Transcript Cell Respiration Notes (Honors)

Section 8.3
Cellular Respiration
Concept Map
Cellular Respiration
3 Stages
Glycolysis
Citric Acid Cycle
(Krebs Cycle)
Anaerobic
Electron
Transport Chain
Pyruvic Acid
Fermentation
Lactic Acid
Fermentation
Alcoholic
Fermentation
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Getting Energy to Make ATP
C6H12O6 + 6 O2  6CO2 + 6 H2O + ATP
The mitochondria in cells breaks down glucose
and produces energy-in this case ATP.
EXERGONIC: Releases energy
CATABOLIC: Breaking down
molecules
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Cellular Respiration
 Three stages of cellular respiration
1. Glycolysis - anaerobic
2. The Citric Acid Cycle (Kreb’s Cycle) - aerobic
3. The electron transport chain – aerobic
 The aerobic phase produces the most ATP
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Overview of Cellular Respiration
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Glycolysis
Takes place in the cytoplasm of the cell
It requires no oxygen (anaerobic).
Glucose (a 6 carbon molecule) is broken
down into 2 molecules of pyruvate (a 3
carbon compound).
It requires 2 ATP
It produces 4 ATP
A net gain of 2 ATP
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Glycolysis
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The Krebs Cycle
Takes place in the mitochondria of the cell (in
the matrix).
The pyruvate from glycolysis is slightly
modified before the citric acid cycle begins.
These new molecules are broken down to
form ATP and CO2.
One ATP per cycle is produced, two cycles
occur per glucose molecule – therefore 2
ATP’s are produced by Krebs Cycle.
*Also generates high energy electrons
carried by NADH and FADH2.
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Kreb’s Cycle/Citric Acid Cycle
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The Electron Transport Chain
(makes up to 34 ATP)
The final stage of respiration
Takes place on inner mitochrondrial membrane
(cristae)
Similar to the events in the light-dependent reactions
of photosynthesis.
Electrons are passed from protein to protein, and the
energy they give off is used to produce more ATP’s.
   The final electron acceptor is an oxygen
atom.
This is why we cannot live without oxygen!
Collects H+ ions and low energy electrons! (waste)
CREATES H2O (water)
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Electron Transport Chain
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Where do the electrons come from?
Electrons for the ETC come from electron
carriers: FADH2 and NADH
Work like NADPH (from photosynthesis)
Formation of FADH2 and NADH occurs during
glycolysis and citric acid cycle
Glycolysis
NAD+ and H+ combine with e- to make NADH
Citric Acid Cycle
More NADH forms
FAD+ and H+ combine with e- to make FADH2
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Respiration
One glucose molecule is capable of
producing a net amount of 36-38 ATP during
the entire process of cellular respiration.
2 in glycolysis
2 from the Krebs Cycle
32 to 34 from the electron transport chain
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Fermentation
When oxygen isn’t available, the aerobic
stages of respiration obviously can’t begin.
In this situation, fermentation begins after
glycolysis as an alternate form of respiration.
Why can glycolysis still go on?
Fermentation provides small amounts of ATP
until the cell can once again obtain enough
oxygen to begin the aerobic stages of
respiration. **does not last long**
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Fermentation
Two main types –
Alcoholic Fermentation
Common in yeast cells. CO2 and alcohol is
produced.
Example: bread
Lactic Acid Fermentation
Occurs in animal muscle cells. Lactic acid is
produced.
Example: pain in muscles from exercise
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Yeast in Bread
Yeast is a fungus
It consumes the
Sugar in the dough
-Dough is left to “rise”
-Yeast produces alcohol
and CO2 during
fermentation
-Alcohol evaporates as
bread cooks
-CO2 makes bubbles –
holes in bread
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ATP and Exercise
Running
Sprinting uses energy:
Stored in muscles: runs out quickly; within seconds
Made by lactic acid fermentation: (oxygen depleted)
made quickly, runs out quickly (about 90 seconds); lactic acid
produced = burning sensation in legs
Explains why a sprinter breathes very heavily at the end of a race
Long Term Energy
Made by cellular respiration: needs oxygen which is why
runners breathe heavily
Makes energy slower than fermentation; runners pace themselves
Glycogen stores last for about 15-20 minutes of activity
After that, body breaks down fats and other stored molecules for
energy
Aerobic Exercises = help with weight control
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