Download Lecture 10

Goals
Lecture 10:
Chemistry of Metabolism
• Understand basics of how different
foods are turned into energy
Nutrition 150
• DO NOT memorize complex reaction
chains
Shallin Busch, Ph.D.
• Understand why fats are more energy
dense than proteins and
carbohydrates
Catabolic Reactions
Anabolic Reactions
ANABOLIC REACTIONS
CATABOLIC REACTIONS
Glycogen
Uses
energy
Triglycerides
Uses
energy
Glucose
+
Glucose
Glycerol
Protein
Uses
energy
+
Fatty acids
Amino acids
+ Amino acids
Glycogen
Glucose
Yields
energy
Anabolic reactions require energy and combine
simple compounds into complex compounds.
Triglycerides
Glycerol
Yields
energy
Protein
Fatty acids
Yields
energy
Amino acids
Yields
energy
Catabolic reactions release energy and break large
molecules into smaller one.
Coenzymes
Coenzymes: Complex organic molecules
that work with enzymes to facilitate
the enzyme’s activity.
Transfer of Energy by ATP
Uses
energy
ADP + P
Energy from food is
used to attach a
phosphate group to
adenosine diphosphate
(ADP), making ATP.
Yields
energy
ATP
ATP captures and
stores this energy.
ADP + P
Energy from ATP is
released when a
phosphate bond is
broken. This energy
fuels the body’s work.
ATP is a high energy compound used to 1) store
energy and 2) yield energy
Adenosine Triphosphate (ATP)
Generating ATP
• ATP can be made when breaking down
food directly
Adenosine
+
3 phosphate groups
• ATP can also be made by the
“electron transport chain”, the
process by which the energy in free
electrons is captured as ATP.
Requires oxygen, makes water and
carbon dioxide.
Aerobic Catabolism of Glucose
Pyruvate
Acetyl CoA
The TCA Cycle
Glucose
Aerobic:
Reaction using
oxygen
(from carbon
dioxide)
Uses energy
(ATP)
Oxaloacetate
Coenzyme
Coenzyme
Coenzyme
Yields energy
(ATP)
Coenzyme
Coenzyme
2 Pyruvate
CoA
Coenzyme
Coenzyme
To Electron
Transport
Chain
Coenzyme
Coenzyme
Coenzyme
Coenzyme
Coenzyme
Coenzyme
2 CoA
Coenzyme
Coenzyme
Coenzyme
To Electron
Transport
Chain
Coenzyme
Coenzyme
Coenzyme
2 Carbon
dioxide
Yields energy
(captured in high-energy
compound similar to ATP)
To TCA Cycle
Glucose
Coenzyme
16-C fatty acid
Glucose returns to
the muscles
Coenzyme
Coenzyme
Glucose
Uses energy
(ATP)
CoA
Coenzyme
Uses energy
(ATP)
Coenzyme
Lactic acid travels
to the liver
2 Pyruvate
To Electron
Transport
Chain
In the liver:
Coenzyme
Yields energy
(ATP)
(as carbon
dioxide)
Catabolism of Fatty Acid
Anaerobic Catabolism of Glucose
In the muscle:
Coenzyme
To Electron
Transport
Chain
CoA
CoA
2 Acetyl CoA
(as carbon
dioxide)
CoA
2 Lactic acid
Coenzyme
Coenzyme
Anaerobic:
Reaction which doesn’t use oxygen
Coenzyme
CoA
Coenzyme
To Electron
Transport
Chain
Catabolism of a Triglyceride
Metabolism of Fatty Acid
CoA
+
CoA
To TCA
Cycle
Glucose
Net result from a 16-C fatty acid: 14-C fatty acid CoA +
1 acetyl CoA
Cycle repeats, leaving:
12-C fatty acid CoA
+
2 acetyl CoA
Cycle repeats, leaving:
10-C fatty acid CoA
+
3 acetyl CoA
Cycle repeats, leaving:
8-C fatty acid CoA
+
4 acetyl CoA
Cycle repeats, leaving:
6-C fatty acid CoA
+
5 acetyl CoA
Cycle repeats, leaving:
4-C fatty acid CoA
+
6 acetyl CoA
+
7 acetyl CoA
Cycle repeats, leaving:
2-C fatty acid CoA
Glycerol
Fatty acids
Pyruvate
CoA
CoA
Carbon
dioxide
Coenzyme
CoA
Co
CoA
Acetyl CoA
A
Coenzyme
Co
Co
A
Co
A
Co
Co
A
A
CoA
To TCA Cycle
Pyruvate
Acetyl CoA
(from carbon
dioxide)
The TCA Cycle
CoA
CoA
Oxaloacetate
Coenzyme
Ketone Body Formation from Fatty Acids
Acetyl CoA
Coenzyme
+
CoA
Acetyl CoA
2 CoA
OH
Coenzyme
Coenzyme
Coenzyme
Coenzyme
Coenzyme
Coenzyme
Coenzyme
Coenzyme
(as carbon
dioxide)
A ketone, acetoacetate
CO2
Coenzyme
To Electron
Transport
Chain
Yields energy
(captured in high-energy
compound similar to ATP)
(as carbon
dioxide)
To Electron
Transport
Chain
A ketone, acetone
+
H2O
A
To Electron
Transport
Chain
Catabolism of Amino Acids
Pyruvate
Amino acids
Acetyl CoA
(from carbon
dioxide)
Pyruvate
CoA
Coenzyme
Carbon
dioxide
CoA
Oxaloacetate
Coenzyme
Coenzyme
The TCA Cycle
Coenzyme
Coenzyme
To Electron
Transport
Chain
Coenzyme
Coenzyme
Coenzyme
Coenzyme
CoA
Acetyl CoA
Coenzyme
Coenzyme
Coenzyme
Coenzyme
To TCA Cycle
Coenzyme
To Electron
Transport
Chain
Yields energy
(captured in high-energy
compound similar to ATP)
Urea Excretion
Figure 7-17
Page 229
Amino acids
When an amino
acid is used for
energy, the
amine (NH3)
group is
disposed of as
urea.
Bloodstream
Ammonia
(NH3)
+
CO2
Liver
(as carbon
dioxide)
(as carbon
dioxide)
To Electron
Transport
Chain
Fatty Acids can generate more energy than Glucose
WHY?
Fatty acid
Urea
Bloodstream
Kidney
Urea
Glucose
Adding oxygen to carbon atoms yields energy
To bladder and
out of body
Feasting
Starving
Ketosis suppresses the appetite
Metabolism slows during starvation
Fasting