Oh where, Oh where
has 34molecules of ATP
gone????????
Only the Krebs cycle knows for
sure.
The energy produced from the "burning" of glucose is used to make
ATP. In chemistry this process is called the oxidation of glucose.
The purpose of cellular respiration is to make ATP. All cells use and
need ATP.
There are 3 parts to cellular respiration
3 Part of Respiration
I. Glycolysis
II. Kreb's Cycle
III. Electron Transport Chain
After glycolysis, pyruvic acid is shuttled to the mitochondrion to
extract the energy from this molecule and convert it to ATP. This is
done by stripping the remaining hydrogens from pyruvic acid or
pyruvate. There are two molecules of pyruvic acid so the Kreb's
cycle occurs twice. The hydrogens are used to reduce NAD and
FAD. In addition 3 molecules of carbon dioxide are released. The
Kreb’s cycle is located in the inner compartment of the
mitochondrion.
Summary of Krebs- Occurs in mitochondrion
2X’s
Pyruvate---> 3 CO2
6 CO2
1 ADP ---> 1 ATP
2 ATP
4 NAD ---> 4 NADH2
8 NADH2
1 FAD ---> 1 FADH2
2 FADH2
The hydrogen found on pyruvate will be used to
reduce NAD and FAD. Only one ADP is
phosphorylated at the substrate level or directly
by enzymes.
Step 1
Prepping step. Pyruvate is decarboxylated and also oxidized. The hydrogens are
used to reduced NAD. Technically not a
part of the Kreb’s cycle
Step 2
The acetyl group is attached to
oxaloacetic acid to form citric acid
Prepping partTechnically not an official step of the Kreb’s cycle
Step 2
Technically not an official step of the Kreb’s cycle
Step 3
Water is removed and then added back
in to make isocitric acid
Step 4
Isocitric acid will be oxidized and NAD
will be-come reduced. The new acid is
oxalosuccinic acid
Steps 3 and 4
Citric acid is isomerizes to make isocitric acid and then isocitric acid
is oxidized making oxaloacetic acid. This step reduces NAD
Step 5 Oxalosuccinic acid will be
decarboxylated as it is converted
to a-ketoglutaric acid. It now has
only 5 carbons. Second CO2 is
released.
Step 6 a-ketoglutaric acid will
be decarboxylated and at the
same time oxidized. NAD will
be reduced. Third CO2 is
released.
Step 5 Oxalosuccinic acid will be decarboxylated as it is
converted to a-ketoglutaric acid. It now has only 5 carbons.
Second CO2 is released.
Step 6 a-ketoglutaric acid will be decarboxylated and at the
same time oxidized. NAD will be reduced. Third CO2 is
released.
Step 7. The next step is rather
complicated. Succinyl-Co-A looses the
coenzyme Co-A and is hydrated.
Phosphate is added to GDP--->GTP
which in turns takes the phosphate and
gives it to ADP--->ATP.
Step 8. Succinic acid becomes
oxidized and FAD becomes
reduced.
Step 7. The next step is rather complicated. Succinyl-Co-A looses
the coenzyme Co-A and is hydrated. Phosphate is added to
GDP--->GTP which in turns takes the phosphate and gives it to
ADP--->ATP. This is known as substrate phosphorylation.
Step 8. Succinic acid becomes oxidized and FAD becomes reduced.
Step 9. Fumaric acid
becomes hydrated as water
is added to it.
Step 10.
The last step malic acid is
oxidized and NAD is reduced to
return to oxaloacetic acid and
start the cycle again
Step 9. Fumaric acid becomes hydrated as water is added to it.
Step 10. The last step malic acid is oxidized and NAD is reduced to
return to oxaloacetic acid and start the cycle again
Summary of Krebs- Occurs in mitochondrion
2X’s
Pyruvate---> 3 CO2
6 CO2
1 ADP ---> 1 ATP
2 ATP
4 NAD ---> 4 NADH2
8 NADH2
1 FAD ---> 1 FADH2
2 FADH2
The hydrogen found on pyruvate will be used to
reduce NAD and FAD. Only one ADP is
phosphorylated at the substrate level or directly
by enzymes.
The purpose of chemiosmosis is to extract the energy
found in NADH and FADH2 to make more ATP.
This involves the cristae. There are electron
transport chains that are used.
The electrons from the NADH and FADH2 are used
to move on the electron transport chain. As the
electrons move down the electron transport chain,
H+ ions are pumped across the membrane.
The electrons from one NADH can pump 6 H+ across
the membrane, but the electrons from FADH2 can
only pump 4 H+ across the membrane.
The outer compartment of the
mitochondria becomes positive and
the inside becomes negative like a
battery. This "battery" can do work.
The hydrogen ions can cross an F1
particle and make ATP.
It takes 2 H+ to cross the F1 particle to
provide enough energy to make ATP.
Because the electron transport chain
oxidizes NADH or FADH2 and uses
the energy to phosphorylate ADP, this
is also known as oxidative
phosphorylation.
8 NADH2 x 6 H
= 48 H+
2 FADH2(Krebs)x 4 H = 8 H+
2 FADH2(glyc.) X 4 H = 8 H+
64 H+
ATP Summary
64 H+ --> 32 ATP
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ATP can be made from other foods other than glucose.
I. Carbohydrates
a. Starch--> X's glucose molecules and now respired in
glycolysis
b. Sucrose--> glucose and fructose and now respired in
glycolysis
II. Fats/Lipids-> Glycerol and 3 fatty acids
Glycerol is converted to PGAL and respired in glycolysis.
The fatty acids are chopped into 2 carbon acetyl groups and
used in the Krebs or citric acid cycle.
III. Proteins--> amino acids
Once the amino acids are
produced, then the
amine group must be
removed. The left over
acid is then used at some
point in the Krebs cycle