Questions and Answers
What is the primary reducing equivalent source for palmitate synthesis?
Which of the following conditions must be met for human fatty acid oxidase to function?
Which fatty acids must be supplied through the diet due to human limitations in synthesis?
What type of enzyme is fatty acid oxidase classified as?
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Which type of hydride ion donor is utilized in the synthesis of palmitate?
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Which of the following statements is true regarding human fatty acid metabolism?
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What is a dietary deficiency caused by the inability to synthesize polyunsaturated fatty acids?
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Why are linoleic and linolenic acids considered essential fatty acids for humans?
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Which reaction component is essential for both fatty acid synthesis and oxidation?
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What factor does NOT influence the extent of fluidity in membranes?
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Which fatty acids are more susceptible to oxidation?
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Where is the CoA portion of acetyl CoA primarily unable to pass, necessitating transport mechanisms?
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Which of the following is NOT a source of acetyl CoA in mammalian cells?
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What is a characteristic of branched-chain fatty acids in nature?
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What condition can result from the accumulation of phytanic acid in the plasma and tissues?
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Which statement regarding saturated fatty acids is accurate?
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What primarily affects the sensitivity of fatty acids to oxidation?
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Which statement is correct regarding enzyme location related to acetyl CoA?
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What is the role of phosphatase in the process of acylation?
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Which factor is necessary for the synthesis of TAG in adipose tissue?
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What is the primary source of glycerol 3-phosphate for TAG synthesis in adipose tissue?
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Why can't adipose tissue utilize certain pathways for TAG synthesis?
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What is required for the conversion of the keto group to an alcohol?
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What is the form in which TAG is stored in adipose tissue?
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Which enzyme catalyzes the dehydration reaction that introduces a double bond?
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Which hormonal condition is vital for glucose entry into adipocytes?
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What is produced after the second reduction in the fatty acid synthesis process?
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Which reaction involves the removal of a water molecule?
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Which of the following reactions is catalyzed by enoyl-ACP reductase?
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The initial substrate for the reduction process is:
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Which molecule is released during the conversion of 3-Hydroxybutyryl-S-ACP to crotonyl-S-ACP?
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What type of compound is produced at the end of the fatty acid synthesis process described?
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What is the role of NADPH in the reactions described?
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What is the function of 3-ketoacyl-ACP reductase in the alcohol formation process?
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What is the primary function of palmitate in fatty acid metabolism?
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Which statement accurately describes the endoplasmic reticulum system in fatty acid elongation?
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What is formed when palmitate undergoes elongation in the endoplasmic reticulum?
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What characteristic of TAGs contributes to their storage capability in adipocytes?
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In which cellular structures are the enzymes for the elongation of fatty acids primarily found?
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What is the primary source of carbon units for the mitochondrial elongation system?
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What role do fat deposits play in human metabolism?
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Which fatty acid is commonly produced during the elongation of palmitate?
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What characteristic do triglycerides possess that affects their solubility?
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How does the elongation process modify the chain length of fatty acids?
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Study Notes
Membrane Fluidity and Dietary Influence
- Fluidity of cell membranes is influenced by unsaturated fatty acids in lipids and dietary fat intake.
- Conversion of excess glucose to fatty acids is necessary for storage.
Sensitivity to Oxidation
- Saturated fatty acids are more resistant to oxidation in comparison to unsaturated fatty acids, which are prone to rancidification.
- Unsaturated fatty acids oxidize slowly in air, leading to potential rancidity.
Sources of Acetyl CoA
- Acetyl CoA is generated primarily in two locations:
- Cytosol: Produced from glucose oxidation via glycolysis.
- Mitochondria: The Acetyl CoA Shuttle System is utilized as CoA cannot cross the mitochondrial membrane.
- Generated through the oxidation of pyruvate or alcohol formation.
Branched-Chain Fatty Acids
- Examples include Phytanic Acid, which is found in dairy products.
- Accumulation in plasma and tissues can lead to disorders like Refsum’s disease due to inability to degrade this fatty acid.
Fatty Acid Synthesis Process
- Involves a series of enzymatic reactions:
- 3-Ketoacyl-ACP reductase converts keto groups to alcohol, requiring NADPH.
- Dehydration reaction introduces double bonds via 3-hydroxyacyl-ACP dehydratase, removing water.
- Enoyl-ACP reductase completes reduction, requiring NADPH to produce a fully saturated 4-carbon compound.
Role of NADH and Palmitate Production
- Cytosolic NADH, derived from glycolysis, aids in synthesizing palmitate, a key fatty acid.
- NADPH serves as a reducing equivalent in the fatty acid synthesis pathway.
Fatty Acid Oxidase
- A mixed-function oxidase that requires O2 and NADPH.
- Humans cannot introduce double bonds beyond carbons 9-10, necessitating a dietary intake of polyunsaturated fatty acids such as linoleic and linolenic acids.
Features of Palmitate
- Palmitate is a 16-carbon fully saturated fatty acid and is an end-product of fatty acid synthase activity.
- Can be elongated or desaturated through specific enzymatic pathways located in mitochondria and the endoplasmic reticulum.
Elongation Systems
- Fatty acids longer than 16-carbon chains are produced by adding 2-carbon units.
- Two systems are involved:
- Endoplasmic Reticulum System, which uses malonyl CoA for elongation.
- Mitochondrial Elongation System, utilizing acetyl CoA.
Tag Synthesis and Storage
- Triglycerides (TAGs) are synthesized in adipose tissues, relying on carbohydrate metabolism for glycerol formation.
- Adipose tissue lacks glycerol kinase, making DHAP the only source for glycerol 3-phosphate.
- Insulin is necessary for glucose entry into adipocytes, which is essential for TAG synthesis.
- TAGs serve as a depot fat in adipocytes, stored in an anhydrous form, ready for mobilization.
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Description
This quiz explores the properties of lipids, focusing on the role of unsaturated fatty acids in membrane fluidity and the sensitivity of fatty acids to oxidation. Enhance your understanding of how diet and fatty acid composition affect biological membranes.
