After glycolysis, pyruvic acid is shuttled to the
mitochondrion to extract the energy from this
molecule and convert it to ATP. Stripping the
remaining hydrogens from pyruvic acid or
pyruvate does this. 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
Summary of KrebsOccurs in
mitochondrion
2X’s
Pyruvate---> 3 CO2
6CO2
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 FADH 2 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.
8 NADH2 x 6 H
= 48 H+
2 FADH2(Krebs)x 4 H = 8 H+
2 FADH2(glyc.) X 4 H = 8 H+
ATP Summary
64 H+
64 H+ --> 32 ATP
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