Chapter 8Chapter 8

Cellular RespirationCellular Respiration

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Cellular EnergyCellular Energy

1)1) Uses of Energy Uses of Energy The ability to do workThe ability to do work

A) Most energy received by A) Most energy received by

burning of “fuels”.burning of “fuels”.

B) Energy released can be B) Energy released can be

converted to other forms.converted to other forms.

C) Carbon & Hydrogen combine C) Carbon & Hydrogen combine

with Oxygen to makewith Oxygen to make

Carbon dioxide and Water.Carbon dioxide and Water.

2) Energy from Food 2) Energy from Food (Carbohydrates)(Carbohydrates)

are the main sourceare the main source

A) Heat released is used to A) Heat released is used to

maintain body temperature.maintain body temperature.

B) Rest of energy is conserved in B) Rest of energy is conserved in

a chemical form.a chemical form.

C) Cell Respiration – the slow C) Cell Respiration – the slow release of food energy.release of food energy.

3) Food Energy is stored in 3) Food Energy is stored in molecules of ATPmolecules of ATP

A) Adenine – a base found in A) Adenine – a base found in

DNA & RNA.DNA & RNA.

B) Ribose – a 5-carbon sugar B) Ribose – a 5-carbon sugar

found in RNA.found in RNA.

C) Adenosine – combination of C) Adenosine – combination of

Adenine + Ribose.Adenine + Ribose.

D) Phosphate group – (PO4) D) Phosphate group – (PO4)

found in DNA & RNA.found in DNA & RNA.

E) Cells use similar molecules for E) Cells use similar molecules for different functions.different functions.

F) AMP – Adenosine Mono-F) AMP – Adenosine Mono-

Phosphate.Phosphate.

G) Energy is stored in High G) Energy is stored in High

Energy Phosphate Bonds.Energy Phosphate Bonds.

H) Energy is transferred when H) Energy is transferred when phosphates are removed.phosphates are removed.

I) Phosphorylation – transfer of a I) Phosphorylation – transfer of a phosphate.phosphate.

J) ATP ----> ADP + P + energyJ) ATP ----> ADP + P + energy

4) Sources of energy for ATP4) Sources of energy for ATP

A) Food energy used to add aA) Food energy used to add a Phosphate to ADP.Phosphate to ADP.

B) ATP then used for cellular B) ATP then used for cellular reactions.reactions.

C) Glucose supplies most cell C) Glucose supplies most cell energy (1Glucose = 36 ATP) energy (1Glucose = 36 ATP)

D) Energy is packaged in small, D) Energy is packaged in small, efficient units (ATP).efficient units (ATP).

5) Oxidation-Reduction reactions5) Oxidation-Reduction reactions

A) Oxidation – Electrons or A) Oxidation – Electrons or Hydrogen atoms removed.Hydrogen atoms removed.

B) Reduction – Electrons or B) Reduction – Electrons or Hydrogen atoms gained.Hydrogen atoms gained.

C) Redox reactions involve the C) Redox reactions involve the transfer of energy.transfer of energy.

D) Oxidation of glucose results in D) Oxidation of glucose results in energy release thru the loss energy release thru the loss

of electrons and hydrogen of electrons and hydrogen

atoms.atoms.

6) Hydrogen Acceptors – NAD & 6) Hydrogen Acceptors – NAD & FADFAD

A) Biological reactions involve A) Biological reactions involve Redox reactions.Redox reactions.

B) Enzymes require co-enzymes to B) Enzymes require co-enzymes to accept Hydrogen atoms and accept Hydrogen atoms and

their electrons.their electrons.

C) NAD – Nicotinamide Adenine C) NAD – Nicotinamide Adenine Dinucleotide. Dinucleotide.

D) FAD – Flavin Adenine D) FAD – Flavin Adenine Dinucleotide Dinucleotide (Riboflavin).(Riboflavin).

E) NAD + 2H E) NAD + 2H NADH2 NADH2 FAD + 2H FAD + 2H FADH2 FADH2

F) NADH2 & FADH2 are high F) NADH2 & FADH2 are high

energy energy molecules.molecules.

G) Energy from these are used to G) Energy from these are used to make ATP.make ATP.

7) Types of Respiration7) Types of RespirationAerobicAerobic – oxygen required. Glucose is – oxygen required. Glucose is completely broken down and completely broken down and maximum amount of energy is maximum amount of energy is released.released.

AnaerobicAnaerobic – no oxygen used. Glucose – no oxygen used. Glucose is partially broken down and a minimal is partially broken down and a minimal amount of energy is released.amount of energy is released.

Phases of respiration:Phases of respiration: Glycolysis, Glycolysis, Kreb’s Cycle, Electron Transport Kreb’s Cycle, Electron Transport SystemSystem

Copyright Pearson Prentice HallEnd Show

Slide 9 of 39

9-1 Chemical Pathways Overview of Cellular Respiration

Glycolysis takes place in the cytoplasm.

The Krebs cycle and electron transport take place in the mitochondria.

CytoplasmMitochondrion

Glycolysis

8) Glycolysis – splitting of glucose8) Glycolysis – splitting of glucose

ATP used as activation energyATP used as activation energy

Glucose splits into 2 PGAL Glucose splits into 2 PGAL moleculesmolecules

PGAL converted into Pyruvic Acid: PGAL converted into Pyruvic Acid:

2 NADH2 & 2 ATP produced2 NADH2 & 2 ATP produced

Net of 2 ATP produced in glycolysisNet of 2 ATP produced in glycolysis

9) Fermentation9) Fermentation

Fermentation is anaerobic Fermentation is anaerobic respiration.respiration.

Glycolysis is followed by the Glycolysis is followed by the conversion of pyruvic acid into conversion of pyruvic acid into lactic acid in animals & alcohol in lactic acid in animals & alcohol in plants.plants.

2 ATP’s and CO2 are produced.2 ATP’s and CO2 are produced.

Yeast fermentation used to bake Yeast fermentation used to bake bread.bread.

10) Kreb’s (Citric Acid) Cycle10) Kreb’s (Citric Acid) CycleCompletes the break down of glucose.Completes the break down of glucose.Pyruvic Acid enters MitochondriaPyruvic Acid enters MitochondriaPyruvic Acid converted into Acetic AcidPyruvic Acid converted into Acetic Acid2 NADH2 & 2 CO2 produced2 NADH2 & 2 CO2 producedEnzymes on Cristae complete rest of Enzymes on Cristae complete rest of reaction.reaction.All intermediates are recycled each All intermediates are recycled each turn.turn.Kreb’s cycle produces 4 CO2, 6 NADH2, Kreb’s cycle produces 4 CO2, 6 NADH2, 2 FADH2 & 2 ATP2 FADH2 & 2 ATP

11) Electron Transport System11) Electron Transport SystemElectron carriers accept hydrogens Electron carriers accept hydrogens from NADH2 & FADH2 and remove from NADH2 & FADH2 and remove energy.energy.Energy in hydrogens used to make Energy in hydrogens used to make ATP.ATP.Each NADH2 produces 3 ATP’sEach NADH2 produces 3 ATP’sEach FADH2 produces 2 ATP’sEach FADH2 produces 2 ATP’s32 ATP’s total produced by the ETS32 ATP’s total produced by the ETSOxygen is the final hydrogen acceptor Oxygen is the final hydrogen acceptor to form water in the last step.to form water in the last step.

Electron TransportElectron Transport

Electron TransportElectron Transport– The electron transport chain uses the The electron transport chain uses the

high-energy electrons from the Krebs high-energy electrons from the Krebs cycle to convert ADP into ATP.cycle to convert ADP into ATP.

Electron TransportElectron TransportHigh-energy electrons from NADH and FADHHigh-energy electrons from NADH and FADH22 are passed along the electron transport chain are passed along the electron transport chain from one carrier protein to the next.from one carrier protein to the next.

Electron TransportElectron Transport

At the end of the chain, an enzyme combines At the end of the chain, an enzyme combines these electrons with hydrogen ions and oxygen these electrons with hydrogen ions and oxygen to form water.to form water.

Electron TransportElectron TransportAs the final electron acceptor of the electron As the final electron acceptor of the electron

transport chain, oxygen gets rid of the low-energy transport chain, oxygen gets rid of the low-energy electrons and hydrogen ions.electrons and hydrogen ions.

Electron TransportElectron TransportWhen 2 high-energy electrons move down the When 2 high-energy electrons move down the

electron transport chain, their energy is used to electron transport chain, their energy is used to move hydrogen ions (Hmove hydrogen ions (H++) across the membrane.) across the membrane.

Electron TransportElectron Transport

During electron transport, HDuring electron transport, H+ + ions build up in the ions build up in the intermembrane space, so it is positively charged.intermembrane space, so it is positively charged.

Electron TransportElectron TransportThe other side of the membrane, from which those The other side of the membrane, from which those

HH+ + ions are taken, is now negatively charged.ions are taken, is now negatively charged.

Electron TransportElectron Transport

ATP synthase

The inner membranes of the mitochondria contain The inner membranes of the mitochondria contain protein spheres called ATP synthases.protein spheres called ATP synthases.

Electron TransportElectron TransportAs HAs H++ ions escape through channels into these ions escape through channels into these

proteins, the ATP synthase spins.proteins, the ATP synthase spins.

ATP synthase

Channel

Electron TransportElectron Transport

As it rotates, the enzyme grabs a low-energy ADP, As it rotates, the enzyme grabs a low-energy ADP, attaching a phosphate, forming high-energy ATP.attaching a phosphate, forming high-energy ATP.

ATP

ATP synthase

Channel

Electron TransportElectron TransportOn average, each pair of high-energy On average, each pair of high-energy electrons that moves down the electron electrons that moves down the electron transport chain provides enough energy to transport chain provides enough energy to produce three molecules of ATP from ADP.produce three molecules of ATP from ADP.