Jommm

Only available on StudyMode
  • Download(s) : 11
  • Published : February 6, 2013
Open Document
Text Preview
Chapter 9

Cellular Respiration:
Harvesting Chemical Energy
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece

Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Overview: Life Is Work
• Living cells
– Require transfusions of energy from outside
sources to perform their many tasks

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• The giant panda
– Obtains energy for its cells by eating plants

Figure 9.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Energy
– Flows into an ecosystem as sunlight and
leaves as heat
Light energy
ECOSYSTEM

Photosynthesis
in chloroplasts
Organic
CO2 + H2O
+ O2
Cellular
molecules
respiration
in mitochondria

ATP
powers most cellular work

Figure 9.2
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Heat
energy

• Concept 9.1: Catabolic pathways yield energy
by oxidizing organic fuels

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Catabolic Pathways and Production of ATP
• The breakdown of organic molecules is
exergonic

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• One catabolic process, fermentation
– Is a partial degradation of sugars that occurs
without oxygen

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

FERMENTATION IN PLANT AND ANIMAL CELLS
ANIMAL
CELLS

PLANT
CELLS

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Cellular respiration
– Is the most prevalent and efficient catabolic
pathway
– Consumes oxygen and organic molecules
such as glucose

– Yields ATP

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• To keep working
– Cells must regenerate ATP

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Redox Reactions: Oxidation and Reduction
• Catabolic pathways yield energy
– Due to the transfer of electrons

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

The Principle of Redox
• Redox reactions
– Transfer electrons from one reactant to
another by oxidation and reduction

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• In oxidation
– A substance loses electrons, or is oxidized

• In reduction
– A substance gains electrons, or is reduced

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Examples of redox reactions

becomes oxidized
(loses electron)

Na

+

Cl

Na+

+

becomes reduced
(gains electron)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Cl–

• Some redox reactions
– Do not completely exchange electrons

– Change the degree of electron sharing in
covalent bonds
Products

Reactants
becomes oxidized

+

CH4

CO

2O2

+

Energy

2 H2O

becomes reduced

O

O

C

O

H

O

O

H

H
H

C

+

2

H

H
Methane
(reducing
agent)

Oxygen
(oxidizing
agent)

Figure 9.3
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Carbon dioxide

W ater

Oxidation of Organic Fuel Molecules During
Cellular Respiration
• During cellular respiration
– Glucose is oxidized and oxygen is reduced
becomes oxidized

C6H12O6 + 6O2

6CO2 + 6H2O + Energy
becomes reduced

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Stepwise Energy Harvest via NAD+ and the Electron
Transport Chain

• Cellular respiration
– Oxidizes glucose in a series of steps

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Electrons from organic compounds
– Are usually first transferred to NAD+, a
coenzyme
2 e– + 2 H+

NAD+
Dehydrogenase

O
NH2

H

C

CH2

O
O–

O

OP
O
H
– HO
OPO
O...
tracking img