DMA:

1
DMA

• What is the reaction equation for aerobic
  cellular respiration?
• What is the difference between aerobic and
  anaerobic respiration?

2
Energy - Releasing Pathways

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 8

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Aerobic vs. Anaerobic

• All organisms can release energy stored in
  glucose and other compounds and use it in ATP
  production.
• To do aerobic respiration, oxygen must be
  present.
• Fermentation is an anaerobic process and can
  occur without oxygen present.
• Aerobic respiration yields more energy from
  glucose and occurs in the mitochondria. Not all
  organisms can do it!

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Aerobic Respiration

• Aerobic respiration reaction equation
• Influences
• Glucose concentration
• Oxygen present or absent?
• Aerobic respiration has three stages
• Glycolysis
• Krebs Cycle
• Electron Transport

C6H12O6 6O2 ? 6CO2 6H2O 36 ATP
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The Mitochondrion
inner compartment
outer compartment
cytoplasm
outer mitochondrial membrane
inner mitochondrial membrane
Fig. 8.5a, p. 136
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Aerobic Reaction Locations

• Glycolysis
• Cytoplasm
• Krebs Cycle
• Inner compartment
• Electron Transport System
• Cristae

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An Evolutionary Note
It is thought that there was an early reliance
on anaerobic respiration and later after the
endosymbiant events occurred, aerobic respiration
evolved.
2 ATP
36 ATP
Fig. 8.2, p. 132
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Glycolysis Splitting Glucose

• Glucose Reactant!
• 2 ATP needed to start process
• Substrate-level Phosphorylation
• 2NAD ?2NADH
• 4 ATP produced
• 2 NET ATP TOTAL!
• End-Product
• 2 molecules of pyruvate

GLUCOSE
in-text, p. 134
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Glycolysis The First Steps
Glucose
Uses ATP
P group
6 C
10
Glycolysis Second Stage
Uses ATP
P group
P group
3 C
3 C
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Glycolysis Third Stage
P group
Form NADH
Rebuild ATP
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Glycolysis Fourth Stage
2 pyruvate
Form ATP
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Glycolysis
http//koning.ecsu.ctstateu.edu/principles/images/
glycolysis.gif
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Glycolysis
http//library.thinkquest.org/C004535/media/glyco
lysis.gif
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Second Stage of the Aerobic Pathway Krebs Cycle

• Pyruvate enters mitochondria
• Krebs Cycle
• Inner compartment
• Electron Transport
• Inner membrane cristae

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Second Stage Reactions Preparatory Steps

• Pyruvate is stripped of a carboxyl group which
  departs as carbon dioxide (CO2)
• Pyruvate also gives up hydrogen and electrons to
  NAD to form NADH
• Coenzyme A joins with remaining two-carbon
  fragment to form acetyl-CoA

O CO CO H-C-H H
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The Linking Step!
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Krebs Cycle

• Acetyl-CoA transfers its two carbon fragment to
  oxaloacetate to start the cycle
• During the cycle -
• NAD and FAD are reduced to NADH and FADH2
• Substrate-level phosphorylation produces ATP
• Oxaloacetate is regenerated

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Krebs Cycle
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Electron Transport Phosphorylation

• Inner membrane cristae
• H concentration and electrical gradients
• ATP Synthases
• Formation of ATP from ADP and Pi by H flow
  chemiosmosis

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Electron Transport
http//www.stolaf.edu/people/giannini/flashanimat/
metabolism/mido20e20transport.swf
http//www.science.smith.edu/departments/Biology/B
io231/etc.html
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Self Study Topic
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Summary of the Energy Harvest

• Glycolysis
• 2 ATP by substrate-level phosphorylation
• 2 NADH (used to form 4 ATP during third stage)
• Krebs Cycle
• 2 ATP by substrate-level phosphorylation
• 2 FADH2 and 6 NADH
• Electron Transport Phosphorylation
• 32-34 ATP by electron transport phosphorylation

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Anaerobic Routes of ATP Formation

• Fermentation pathways
• Bacteria, yeasts and protistans

• Glycolysis - first step
• Net yield of two ATP
• Final product is lactate or ethanol

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Lactic Acid Fermentation

• Muscle cells in animals
• Quick ATP production
• Some bacteria

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Alcoholic Fermentation

• Acetaldehyde is intermediate product
• Yeasts

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Alternative Energy Sources in the Human Body

• Carbohydrates
• Production of ATP from metabolism
• Excess stored as glycogen in liver and muscle
  cells
• Fats
• Triglycerides
• Stored in adipose tissue
• Can be used for energy
• Proteins
• Growth, maintenance, repair
• Can be used for ATP production