Download Glycolysis, Krebs Cycle, and other Energy

Aerobic Respiration
All organisms produce ATP by releasing energy stored in glucose and other sugars.
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Plants make ATP during photosynthesis.
All other organisms, including plants, must produce ATP by breaking down
molecules such as glucose…So yes PLANTS CARRY OUT RESPIRATION
Aerobic respiration - the process by which a cell uses O2 to "burn" molecules and
release energy
The reaction: C6H12O6 + 6O2  6CO2 + 6H2O and 36 ATP
Note: this reaction is the opposite of photosynthesis
This reaction takes place over the course of three major reaction pathways
1. Glycolysis (2 stages)
o The breaking down oof glucose to pyruvate
2. The Krebs Cycle
o Breaks down Pyruvate into CO2 and water, ATP
o NAD and FAD accept H+ ions and electrons to be carried to the ETC
3. Electron Transport Chain Phosphorylation (chemiosmosis)
o Processes the H+ ions and electrons to generate High yields of ATP
o Oxygen is final electron Acceptor
1. Glycolysis (glyco = sugar; lysis = breaking)
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Goal: break glucose down to form two pyruvates
Who: all life on earth performs glyclolysis
Where: enzymes in the Cytoplasm break down Glucose
Enzymes remove H+ fomr PGAL and Form NADH (used later in ETC)
Glycolysis produces 4 ATP's and 2 NADH, but uses 2 ATP's in the process for a net
of 2 ATP and 2 NADH
NOTE: this process does not require O2 and does not yield much energy
A. The First Stage of Glycolysis
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Glucose (6C) is broken down into 2 PGAL's (Phosphoglyceraldehyde - 3Carbon
molecules)
This requires two ATP's
B. The Second Stage of Glycolysis
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2 PGAL's (3C) are converted to 2 pyruvates
This creates 4 ATP's and 2 NADH's
The net ATP production of Glycolysis is 2 ATP's
2. The Oxidation of Pyruvate and Krebs Cycle
AKA (citric acid cycle)
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Goal: take pyruvate and put it into the Krebs cycle, producing NADH and FADH2
Where: the mitochondria
There are two steps
o The Conversion of Pyruvate to Acetyl CoA
o The Krebs Cycle
The Krebs cycle and the conversion of pyruvate to Acetyl CoA produce:
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2 ATP's,
o 8 NADH's,
o CO2
o 2FADH2's per glucose molecule
A. The Oxidation of Pyruvate (to form Acetyl CoA for use In Krebs Cycle)
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2 NADH's are generated (1 per pyruvate)
2 CO2 are released (1 per pyruvate)
B. The Krebs Cycle
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6 NADH's are generated (3 per Acetyl CoA that enters)
2 FADH2 is generated (1 per Acetyl CoA that enters)
2 ATP are generated (1 per Acetyl CoA that enters)
4 CO2's are released (2 per Acetyl CoA that enters)
Therefore, the total numbers of molecules generated in the oxidation of pyruvate
and the Krebs Cycle is:
o 8 NADH
o 2 FADH2
o 2 ATP
o 6 CO2
3. Electron Transport Chain Phosphorylation (Chemiosmosis)
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Goal:
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to break down NADH and FADH2 give up their electrons to transfer
enzyme systems embedded in the membrane,
o pumping H+ into the outer compartment of the mitochondria
Where: the mitochondria membranes
In this reaction, the ETC creates a H+ ion gradient which is used to produce ATP,
(quite like in the chloroplast)
ATP is generated as H+ moves down its concentration gradient through a special
enzyme called ATP synthase (Complex IV in the diagram)
ATP Synthase channels bond a P+ to ADP forming ATP
Oxygen joins with the “used” electrons and H+ to yield water
Electron Transport Phosphorylation typically produces 32 ATP's
Net Energy Production from Aerobic Respiration
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Glycolysis: 2 ATP
Krebs Cycle: 2 ATP
Electron Transport Phosphorylation: 32 ATP
o Each NADH produced in Glycolysis is worth 2 ATP (2 x 2 = 4) - the
NADH is worth 3 ATP, but it costs an ATP to transport the NADH into
the mitochondria, so there is a net gain of 2 ATP for each NADH
produced in gylcolysis
o Each NADH produced in the conversion of pyruvate to acetyl COA and
Krebs Cycle is worth 3 ATP (8 x 3 = 24)
o Each FADH2 is worth 2 ATP (2 x 2 = 4)
Net Energy Production: 36 ATP!
**Basic Notes and pictures obtained from the following link:
http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect12.htm