Download 9.2 The Process of Respiration

9.2 The Process of Respiration
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Lab Results After 24 Hours
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A. Glycolysis
Glucose Splitting
Takes place in the cytoplasm
Is Anaerobic. No Oxygen Required
Inputs: 1 Molecule of Glucose
2 Molecules of ATP
Outputs: 2 Molecules of Pyruvic Acid
4 Molecules of ATP
But since it cost us 2 ATP to start the process, the net gain is 2 ATP
Not much energy!
2 NADH (Electron carrier to Electron Transport Chain)
If O2 is present­ Pyruvic acid moves into Aerobic respiration with the Kreb's cycle/Citric acid cycle
If O2 is absent­ Fermentation Occurs
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Energy Investment
Energy Payoff
NET GAIN of 2 ATP
Electron energy stored in NADH will be used later to make ATP!
Advantages: 1. Makes Energy very fast
2. Does not need Oxygen
Disadvantages:
1. Not much energy is made
The Fate of Pyruvic Acid depends on the presence of Oxygen
If O2 is present Aerobic Respiration and the Kreb's cycle occurs If O2 absent­ Anaerobic Repiration occurs­ aka Fermentation
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B. Kreb's Cycle/Citric Acid Cycle (Follow the electrons)
Will only occur if O2 is present!!!
Input­ Pyruvic Acid from Glycolysis
Intermediate Molecule= Citric Acid (hence the name)
Output­ NAD+ NADH (Carry electrons and energy)
FAD+ FADH
6CO2 (From 2 Pyruvic Acids)
2 ATP (Not very much)
Every time a Carbon is removed­ 2 High Energy Electrons are Freed and stored by NAD and FAD
ATP= 1
Total Electron Pairs= 10***
Remember: Two Pyruvic Acids are formed from 1 Molecule of glucose, so for each Glucose Molecule, the Kreb's Cycle Spins Twice
Total Output is Doubled:
ATP= 2
NADH= 8 (16 electrons)
FADH= 2 (4 electrons)
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Citric Acid Cycle
aka
Kreb's Cycle
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C. Electron Transport Chain and ATP Synthesis
B
A
1. Electrons carried to the inner
membrane by NADH and FADH
are dropped off at the beginning (Cytochrome A)
2. As the electrons are passed along, their energy is used to pump H+ ions out of the matrix and into the intermembrane space
creating a Conc. Gradient (ACTIVE TRANSPORT)
3. The only way back into the matrix for H+ ions is through a protein called ATP Synthase. As H+ move through ATP Synthase like water through a dam, energy is used to convert ADP to ATP.
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Each pair of electrons can produce between two and three ATPs (Depends on if they came from NADH or FADH)
NADH= 28 ATP FADH= 4 ATP
Total of 32 ATPs created during ETC!!!!
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Energy Totals
Total of 36 ATP for each molecule of glucose 10
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Fermentation/Anaerobic Cellular Respiration
Occurs in the absence of Oxygen
If no O2 is present, No way to clear Electrons from ETC
NADH and FADH2 cannot drop off electrons meaning all NAD+ and FAD are occupied. This shuts down the
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Therefore there is nothing to do with the NADH from Glycolysis either.
but since glycolysis happens in the cytoplasm, it continues. In order to keep NAD+ available, those produced by this process drop off their electrons the first place they can (back to Pyruvate)
This converts the molecule pyruvate into new products (Form Dictates Function)
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In most animals, plants, and even bacteria the new molecule formed is Lactic Acid LACTIC ACID FERMENTATION
Pyruvic Acid
Lactic Acid
Lactobacillus
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In some single celled fungi called yeast, the new product is alcohol and CO2 ALCOHOLIC FERMENTATION
Ethanol aka ethyl alcohol
Pyruvic Acid
CO2
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