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Assessment Statements
Cellular Respiration
CORE
3.7.1 Define cell respiration.
3.7.2 State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP.
3.7.3 Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further
yield of ATP.
3.7.4 Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.
Biology 11
A. Allen
AHL
8.1.1 State that oxidation involves the loss of electrons from an element, whereas reduction involves a gain of electrons; and that oxidation frequently involves
gaining oxygen or losing hydrogen, whereas reduction frequently involves losing oxygen or gaining hydrogen.
8.1.2 Outline the process of glycolysis, including phosphorylation, lysis, oxidation and ATP formation.
8.1.3 Draw and label a diagram showing the structure of a mitochondrion as seen in electron micrographs.
8.1.4 Explain aerobic respiration, including the link reaction, the Krebs cycle, the role of NADH + H+, the electron transport chain and the role of oxygen
8.1.5 Explain oxidative phosphorylation in terms of chemiosmosis.
8.1.6 Explain the relationship between the structure of the mitochondrion and its function.
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http://fusionanomaly.net/mitochondria.html
Activation Energy
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:
C6H12O6 + 6O2 6H20 + 6CO2 + energy (36 ATP)
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An overview of Aerobic Cellular Respiration
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 ).
Can you find
Glycolysis?
5
6
1
Glucose
6-C
Coenzyme
Glycolysis I
1
•
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.
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
4
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
X2
G3P
AKA G3P
G3P
AKA G3P
5
(3-C, 1 phosphate)
•
Pi
NADH
is formed). The oxidized G3P then accepts a
Pi from the cytosol. 1,3 bisphosphoglyerate
(3-C, 2 phosphates)
ADP
(BPG) is formed
ATP
2. ADP is phosphorylated to ATP (x2) as it
removes the phosphate from the substrate.
3-phosphoglycerate is formed. (substrate
level phosphorylation: when ADP removes
Pi from the substrate to form ATP)
3-phosphoglycerate
(3-C, 1 phosphate)
X2
In Glycolysis II, each G3P (2 from 1 molecule
of glucose) is oxidized to release energy. This
process is exergonic.
Substrate Level Phosphorylation
1. G3P is oxidized. NAD takes electrons (NADH
1,3 bisphosphoglycerate (BPG)
2
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Glycolysis II
G3P
(3-C, 1 phosphate)
1
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.)
Animation
NAD+
Glycolysis I is a series of endergonic
reactions
Glucose ~P
“glucose-6-phosphate”
6-C, 1 Phosphate
DHAP
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2
2-phosphoglycerate
(3-C, 1 phosphate)
• The direct phosphate transfer of
phosphate from an organic molecule to
ADP.
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
4
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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Think Together!
Vocabulary GAME!
Partners `A` and `B` take turns answering the
questions below.
•
•
•
•
•
•
•
•
•
A. What is the basic difference between Glycolysis I and
Glycolysis II?
B. What is the role of NAD?
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Glucose
fructose
G3P
Pyruvate
phosphate
Glucose-6 phosphate
NADH
ADP
endergonic
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2
• Decarboxylation-removal of a carboxyl
group
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Circle the end products of glycolysis. Where do they go next?
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Pyruvate Oxidation (IB calls this the ‘Link Reaction’)
Pyruvate
(pyruvic acid)
(3-C)
+
NAD
NADH
1
CO2
Acetate
(Acetic acid )
(2-C)
2
X2
Coenzyme A
(or ‘CoA’)
acetyl coenzyme A
(or ‘acetyl coA’)
2.
Animation
Pyruvate Oxidation
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)
Acetic acid combines with coenzyme
A to form acetyl coenzyme A.
A.
**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
1.
Animation
acetyl coenzyme A
(or ‘acetyl coA’)
Coenzyme A
(or ‘CoA’)
1
2.
Oxaloacetate (4-C)
3.
Citrate (6-C)
2
Isocitrate (6-C)
X2
NAD
3
4.
NADH
CO2
α -ketoglutarate (5-C)
Co
Co--A
CO2
Co
Co--A
Succinate
5
(4-C )
NAD
Succinyl--CoA
Succinyl
(4-C )
GTP GDP + Pi
NADH
4
5.
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
Can you find Pyruvate oxidation? Where does it occur?
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ATP
18
3
Krebs
Cycle
6.
Animation
acetyl coenzyme A
(or ‘acetyl coA’)
Coenzyme A
(or ‘CoA’)
1
8
7.
Oxaloacetate (4-C)
Citrate (6-C)
NADH
7
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
5
(4-C )
NAD
Succinyl--CoA
Succinyl
(4-C )
GTP GDP
ADP + Pi
4
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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ATP
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Think Together!
• Why is there a “X2” on the diagram of the
Krebs Cycle?
• Krebs cycle only yields 2 ATP per
molecule of glucose, but it also results in 6
NADH and 2 FADH2 produced. What do
you think NADH and FADH2 is for?
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Oxidative Phosphorylation (Electron Transport Chain)
…Oxidative Phosphorylation (Electron Transport Chain)
Animation #1
Animation #1
Animation #2
Animation #2
1
•
The electron transport chain is located on the inner membrane of the mitochondrion.
It consists of several electron carriers which accept electrons from NADH and
FADH2 (from glycolysis and Krebs cycle). It requires O2!
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2
[1] Energized electrons from Glycolysis and Krebs cycle are carried to the electron
transport chain via NADH...
[2] ...and FADH2
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4
…Oxidative Phosphorylation (Electron Transport Chain)
…Oxidative Phosphorylation (Electron Transport Chain)
Cytochrome c oxidase complex (H+ pump)
Cytochrome c oxidase complex (H+ pump)
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3
4
Animation #1
4
Animation #1
Animation #2
Animation #2
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NADH Dehydrogenase
NADH Dehydrogenase
2
1
(H+ pump)
6
2
1
(H+ pump)
5
Cytochrome bc1 complex (H+ pump)
Cytochrome bc1 complex (H+ pump)
[3] Electrons are passed through a series of electron carriers which become reduced/oxidized
as they pass off the electrons [complexes I -IV]. At different places along this chain, the
energy released from the electrons is used to ‘pump’ protons (H+) across the inner
membrane of the mitochondrion into the intermembrane space
[4] This creates a concentration gradient in the intermembrane space.
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[5] The H+ ions are allowed to pass back into the matrix through ATP synthase.
[6] Using the energy from the flow of protons, ADP is united with Pi to form ATP.
Note that because NADH and FADH2 enter the electron transport chain at different locations,
they yield different amounts of ATP; NADH yields 3 ATP and FADH2 yields 2 ATP.
[7] The electrons unite with protons (H+) and oxygen at the end of the ETC to form water.
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If insufficient O2 is available in the cell, the ETC will not work! What happens then?......
Electron Transport and
Chemiosmosis
Electron Transport and
Chemiosmosis
Fig. 9.15
H+
Cyt C
CoQ
CoQ
NAD+
NADH
H+
NAD+
NADH
H+
H+
H+
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Electron Transport and
Chemiosmosis
H+
H+
H+
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Electron Transport and
Chemiosmosis
Fig. 9.15
H+
Fig. 9.15
H+
oxidase complex
Cyt C
CoQ
H+
NAD+
Cytochrome c
oxidase complex
Cyt C
NADH
H+
H+
Cytochrome c
H+
CoQ
H+
NADH
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H+
NAD+
2 H+
+ ½ O2
Electron transport chain
H20
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chemiosmosis
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Smokin’ Chemiosmosis & Electron
Transport Animations
Electron Transport and
Chemiosmosis
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
• http://vcell.ndsu.nodak.edu/animations/atp
gradient/movie.htm
• http://vcell.ndsu.nodak.edu/animations/etc/
movie.htm
H+
NADH
H+
NAD+
2 H+
+ ½ O2
H20
ADP + P
ATP
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Can you see why FADH2 & NADH end in different ATP yields?
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Cyanide Blocks the Electron
Transport Chain
• Cyanide is a poison that inhibits
cytochrome oxidase activity. Why can
cyanide cause death?
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37
Summary of Aerobic Cellular Respiration
6
Structural Formula of ATP
• Label the diagram
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39
Net Energy Yield of Aerobic
Respiration
Anaerobic vs. Aerobic Respiration
•
NOTE: What happens after glycolysis depends on whether or not
oxygen is present…
ATPs
NADHs
FADH2s
ATPs From
ETC
Total ATPs
If O2 is absent….
Glycolysis
A
2
B
2
C0
D4
E6
Pyruvate
(Pyruvic Acid)
(3-C)
Pyruvic Acid
Oxidation
F0
G
2
H0
I6
J6
Total
2
K
P4
L6
10
Q
2
M
R2
22
N
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S
Pyruvate Goes to the Kreb’s
cycle in the mitochondria
(aerobic
respiration) for complete
oxidation.
NADH
X2
NAD+
Krebs Cycle
If O2 is present….
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O
lactate
(lactic acid)
fermentation
Lactate
(Lactic acid)
(3-C)
36
T
Lactic acid
(animals)
Once thought to
make muscles
fatigued after
Strenuous exercise)
41
Think Together!
This process is
called …
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Alcoholic Fermentation (in yeast)
With your partner, discuss:
• Does lactic acid fermentation yield any
energy?
• Assume the energy demands within a cell
greatly exceeds the body’s ability to
deliver oxygen. What is the point of
pyruvic acid being converted to lactic
acid? HINT: NAD is a limited commodity in
the cell.
•
An anaerobic step that yeast use after glycolysis that breaks down pyruvate to
ethanol (aka ethyl alcohol) and carbon dioxide.
Pyruvate
(Pyruvic Acid)
(3-C)
C02
Acetaldehyde
(2-C)
NADH
X2
NAD+
Ethanol
(the alcohol found in beer, wine, etc.)
(2-C)
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Alternate Pathways
•
•
Protein Catabolism
Carbohydrates are your body’s nutrient of choice.
Proteins lipids and nucleic acids can also be used.
•
•
•
•
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Proteins are made of different
types of amino acids.
The amino groups of amino
acids are removed
(deamination).
What remains of the amino
acids are then converted to
various components of
glycolysis or Krebs i.e.
pyruvate, acetyl CoA, alpha
ketoglutarate.
You know the rest!
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Lipid Catabolism
• Triglycerides are made of
glycerol and fatty acids.
Your digestive system breaks
triglycerides into these
components.
• Glycerol may be converted
into glucose via
gluconeogenesis or to DHAP
(what’s next…?)
• The fatty acids enter the
matrix and undergo beta
oxidation (acetyl groups are
removed from the fatty acids
and combine with CoA to form
Acetyl CoA…
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