Podcast
Questions and Answers
Where does fatty acid oxidation occur in most eukaryotes?
Where does fatty acid oxidation occur in most eukaryotes?
What is the final product of thiolytic cleavage in the β-oxidation of odd-chain fatty acids?
What is the final product of thiolytic cleavage in the β-oxidation of odd-chain fatty acids?
What is the energy yield of fatty acid oxidation compared to glucose oxidation?
What is the energy yield of fatty acid oxidation compared to glucose oxidation?
How many molecules of acetyl CoA are produced from the β-oxidation of stearate (18 C)?
How many molecules of acetyl CoA are produced from the β-oxidation of stearate (18 C)?
Signup and view all the answers
What is the intermediate formed during the conversion of propionyl CoA in mammals?
What is the intermediate formed during the conversion of propionyl CoA in mammals?
Signup and view all the answers
Which type of fatty acid chains are usually synthesized by bacteria and some organisms?
Which type of fatty acid chains are usually synthesized by bacteria and some organisms?
Signup and view all the answers
What is the process known as when the β-carbon unit (C-3) of the FA is being oxidized?
What is the process known as when the β-carbon unit (C-3) of the FA is being oxidized?
Signup and view all the answers
What is produced during the oxidation of fatty acids and is utilized in the electron transport chain?
What is produced during the oxidation of fatty acids and is utilized in the electron transport chain?
Signup and view all the answers
What is the byproduct of the final step of β-oxidation?
What is the byproduct of the final step of β-oxidation?
Signup and view all the answers
Where does β-oxidation occur in eukaryotes?
Where does β-oxidation occur in eukaryotes?
Signup and view all the answers
What is the enzyme that catalyzes the formation of a double bond between C2 and C3 atoms of the acyl group?
What is the enzyme that catalyzes the formation of a double bond between C2 and C3 atoms of the acyl group?
Signup and view all the answers
What is the product of the hydration step of β-oxidation?
What is the product of the hydration step of β-oxidation?
Signup and view all the answers
What is the electron carrier that receives electrons from acyl-CoA dehydrogenase?
What is the electron carrier that receives electrons from acyl-CoA dehydrogenase?
Signup and view all the answers
What is the acetyl-CoA used for in organisms that have the glyoxylate pathway?
What is the acetyl-CoA used for in organisms that have the glyoxylate pathway?
Signup and view all the answers
What is the role of fatty acid synthase inhibitors in mice?
What is the role of fatty acid synthase inhibitors in mice?
Signup and view all the answers
What is the function of lipoprotein lipase in triacylglycerol metabolism?
What is the function of lipoprotein lipase in triacylglycerol metabolism?
Signup and view all the answers
What is the precursor of steroid hormones and bile salts in mammals?
What is the precursor of steroid hormones and bile salts in mammals?
Signup and view all the answers
What is the result of inhibiting fatty acid synthase, at least in part?
What is the result of inhibiting fatty acid synthase, at least in part?
Signup and view all the answers
What is the function of β-oxidation in fatty acid metabolism?
What is the function of β-oxidation in fatty acid metabolism?
Signup and view all the answers
What is the role of chylomicrons in lipid transport?
What is the role of chylomicrons in lipid transport?
Signup and view all the answers
What is the source of all carbon atoms of cholesterol?
What is the source of all carbon atoms of cholesterol?
Signup and view all the answers
What is the fate of glycerol released from triacylglycerol hydrolysis?
What is the fate of glycerol released from triacylglycerol hydrolysis?
Signup and view all the answers
Study Notes
Fatty Acid Oxidation
- Fatty acid oxidation occurs in two stages: activation of fatty acid and degradation of 2-carbon units.
- It is also known as β-oxidation, as the β-carbon unit (C-3) of the fatty acid is being oxidized.
β-Oxidation Process
- First step: Oxidation
- Acyl-CoA dehydrogenase catalyzes the formation of a double bond between C2 and C3 atoms of the acyl group, forming trans 2-enoyl CoA.
- Electrons from fatty acyl CoA are transferred to acyl CoA dehydrogenase electron-transferring flavoprotein (ETF) and then to ubiquinone (QH2).
- Second step: Hydration
- Water is added to trans 2-enoyl CoA, forming L-3-Hydroxyacyl CoA, catalyzed by 2-enoyl-CoA hydratase.
- Third step: Oxidation
- L-3-Hydroxyacyl CoA dehydrogenase catalyzes the formation of 3-ketoacyl CoA, using NAD+.
- NADH is used in the electron transport chain.
- Final step: Thiolysis
- The nucleophilic sulfhydryl group of HS-CoA attacks the carbonyl carbon of 3-ketoacyl CoA, releasing acetyl CoA and a fatty acid shorter by 2 carbons.
ATP Generation from Fatty Acid Oxidation
- Fatty acid oxidation supplies more energy than glucose oxidation.
- For example, stearate (18 C) is converted to stearoyl CoA using 2 ATP, and 9 molecules of acetyl CoA enter the TCA cycle, generating 10 ATP each through 8 cycles of β-oxidation.
β-Oxidation of Odd-Chain and Unsaturated Fatty Acids
- Most fatty acids have an even number of carbon units, but some bacteria and organisms synthesize odd-chain fatty acids.
- These fatty acids are oxidized the same way as even-chain fatty acids, except the final product of the thiolytic cleavage is propionyl CoA (CoA with C3 acyl group) rather than acetyl CoA.
- Propionyl CoA can be converted to succinyl CoA in mammals.
Lipid Transport and Synthesis
- Lipid digestion products are absorbed by the intestinal mucosa and converted to triacylglycerol, which is packed into lipoprotein particles called chylomicrons.
- Triacylglycerols synthesized by the liver are packed into very low-density lipoproteins (VLDL) and released into the blood.
- The triacylglycerol components of chylomicrons and VLDL are hydrolyzed to fatty acids and glycerol in the capillaries of adipose tissue and skeletal muscle by lipoprotein lipase.
Cholesterol Synthesis
- Steroid cholesterol is an essential component of many membranes and a precursor of steroid hormones and bile salts.
- All carbon atoms of cholesterol come from acetyl CoA.
- The stages of the cholesterol biosynthesis pathway involve the synthesis of cholesterol from acetyl CoA.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Learn about the two stages of fatty acid oxidation, activation and degradation, and the β-oxidation process, including the oxidation step and enzyme catalysis. Understand how fatty acyl CoA is converted to trans 2-enoyl CoA.
