Download Electron Transport

Cellular Respiration
Slide
1 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
9-1 Chemical Pathways
Food serves as a source of raw materials for the
cells in the body and as a source of energy.
Animal Cells
Animal
Mitochondrion
Plant
Plant Cells
Copyright Pearson Prentice Hall
Slide
2 of 39
End Show
9-1 Chemical Pathways
Both plant and animal cells carry out the final
stages of cellular respiration in the mitochondria.
Animal Cells
Outer membrane
Intermembrane
Mitochondrion
space
Inner
membrane
Matrix
Plant Cells
Copyright Pearson Prentice Hall
Slide
3 of 39
End Show
Chemical Energy and Food
Chemical Energy and Food
One gram of the sugar glucose
(C6H12O6), when burned in the presence
of oxygen, releases 3811 calories of heat
energy.
A calorie is the amount of energy
needed to raise the temperature of 1 gram
of water 1 degree Celsius.
Slide
4 of 39
Copyright Pearson Prentice Hall
End Show
Overview of Cellular Respiration
What is cellular respiration?
Slide
5 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
Overview of Cellular Respiration
Electrons carried in NADH
Electrons carried
in NADH and
FADH2
Pyruvic
acid
Glucose
Glycolysis
Cytoplasm
Mitochondrion
Slide
6 of 39
Copyright Pearson Prentice Hall
End Show
Overview of Cellular Respiration
Cellular respiration is the process that
releases energy by breaking down
glucose and other food molecules in the
presence of oxygen.
3 parts:
Glycolysis
Krebs Cycle
Electron Transport Chain
Copyright Pearson Prentice Hall
Slide
7 of 39
End Show
Overview of Cellular Respiration
The equation for cellular respiration is:
6O2 + C6H12O6 → 6CO2 + 6H2O +
Energy
oxygen + glucose → carbon dioxide + water +
Energy
Slide
8 of 39
Copyright Pearson Prentice Hall
End Show
Overview of Cellular Respiration
Glycolysis takes place in the
cytoplasm. The Krebs cycle and electron
transport take place in the mitochondria.
Glycolysis
Cytoplasm
Mitochondrion
Slide
9 of 39
Copyright Pearson Prentice Hall
End Show
Glycolysis
What happens during the
process of glycolysis?
Slide
10 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
Glycolysis
ATP Production
At the beginning of glycolysis, the cell uses up 2
molecules of ATP to start the reaction.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2 Pyruvic
acid
Slide
11 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
Glycolysis
When glycolysis is complete, 4 ATP molecules
have been produced.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2 Pyruvic
acid
Slide
12 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
Glycolysis
This gives the cell a net gain of 2 ATP molecules.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2 Pyruvic
acid
Slide
13 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
Glycolysis
NADH Production
One reaction of glycolysis removes 4 high-energy
electrons, passing them to an electron carrier
called NAD+.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2NAD+
2 Pyruvic
acid
Slide
14 of 39
Copyright Pearson Prentice Hall
End Show
9-1 Chemical Pathways
Glycolysis
Each NAD+ accepts a pair of high-energy electrons
and becomes an NADH molecule.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2NAD+
2
2 Pyruvic
acid
Slide
15 of 39
Copyright Pearson Prentice Hall
End Show
Glycolysis
The NADH molecule holds the
electrons until they can be transferred to
other molecules.
2 ATP
2 ADP
4 ADP
2NAD+
4 ATP
2
2 Pyruvic
acid
To the electron
transport chain
Copyright Pearson Prentice Hall
Slide
16 of 39
End Show
Glycolysis
The Advantages of
Glycolysis
The process of glycolysis is so fast that
cells can produce thousands of ATP
molecules in a few milliseconds.
Glycolysis does not require oxygen.
Slide
17 of 39
Copyright Pearson Prentice Hall
End Show
9-2 The Krebs Cycle and
Electron Transport
Oxygen is required for the final steps of
cellular respiration.
Because the pathways of cellular
respiration require oxygen, they are
aerobic.
Slide
18 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
What happens during the
Krebs cycle?
Slide
19 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
During the Krebs cycle, pyruvic
acid is broken down into carbon
dioxide in a series of energyextracting reactions.
Slide
20 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
The Krebs cycle
begins when pyruvic
acid produced by
glycolysis enters the
mitochondrion.
Slide
21 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
One carbon
molecule is
removed, forming
CO2, and electrons
are removed,
changing NAD+ to
NADH.
Slide
22 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
Coenzyme A joins
the 2-carbon
molecule, forming
acetyl-CoA.
Slide
23 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
Acetyl-CoA then
adds the 2-carbon
acetyl group to a 4carbon compound,
forming citric acid.
Citric acid
Slide
24 of 39
Copyright Pearson Prentice Hall
End Show
Citric acid is broken down into a 5-carbon
compound, then into a 4-carbon
compound.
The Krebs Cycle
Slide
25 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
Two more molecules of CO2 are released and
electrons join NAD+ and FAD, forming NADH and
FADH2
Slide
26 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
In addition, one molecule of ATP is generated.
Slide
27 of 39
Copyright Pearson Prentice Hall
End Show
The Krebs Cycle
The energy tally from 1 molecule of pyruvic acid
is
•
•
•
4 NADH
1 FADH2
1 ATP
Slide
28 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
How are high-energy
electrons used by the
electron transport chain?
Slide
29 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
Electron Transport
The electron transport
chain uses the high-energy
electrons from the Krebs
cycle to convert ADP into
ATP.
Slide
30 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
High-energy electrons from NADH and FADH2 are
passed along the electron transport chain from one
carrier protein to the next.
Slide
31 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
At the end of the chain, an enzyme combines
these electrons with hydrogen ions and oxygen to
form water.
Slide
32 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
As the final electron acceptor of the electron
transport chain, oxygen gets rid of the low-energy
electrons and hydrogen ions.
Slide
33 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
When 2 high-energy electrons move down the
electron transport chain, their energy is used to
move hydrogen ions (H+) across the membrane.
Slide
34 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
During electron transport, H+ ions build up in the
intermembrane space, so it is positively charged.
Slide
35 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
The other side of the membrane, from which those
H+ ions are taken, is now negatively charged.
Slide
36 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
The inner membranes of the mitochondria contain
protein spheres called ATP synthases.
ATP
synthase
Slide
37 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
As H+ ions escape through channels into these
proteins, the ATP synthase spins.
Channel
ATP
synthase
Slide
38 of 39
Copyright Pearson Prentice Hall
End Show
Electron Transport
As it rotates, the enzyme grabs a low-energy ADP,
attaching a phosphate, forming high-energy ATP.
Channel
ATP
synthase
ATP
Slide
39 of 39
Copyright Pearson Prentice Hall
End Show
The Totals
The Totals
Glycolysis produces just 2 ATP
molecules per molecule of glucose.
The complete breakdown of glucose
through cellular respiration, including
glycolysis, results in the production of 36
molecules of ATP.
Slide
40 of 39
Copyright Pearson Prentice Hall
End Show
The Totals
Slide
41 of 39
Copyright Pearson Prentice Hall
End Show
Comparing Photosynthesis
and Cellular Respiration
Comparing Photosynthesis and Cellular Respiration
The energy flows in photosynthesis
and cellular respiration take place in
opposite directions.
Slide
42 of 39
Copyright Pearson Prentice Hall
End Show
Comparing Photosynthesis and Cellular Respiration
On a global level, photosynthesis and
cellular respiration are also opposites.
•
Photosynthesis removes carbon
dioxide from the atmosphere and cellular
respiration puts it back.
•
Photosynthesis releases oxygen into
the atmosphere and cellular respiration
uses that oxygen to release energy from
food.
Slide
43 of 39
Copyright Pearson Prentice Hall
End Show
• What happens when there
is no oxygen present???
Slide
44 of 39
Copyright Pearson Prentice Hall
End Show
Fermentation
Fermentation
When oxygen is not present, glycolysis
is followed by a different pathway.
The combined process of this pathway
and glycolysis is called fermentation.
Fermentation releases energy from
food molecules by producing ATP in the
absence of oxygen.
Slide
45 of 39
Copyright Pearson Prentice Hall
End Show
Common Foods that use
fermentation
• Coffee
• Salami
• Chocolate
• Beer
• Tea
• Wine
• Sourdough bread
• Sauerkraut
• Cheese
• Pickles
• Yogurt
• vinegar
Slide
46 of 39
Copyright Pearson Prentice Hall
End Show
Fermentation
What are the two main
types of fermentation?
Slide
47 of 39
Copyright Pearson Prentice Hall
End Show
Alcoholic Fermentation
Yeasts and a few other
microorganisms use alcoholic
fermentation, forming ethyl alcohol and
carbon dioxide as wastes.
The equation for alcoholic fermentation
after glycolysis is:
pyruvic acid + NADH → alcohol + CO2
+ NAD+
Slide
48 of 39
Copyright Pearson Prentice Hall
End Show
Slide
49 of 39
Copyright Pearson Prentice Hall
End Show
Slide
50 of 39
Copyright Pearson Prentice Hall
End Show
Fermentation
Lactic Acid Fermentation
In many cells, pyruvic acid that accumulates as
a result of glycolysis can be converted to lactic
acid.
This type of fermentation is called lactic acid
fermentation. It regenerates NAD+ so that
glycolysis can continue.
The equation for lactic acid fermentation after
glycolysis is:
Slide
51 of 39
pyruvic acid + NADH → lactic acid + NAD+End Show
Copyright Pearson Prentice Hall
• Lactic acid build up in the muscles
causes a burning sensation –
caused by the lack of Oxygen
Slide
52 of 39
Copyright Pearson Prentice Hall
End Show
Slide
53 of 39
Copyright Pearson Prentice Hall
End Show