synthase

H

HH

H

H

H

ATP

Page 35: Cell respiration

* Figure 9.15Figure 9.15

Proteincomplexof electroncarriers

(carrying electronsfrom food)

Electron transport chainOxidative phosphorylation

Chemiosmosis

I

II

IIIIVQ

Cyt c

FADFADH2

NADH ADP P iNAD

H

2 H + 1/2O2

H

HH

21

H

H2O

ATP

ChemiosmosisEnergy from H+ movement down the concentration gradient is

used to make ATP via ATP synthase

ATPsynthase

H

HH

Page 36: Cell respiration

Glycolysis 1 Glucose (C6H12O6)

2 ATP + 2 NADH

6 CO2 2 ATP + 8 NADH

+ 2 FADH2

2 Pyruvates (C3H3O3)

Energy Yield

Let’s Take a Final Talley…

Citric Acid Cycle

Page 37: Cell respiration

Glycolysis 1 Glucose (C6H12O6)

6 CO2

2 Pyruvates (C3H3O3)

Energy Yield

Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP

Let’s Take a Final Talley…

2 ATP + 2 NADH

2 ATP + 8 NADH + 2 FADH2

10 NADH + 2 FADH2

Citric Acid Cycle

Oxidative Phosphorylation

Page 38: Cell respiration

Glycolysis

Citric Acid Cycle

1 Glucose (C6H12O6)

6 CO2

2 Pyruvates (C3H3O3)

Energy Yield

Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP

Let’s Take a Final Talley…

Oxidative Phosphorylation

2 ATP + 2 NADH

2 ATP + 8 NADH + 2 FADH2

6 O2

10 NADH + 2 FADH2

6 O2

6 H2O

ETC

H+ gradient

Page 39: Cell respiration

Glycolysis

Citric Acid Cycle

1 Glucose (C6H12O6)

6 CO2

2 Pyruvates (C3H3O3)

Energy Yield

Overall Reaction: C6H12O6 + 6O2 6 CO2 + 6H2O + ATP

Let’s Take a Final Talley…

Oxidative Phosphorylation

2 ATP + 2 NADH

2 ATP + 8 NADH + 2 FADH2

6 O2

10 NADH + 2 FADH2

6 O2

6 H2O

ETC

H+ gradient

~32 ATPTotal: ~36 ATP

Page 40: Cell respiration

What Happens in the Absence of O2?

Page 41: Cell respiration

*Anaerobic RespirationAnaerobic RespirationGlycolysis Only•Make 2 ATP per glucose (rather than 32-36 ATP)

Page 42: Cell respiration

*Anaerobic RespirationAnaerobic RespirationGlycolysis Only•Make 2 ATP per glucose (rather than 32-36 ATP)•In yeast, ethanol is produced as a byproduct

Page 43: Cell respiration

*Anaerobic RespirationAnaerobic RespirationGlycolysis Only•Make 2 ATP per glucose (rather than 32-36 ATP)•In yeast, ethanol is produced as a byproduct•In animals, lactate is produced as a byproduct

Page 44: Cell respiration

*DNA mutations can disrupt DNA mutations can disrupt

metabolic pathways metabolic pathways

*Patrick suffered from a genetic disease that altered the structure of one protein.

*The protein was an enzyme.*The enzyme could potentially:

*lose its ability to catalyze a reaction.*lose its ability to be regulated.

*The enzyme that was mutated was involved in aerobic respiration

Page 45: Cell respiration

* Patrick suffered from lactate acidosisPatrick suffered from lactate acidosis

• Lactate (lactic acid) and pyruvate accumulated in his blood.• Acidosis led to:

o Hyperventilationo Muscle pain and weaknesso Abdominal pain and nausea

Page 46: Cell respiration

* What happened to Patrick?What happened to Patrick?• He inherited a mutation

leading to a disease called pyruvate dehydrogenase complex disease (PDCD).

• Pyruvate dehydrogenase is an enzyme that converts pyruvate to acetyl CoA inside the mitochondria.

• The brain depends on glucose as a fuel. PDCD degenerates gray matter in the brain.

• Pyruvate accumulates, leading to lactate accumulation in the blood (lactate acidosis).

Page 47: Cell respiration

* Why did Patrick become paralyzed?Why did Patrick become paralyzed?A: He inherited a genetic disease that resulted in the

partial loss of an enzyme necessary for aerobic breakdown of glucose.

B: The enzyme that is necessary for metabolizing fats was defective.

C: He was unable to synthesize muscle proteins due to defective ribosomes.

D: He suffered from a severe ion imbalance due to a high salt diet.