Introduction to Biochemistry and Molecular Biology
BCMB 3100 31276
Lipid Metabolism
Take-HomePoint
Like glycolysis and gluconeogenesis, other metabolic pathways are governed by principles we learned
in Unit 2. For example, enzymes in the pathways are highly regulated, and enzyme-mediated
regulatory mechanisms allow these pathways to be sensitive and responsive to the needs of the
organism. These pathways also illustrate how metabolism is linked to the energy status of cells,
consuming or generating energy in the form of molecules like ATP and NADH. Ultimately, these
metabolic pathways are integrated and connected. For example, the substrates and products of the
citric acid cycle are involved in gluconeogenesis, fatty acid synthesis, amino acid synthesis, and other
pathways.
Learning Objectives
1. State the functions of fatty acids, triacylglycerols, membrane phospholipids, and cholesterol.
2. Draw the chemical structures of fatty acids, triacylglycerols, and membrane phospholipids.
Recognize the structure of cholesterol.
3. Describe how fatty acids are activated and transported into the mitochondria for oxidation.
4. List the products of fatty acid oxidation.
5. Calculate the amount of ATP generated from a fatty acid of a particular length and compare this to
the amount of ATP generated from glucose.
6. Understand the different metabolic products from the oxidation of odd- and even-number fatty
acids
7. Describe the processes and locations of both the production and the catabolism of ketone bodies.
8. Describe a ketone body and how it can be used as fuel.
9. Draw a diagram that shows the connections between: glycolysis, gluconeogenesis, pyruvate to
acetyl-CoA, citric acid cycle, electron transport chain, fatty acid synthesis, fatty acid degradation,
and ketone body production.
10. Explain how Type 2 diabetes can shift fuel usage from carbohydrates to fats and how this impacts
the production of ketone bodies.
11. Predict how increased NADH impacts flux through glycolysis, gluconeogenesis, the citric acid cycle,
fatty acid oxidation, and fatty acid synthesis.
12. Explain how the products of ethanol metabolism can lead to liver disease and damage.
13. Describe the three stages of Fatty Acid Synthesis.
, 13. Explain how the acetyl CoA molecules, the raw material for Fatty acids synthesis, is transferred to
the cytoplasm from mitochondria?
14. Describe the reaction catalyzed by Acetyl CoA carboxylase and explain how phosphorylation affects
the activity of the Acetyl CoA carboxylase.
Part I – Fatty Acid Degradation
1. Describe the differences in fatty acids, triacylglycerols, and membrane lipids.
Fatty acids, triacylglycerols, and membrane lipids are all types of lipids, which are rich in
carbon and hydrogen, but contain little oxygen and are thus hydrophobic. Fatty acids are the
simplest lipids, as they are long hydrocarbon chains with a carboxylate group at one end. They
serve as a prominent fuel source and are a building block for membrane lipids. They can be
saturated or unsaturated, depending on the amount of C=C double bonds present.
Triacylglycerols serve as the storage form of fatty acids in adipocytes and are triesters made of
three fatty acids chains and one glycerol. Membrane lipids, including phospholipids, consist of
glycerol linked to a negatively charged phosphate group and two fatty acids. They are a major
part of the cell membrane as they are amphipathic with their hydrophilic head and hydrophobic
tails.
2. Draw a saturated triacylglycerol with 18 carbons (stearate) on each fatty acid chain. Show each carbon
as a “C”; hydrogens, “H,” may be written with subscripts. Insert a photo of your drawing below.
3. Enzymes called lipases hydrolyze triacylglycerols to yield fatty acids and glycerol. What molecule is
glycerol converted into so that it can enter glucose metabolism?
Glycerol in converted into glyceraldehyde 3-phosphate so that it can enter glucose
metabolism.
4. Using palmitate as an example (Ch 27.1 of your textbook), compare the energy generated by a
stearate to the energy generated by glucose.
a. Write the chemical reaction for activation of stearate (C18).
CH3(CH2)16COO- + CoA + ATP + H2O CH3(CH2)16CO-CoA + AMP + 2Pi
BCMB 3100 31276
Lipid Metabolism
Take-HomePoint
Like glycolysis and gluconeogenesis, other metabolic pathways are governed by principles we learned
in Unit 2. For example, enzymes in the pathways are highly regulated, and enzyme-mediated
regulatory mechanisms allow these pathways to be sensitive and responsive to the needs of the
organism. These pathways also illustrate how metabolism is linked to the energy status of cells,
consuming or generating energy in the form of molecules like ATP and NADH. Ultimately, these
metabolic pathways are integrated and connected. For example, the substrates and products of the
citric acid cycle are involved in gluconeogenesis, fatty acid synthesis, amino acid synthesis, and other
pathways.
Learning Objectives
1. State the functions of fatty acids, triacylglycerols, membrane phospholipids, and cholesterol.
2. Draw the chemical structures of fatty acids, triacylglycerols, and membrane phospholipids.
Recognize the structure of cholesterol.
3. Describe how fatty acids are activated and transported into the mitochondria for oxidation.
4. List the products of fatty acid oxidation.
5. Calculate the amount of ATP generated from a fatty acid of a particular length and compare this to
the amount of ATP generated from glucose.
6. Understand the different metabolic products from the oxidation of odd- and even-number fatty
acids
7. Describe the processes and locations of both the production and the catabolism of ketone bodies.
8. Describe a ketone body and how it can be used as fuel.
9. Draw a diagram that shows the connections between: glycolysis, gluconeogenesis, pyruvate to
acetyl-CoA, citric acid cycle, electron transport chain, fatty acid synthesis, fatty acid degradation,
and ketone body production.
10. Explain how Type 2 diabetes can shift fuel usage from carbohydrates to fats and how this impacts
the production of ketone bodies.
11. Predict how increased NADH impacts flux through glycolysis, gluconeogenesis, the citric acid cycle,
fatty acid oxidation, and fatty acid synthesis.
12. Explain how the products of ethanol metabolism can lead to liver disease and damage.
13. Describe the three stages of Fatty Acid Synthesis.
, 13. Explain how the acetyl CoA molecules, the raw material for Fatty acids synthesis, is transferred to
the cytoplasm from mitochondria?
14. Describe the reaction catalyzed by Acetyl CoA carboxylase and explain how phosphorylation affects
the activity of the Acetyl CoA carboxylase.
Part I – Fatty Acid Degradation
1. Describe the differences in fatty acids, triacylglycerols, and membrane lipids.
Fatty acids, triacylglycerols, and membrane lipids are all types of lipids, which are rich in
carbon and hydrogen, but contain little oxygen and are thus hydrophobic. Fatty acids are the
simplest lipids, as they are long hydrocarbon chains with a carboxylate group at one end. They
serve as a prominent fuel source and are a building block for membrane lipids. They can be
saturated or unsaturated, depending on the amount of C=C double bonds present.
Triacylglycerols serve as the storage form of fatty acids in adipocytes and are triesters made of
three fatty acids chains and one glycerol. Membrane lipids, including phospholipids, consist of
glycerol linked to a negatively charged phosphate group and two fatty acids. They are a major
part of the cell membrane as they are amphipathic with their hydrophilic head and hydrophobic
tails.
2. Draw a saturated triacylglycerol with 18 carbons (stearate) on each fatty acid chain. Show each carbon
as a “C”; hydrogens, “H,” may be written with subscripts. Insert a photo of your drawing below.
3. Enzymes called lipases hydrolyze triacylglycerols to yield fatty acids and glycerol. What molecule is
glycerol converted into so that it can enter glucose metabolism?
Glycerol in converted into glyceraldehyde 3-phosphate so that it can enter glucose
metabolism.
4. Using palmitate as an example (Ch 27.1 of your textbook), compare the energy generated by a
stearate to the energy generated by glucose.
a. Write the chemical reaction for activation of stearate (C18).
CH3(CH2)16COO- + CoA + ATP + H2O CH3(CH2)16CO-CoA + AMP + 2Pi
