Download Pyruvate to ACETYL coA CC

Lactic Acid Dehydrogenase
Pyruvic Acid Dehydrogenase Complex
Pyruvate to ACETYL coA
CC‐CoA + CO2
• Mitochondria
3 carbon Pyruvate to 2 carbon ACETYL Coenzyme A
Pyruvate  Acetyl CoA + CO2 + NADH + H+
CO2 to blood for excretion
Acetyl CoA  multiple fates
#1 oxidized in mitochondria via Krebs Cycle
#2 converted to fatty acid
#3 may be waisted but will not be wasted
3 FFA + glycerol  triglyceride  adipiose tissue
• Mitochondrial reactions
Citric Acid Cycle
• Requires oxygen
• 3 carbon Pyruvate or Lactate(from glycolysis) converted to 2 carbon acetyl‐ CoA (which enters Citric Acid Cycle) and 1 molecule of CO2 (which is a waste product that has to be excreted). NADH also produced
• Citric Acid Cycle consists of eight separate biochemical reactions that are directed by enzymes of mitochondrial matrix
– uses: Acetyl coA (from glycolysis or FFA) and oxaloacetate
to produce:
• hydrogen carrier molecules for entry into electron transport system (3 NADH and FADH2)
• 1 ATP from substrate • Oxaloacetate for use in same cycle again
• 2 molecules of CO 2 (which is a waste product that has to be excreted)
Pyruvate
In mitochondrial
matrix
3C
Key
Acetyl-CoA
Oxaloacetate
Carbon atom
Citrate
C
Malate
Isocitrate
6C
Fumarate
 Ketoglutarate 1C
Succinate
4C
Succinyl
+
4C
1C
Fig. 2-11, p. 29
Oxidative Phosphorylation
• ATP is synthesized using energy from electrons associated with NADH and FADH2
as they are transferred to O2
4H+ O2  2 H2O
• Two protein group process: electron transport system and ATP synthase
The ATP produced captures energy available in nutrients in a form that can be used by other cellular components to do “cell work”
Fig. 2-12, p. 31
1 Glucose
Cytosol
Glycolysis
2 NADH
2
2 Pyruvate
Mitochondrial matrix
Pyruvate
to acetate
2 NADH
2 Acetyl-CoA
6 NADH
2 turns
of citric
acid cycle
2
2 x 1.5 ATP/FADH2
3
10 x 2.5 ATP/NADH
Oxidative
phosphorylation
25
ATP
Total 32
ATP
2 FADH2
2 FADH2
Electron
transfer
10 NADH
Mitochondrial
inner membrane
Electron
transfer
Fig. 2-13, p. 32
Fatty Acid to Acetyl coA
•
•
What is a fatty acid?
Beta oxidation is the process by which fatty acids, in the form of
Acyl-CoA molecules, are broken down in mitochondria to generate
Acetyl-CoA,
a. Activation of fatty acids in the cytosol
b. Transport of fatty acids into mitochondria
a. Fatty acids are transported across the outer mitochondrial
membrane by carnitine-palmitoyl transferase I
b. They are then couriered across the inner mitochondrial
membrane by carnitine
c. Beta oxidation occurs in the mitochondrial matrix: Two-carbon
molecules acetyl-CoA are repeatedly cleaved from the fatty acid.
a) Acetyl-CoA can then enter the TCA cycle, which produces
NADH and FADH2.
b) NADH and FADH2 are subsequently used in the electron
transport chain to produce ATP
What is a fatty acid?
A fatty acid is a with a long unbranched carbon chain tail
Most naturally occurring fatty acids have a chain of four to 28 carbons.
The number of carbon atoms is usually even.
Pictured is a rough representation of a C16 fatty acid.
Activation: in cytolsol ATPADP + activated *C
on fatty acid
The acid and activated carbon are cleaved in a
series of reactions. End products of step of 1
cycle of beta oxidation are Acetyl CoA,
NADH+H+ and FADH2 and an activated fatty acid
that is 2 carbons shorter
ATP after 1 cycle
NADH+H+  2.5 ATP + 1 H2O
FADH2  1.5 ATP + 1 H2O
Acetyl CoA(KREBS CYCLE) 3 NADH+H+ , 1 FADH2 + 1ATP
• 3 NADH+H+  9ATP + 3 H2O
• 1 FADH2 2ATP + 1 H2O
• TOTAL = 10 ATP per Acetyl CoA entering Krebs Cycle
14 ATP produced, 1 spent , NET = 13
16C FATTY ACID
•
•
•
8 ACETYL CoA
7 NADH+H+
7 FADH2
(x 10 = 80 ATP)
(x 2.5 = 17.5 ATP)
(x 1.5 = 10.5 ATP)
_____________________________________
TOTAL 108 ATP – 1 for activation = NET 107 ATP
Amino Acid oxidation
•
transamination (or aminotransfer): reaction between an amino acid
and a keto acid
transminase
amino acid1 + ketoacid2  ketoacid1 + amino acid2
The former keto
acid is now a
nonessential
amino acid that
has the amino
group
The former amino
acid is now a keto
acid that can be
used in the Krebs
cycle
Deamination
•
Deamination is the process by which amino acids are broken down
there is an excess of protein intake. The amino group is removed
from the amino acid and converted to ammonia.
•
The rest of the amino acid is made up of mostly carbon and
hydrogen, and is recycled or oxidized for energy. Ammonia is toxic to
the human system, and enzymes convert it to urea or uric acid by
addition of carbon dioxide molecules urea cycle, which also takes
place in the liver. Urea and uric acid can safely diffuse into the blood
and then be excreted in urine.
Urea
cycle
deaminase
+