▪
Substrate level phosphorylation:
forms ATP, b/c phosphate group transferred from ADP.
▪
At pyruvate:
o
If
aerobic:
goes to Krebs
→
broken into CO
2
o
If
anaerobic
: makes lactate
▪
Lactate is made by:
glucose + 2 ADP + 2 Pi
→
2 Lactate + 2 ATP + 2 H2O
o
In which 2 hydrogens transferred from NADH + H+ to pyruvate, NAD+ regenerates.
▪
Then lactate will either go to the blood function in heart and tissues and regenerate as
pyruvate or goes to liver to form glucose.
▪
If it is going to Krebs:
NADH + H+ will transfer to O2 during oxidative phosphorylation regenerating
NAD+ and producing H20.
▪
The
amount of ATP
produced by glycolysis (lactate) is
much smaller
than the ones that go into Krebs
and oxidative phosphorylation.
▪
Also, carbs such as fructose, galactose can perform glycolysis.
Krebs Cycle
▪
Involved in nutrient catabolism and ATP production
▪
Produces co2, hydrogen and small amounts of ATP.
▪
Molecule entering is
acetyl CoA
–
comes from pyruvate or breakdown of fatty acids/ AA.
▪
Enters the mitochondria from the
cytosol.
▪
Krebs only does aerobic because O.P. necessary for regeneration of hydrogen free coenzymes.
Entering Krebs:
Acetyl coA
Location:
Inner mitochondrial matrix
ATP
production:
1 GTP, can convert to ATP, only aerobic, (GTP +
ADP <--> GDP + ATP)
Coenzyme
prod:
3 NADH + 2 H+ 2 FADH2
Final Products:
2 CO2 for each acetyl coA
17
Net Reaction:
Acetyl coA + 3 NAD + FAD + GDP + Pi + 2 H2O
--->
2 CO2 + CoA + 3 NADH + 3 H+ + FADH2
+ GTP
Oxidative Phosphorylation
▪
Energy transfer from ATP is derived from
energy released when H
+
+ O
2
= H
2
O.
▪
From Krebs we have 3 NADH + 2 H
+
+ 2
FADH
—
these hydrogens are pumped in
system.
▪
Proteins either
—
transfer H
+
to O
2
or will
couple E release to synthesize ATP.
▪
These proteins will combine with cytochromes (proteins that have Fe and Cu factors) to transfer 2e-
to ETC.
▪
These 2e- are transferred to others in the chain to/from
cytochromes
until they are officially
transferred to O
▪
Energy is also released during the process
—
cytochromes use this to pump H+ into intermembrane
space.
o
The hydrogen ions flow down concentration gradient across inner mitochondrial
membrane through a channel by ATP synthase. ATP synthase takes this energy and
synthesizes ATP from ADP + P
i
. Maximum of 2-3 ATP produced per 1 e- donated.
o
Chemiosmosis:
process in which the inner mitochondrial matrix channel allows for H+
ions to flow back to matrix side.
▪
Finally, H
+
+ O
2
= H
2
O
→
Regenerates 2 H
+
→
used for glycolysis, Krebs & fatty acids.
▪
Regeneration of the H
+
free form of the coenzyme is aerobic
Carbohydrate Metabolism
▪
Found in Glycolysis, Krebs and O.P.
▪
Amount of E released is 686 kcal/mol and 40% of this energy is transferred to ATP.
▪
2 net ATP
→
phosphorylation in Glycolysis
▪
2 net ATP
→
Krebs
▪
34 ATP
→
Oxidative phosphorylation from generation of ATP.
