Download Cellular Respiration (Glycolysis, Pyruvate Ox, Krebs Only)

Cellular Respiration
Cellular Respiration
• Cellular respiration is…
The process by which a cell breaks down sugar or
other organic compounds to release energy used for
cellular work; may be anaerobic or aerobic,
depending on the availability of oxygen. Aerobic
respiration can be summarized by the following
formula:
Biology 11
A. Allen
C6H12O6 + 6O2 6H20 + 6CO2 + energy (36 ATP)
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http://fusionanomaly.net/mitochondria.html
Activation Energy
Glycolysis
• Glycolysis is the first stage of cellular respiration.
• Glycolysis has two parts; Glycolysis I & Glycolysis II. In order to
‘kick-start’ glycolysis I, activation energy is required (ATP).
Sugar is split into two G3Ps. In glycolysis II, G3P is oxidized and
ATP is produced. The overall pathway gets its name from this
sugar splitting (glyco = sugar, lysis = split).
• Glycolysis occurs in the cytosol (The fluid portion of the
cytoplasm, outside the organelles ).
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Glucose
6-C
Coenzyme
Glycolysis I
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•
ATP
ADP
• A substance that enhances or is
necessary for the action of enzymes. They
are generally much smaller than enzymes
themselves. NAD (Nicotinamide adenine
dinucleotide) is a coenzyme that serves
and an electron carrier.
Glycolysis I is a series of endergonic
reactions
Glucose ~P
“glucose-6-phosphate”
6-C, 1 Phosphate
1. Glucose enters the cell by diffusion
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2. ATP donates a phosphate to the substrate.
(1 ATP used) Glucose-6-phosphate is
produced.
Fructose~P
“fructose-6-phosphate”
6-C, 1 Phosphate
3. Glucose-6-phosphate is rearranged to
fructose-6-phosphate (another 6-C sugar)
ATP
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4. another ATP donates its phosphate (1 ATP
used). Fructose 1,6-bisphosphate is
produced.
ADP
P~ Fructose ~P
“Fructose 1,6-bisphosphate”
6-C, 2 Phosphates
DHAP
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2
X2
G3P
AKA G3P
Animation
G3P
AKA G3P
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(3-C, 1 phosphate)
5. The fructose 1,6 bisphosphate molecule is
split into 2 G3Ps (glyceraldehyde 3phosphate), a 3-carbon compound. Note
G3P is also known as glyceraldehyde 3phosphate (G3P)
**Glycolysis I …**
•2 ATP (2 ATP’s are used.)
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Glycolysis II
G3P
•
(3-C, 1 phosphate)
NAD+
1
Pi
NADH
(3-C, 2 phosphates)
ADP
is formed). The oxidized G3P then accepts a
Pi from the cytosol. 1,3 bisphosphoglyerate
(BPG) is formed
ATP
2. ADP is phosphorylated to ATP (x2) as it
3-phosphoglycerate
(3-C, 1 phosphate)
X2
Substrate Level Phosphorylation
1. G3P is oxidized. NAD takes electrons (NADH
1,3 bisphosphoglycerate (BPG)
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In Glycolysis II, each G3P (2 from 1 molecule
of glucose) is oxidized to release energy. This
process is exergonic.
2-phosphoglycerate
(3-C, 1 phosphate)
removes the phosphate from the substrate.
3-phosphoglycerate is formed. (substrate
level phosphorylation: when ADP removes
Pi from the substrate to form ATP)
• The direct phosphate transfer of
phosphate from an organic molecule to
ADP.
IMPORTANT!
3. 3-phosphoglycerate is rearranged to 2-
3
phosphoglycerate which is then rearranged
to phosphoenolpyruvate (PEP). Water is
given off in this process.
H2O
phosphoenolpyruvate
(PEP)
ADP
4. PEP gives a phosphate to ADP to make ATP.
Pyruvate (AKA Pyruvic acid) is formed.
ATP
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Pyruvate (Pyruvic Acid)
(3-C, 0 phosphates)
Animation
**Glycolysis results in a net gain of …**
•2 ATP (2 ATP’s are used and 4 are produced)
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•2 NADH These hydrogens are transported
to the mitochondria for more ATP production
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Pyruvate Oxidation (Pyruvic Acid Oxidation)
Pyruvate
(pyruvic acid)
(3-C)
+
NAD
• Decarboxylation-removal of a carboxyl
group
NADH
Remember, in glycolysis, glucose was
oxidized to 2 pyruvate molecules.
Therefore, the above biochemical pathways
run twice for every molecule of glucose!
Pyruvate Oxidation ONLY HAPPENS IF O2
is present!
1.
The two pyruvate from glycolysis
diffuse into the mitochondrion’s
matrix. Here, it is oxidized by NAD+
(which is reduced to NADH
NADH)) to make
acetate,, a 2acetate
2-carbon compound. (The
carbon is lost in the form of CO2)
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CO2
Acetate
(Acetic acid )
(2-C)
2
X2
Coenzyme A
(or ‘CoA’)
acetyl coenzyme A
(or ‘acetyl coA’)
Animation
**Pyruvate Oxidation results in a net gain of …**
•2 NADH. These hydrogens are transported to the
Electron Transport Chain for more ATP production
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Krebs
Cycle
Pyruvate Oxidation
Acetic acid combines with coenzyme
A to form acetyl coenzyme A.
A.
2.
1.
Animation
acetyl coenzyme A
(or ‘acetyl coA’)
Coenzyme A
(or ‘CoA’)
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2.
Oxaloacetate (4-C)
3.
Citrate (6-C)
2
Isocitrate (6-C)
X2
NAD
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4.
NADH
CO2
α -ketoglutarate (5-C)
Co
Co--A
CO2
Co
Co--A
Succinate
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(4-C )
NAD
Succinyl--CoA
Succinyl
(4-C )
GTP GDP + Pi
NADH
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5.
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Acetyl coenzyme A enters the
Krebs cycle and combines with
Oxaloacetate (4-C), to make
citrate (6-C). Coenzyme A is
recycled for further use.
Citrate is rearranged to isocitrate
(6-C)
NAD accepts hydrogens from
isocitrate which is therefore
oxidized. One molecule of CO2 is
given off as isocitrate loses one
carbon. α-ketoglutarate (5-C) is
formed.
α -ketoglutarate (5-C) is oxidized
to succinyl Co-A (4-C). A CO2 is
removed, coenzyme A is added,
and 2 hydrogen atoms reduced
NAD to NADH. Succinyl C0-A is
produced.
Succinyl Co-A (4-C) is converted
to succinate (4-C). A Pi from the
matrix displaces C0-A from
succilyl Co-A. The phosphate is
then tansfered to GDP (guanosine
diphosphate) to make GTP. Then
the Pi is transferred to ADP to
make ATP!
ADP + Pi
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ATP
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2
Krebs
Cycle
6.
Animation
acetyl coenzyme A
(or ‘acetyl coA’)
Coenzyme A
(or ‘CoA’)
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7.
Oxaloacetate (4-C)
Citrate (6-C)
NADH
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8.
2
NAD
malate (4-C)
Isocitrate (6-C)
X2
H20
NAD
3
NADH
CO2
fumarate (4-C)
Succinate (4-C) is oxidized to
fumarate (4-C). Not enough
energy is released to reduce
NAD, so FAD is instead
reduced to FADH2.
Fumarate (4-C) is converted
to malate (4-C).
Malate is oxidized to
oxaloacetate (4-C). 2
hydrogens are reduced NAD
to NADH. Oxaloacetate has
been restored, so the cycle can
continue! Yahoo!
α ketoglutarate (5-C)
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FADH2
FAD
Co
Co--A
CO2
Co
Co--A
Succinate
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(4-C )
NAD
Succinyl--CoA
Succinyl
(4-C )
GTP GDP
ADP + Pi
ATP
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Only 2 ATP’s have been
produced from Krebs
cycle. NADH
Final products of Krebs Cycle per molecule of glucose:
3 x 2 = 6 NADH (to electron transport chain to make ATP)
ATP)
1 x 2 = 2 FADH2 (to electron transport chain to make ATP)
ATP)
1 x 2 = 2 ATP
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