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Questions and Answers
What initiates the rate limiting step in fatty acid synthesis?
What initiates the rate limiting step in fatty acid synthesis?
Which component is essential for the activity of acetyl-CoA carboxylase?
Which component is essential for the activity of acetyl-CoA carboxylase?
How many carbon atoms does palmitate consist of, which is produced by fatty acid synthase?
How many carbon atoms does palmitate consist of, which is produced by fatty acid synthase?
Which metabolic pathway is a source of NADPH for fatty acid synthesis?
Which metabolic pathway is a source of NADPH for fatty acid synthesis?
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What is the structural characteristic of the fatty acid synthase complex?
What is the structural characteristic of the fatty acid synthase complex?
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Which of the following provides acetyl CoA for fatty acid biosynthesis?
Which of the following provides acetyl CoA for fatty acid biosynthesis?
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What is the primary function of malic enzyme in fatty acid synthesis?
What is the primary function of malic enzyme in fatty acid synthesis?
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During fatty acid synthesis, which of the following is increased by each cycle of the fatty acid synthase reaction?
During fatty acid synthesis, which of the following is increased by each cycle of the fatty acid synthase reaction?
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What role does acetyl CoA carboxylase play in fatty acid metabolism?
What role does acetyl CoA carboxylase play in fatty acid metabolism?
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During starvation, which hormone is primarily responsible for activating lipolysis in adipose tissues?
During starvation, which hormone is primarily responsible for activating lipolysis in adipose tissues?
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How does insulin affect acetyl CoA carboxylase activity?
How does insulin affect acetyl CoA carboxylase activity?
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What is the effect of palmitoyl CoA on acetyl CoA carboxylase?
What is the effect of palmitoyl CoA on acetyl CoA carboxylase?
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Which factor does NOT contribute to the activation of acetyl CoA carboxylase?
Which factor does NOT contribute to the activation of acetyl CoA carboxylase?
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Which statement accurately describes the short-term regulation of fatty acid synthesis?
Which statement accurately describes the short-term regulation of fatty acid synthesis?
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Which metabolic state results in increased malonyl CoA formation?
Which metabolic state results in increased malonyl CoA formation?
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What is the role of AMP in the global regulation of acetyl CoA carboxylase?
What is the role of AMP in the global regulation of acetyl CoA carboxylase?
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Which of the following statements about Acetyl CoA is true?
Which of the following statements about Acetyl CoA is true?
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Which enzyme is considered the rate limiting step in fatty acid synthesis?
Which enzyme is considered the rate limiting step in fatty acid synthesis?
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Where does the biosynthesis pathway for fatty acids primarily occur?
Where does the biosynthesis pathway for fatty acids primarily occur?
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What initiates the elongation phase during fatty acid synthesis?
What initiates the elongation phase during fatty acid synthesis?
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Which hormones are involved in the regulation of carboxylase activity?
Which hormones are involved in the regulation of carboxylase activity?
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What is the major building block for the synthesis of triacylglycerols in most tissues?
What is the major building block for the synthesis of triacylglycerols in most tissues?
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Which process occurs in adipose tissue to produce glycerol-3-phosphate?
Which process occurs in adipose tissue to produce glycerol-3-phosphate?
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What prevents the synthesis of triacylglycerols in adipocytes when glucose is low?
What prevents the synthesis of triacylglycerols in adipocytes when glucose is low?
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Which of the following describes the process of triacylglycerol synthesis?
Which of the following describes the process of triacylglycerol synthesis?
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What is the yield of energy from triglycerides compared to carbohydrates and proteins?
What is the yield of energy from triglycerides compared to carbohydrates and proteins?
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What is the role of Glycerol Kinase in triglyceride synthesis?
What is the role of Glycerol Kinase in triglyceride synthesis?
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Which component is produced from glucose through glycolysis that is essential for triacylglycerol synthesis?
Which component is produced from glucose through glycolysis that is essential for triacylglycerol synthesis?
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Which enzyme is responsible for the conversion of malonyl CoA to malonyl ACP?
Which enzyme is responsible for the conversion of malonyl CoA to malonyl ACP?
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During which step does the actual reduction of keto-acyl-ACP to hydroxyacyl-ACP occur?
During which step does the actual reduction of keto-acyl-ACP to hydroxyacyl-ACP occur?
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What is the byproduct of the condensation reaction in fatty acid synthesis?
What is the byproduct of the condensation reaction in fatty acid synthesis?
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What occurs during the dehydration step of fatty acid synthesis?
What occurs during the dehydration step of fatty acid synthesis?
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Which compound serves as the initial substrate in the fatty acid synthesis pathway?
Which compound serves as the initial substrate in the fatty acid synthesis pathway?
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What is the role of ACP (Acyl Carrier Protein) in the fatty acid synthesis process?
What is the role of ACP (Acyl Carrier Protein) in the fatty acid synthesis process?
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Which step involves the transfer of the acetyl group to ACP?
Which step involves the transfer of the acetyl group to ACP?
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What is the significance of the fatty acid synthase enzyme being coded by a single gene?
What is the significance of the fatty acid synthase enzyme being coded by a single gene?
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What initiates the elongation phase of fatty acid synthesis?
What initiates the elongation phase of fatty acid synthesis?
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Which enzyme catalyzes the conversion of acetoacetyl ACP to D-3-hydroxybutyryl ACP?
Which enzyme catalyzes the conversion of acetoacetyl ACP to D-3-hydroxybutyryl ACP?
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What is the product of the dehydration of D-3-hydroxybutyryl ACP?
What is the product of the dehydration of D-3-hydroxybutyryl ACP?
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Which reducing agent is used during the reduction of crotonyl ACP to butyryl ACP?
Which reducing agent is used during the reduction of crotonyl ACP to butyryl ACP?
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Which domain of the multifunctional enzyme complex contains the acyl carrier protein?
Which domain of the multifunctional enzyme complex contains the acyl carrier protein?
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What is the result of the final reaction in fatty acid synthesis involving palmitoyl-ACP?
What is the result of the final reaction in fatty acid synthesis involving palmitoyl-ACP?
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What type of reaction links acetyl ACP and malonyl ACP to form acetoacetyl ACP?
What type of reaction links acetyl ACP and malonyl ACP to form acetoacetyl ACP?
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Which enzyme is responsible for catalyzing the condensation of butyryl ACP with malonyl ACP?
Which enzyme is responsible for catalyzing the condensation of butyryl ACP with malonyl ACP?
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Study Notes
Fatty Acid Synthesis Overview
- Fatty acid synthesis is the creation of fatty acids.
- It primarily occurs in the cytoplasm of specialized cells like liver, adipose tissue, and lactating mammary glands.
- It is a crucial pathway for energy storage in the form of triglycerides.
Stages of Fatty Acid Synthesis
- Transport of Acetyl CoA: Acetyl CoA, a product of carbohydrate and amino acid breakdown, is exported from mitochondria into the cytoplasm via the citrate transport system.
- Carboxylation of Acetyl CoA: Acetyl CoA is converted to malonyl CoA by the enzyme acetyl CoA carboxylase. This is a critical, irreversible rate-limiting step in the entire synthesis process.
- Assembly of the Fatty Acid Chain: Fatty acid synthase (FAS), a multi-enzyme complex, catalyzes the elongation of the carbon chain by two carbons at a time. This involves a series of reactions including condensation, reduction, dehydration, and another reduction.
Requirements for Fatty Acid Synthesis
- Enzymes: Fatty acid synthase (FAS), a multi-enzyme complex, and acetyl-CoA carboxylase, also a multi-enzyme.
- Coenzymes and cofactors: Biotin, NADPH, and Mn++.
- CO2: bicarbonate, and ATP provide the carbon dioxide source and energy.
Sources of NADPH
- NADPH is created by transferring a molecule of acetyl CoA from mitochondria to the cytosol within the malic enzyme.
- The pentose phosphate pathway also contributes to NADPH production.
Regulation of Fatty Acid Synthesis
- Short-term regulation: Allosteric and/or metabolic regulation; covalent modification
- Long-term regulation: Acetyl CoA carboxylase (ACC), Fatty acid synthase (FAS), ATP-citrate lyase).
- Hormonal regulation: Insulin promotes synthesis while glucagon and epinephrine inhibit synthesis.
- Dietary regulation: Carbohydrate-rich diets promote synthesis, and prolonged periods with low glucose can reduce it.
- Allosteric regulation: Citrate stimulates and palmitoyl CoA inhibits acetyl CoA carboxylase.
Significance of Fatty Acid Synthase
- High efficiency of fatty acid production.
- Lack of permeability barriers.
- Single gene coding for good coordination of enzymes.
Synthesis of Triglycerides
- The major precursor for triacylglycerol synthesis, in tissues other than adipose tissue, is glycerol-3-phosphate.
- Adipocytes lack glycerol kinase, therefore dihydroxyacetone phosphate, produced during glycolysis, is their precursor for triacylglycerol synthesis.
- Adipocytes must oxidize glucose in order to store fatty acids.
Synthesis of Glycerol 3-Phosphate
- There are multiple pathways for the production of glycerol-3-phosphate, one dependent on glucose availability, the other independent.
Breakdown of Triglycerides
- Triglycerides are broken down to release fatty acids and glycerol for energy.
- Glycerol and fatty acids can be used in various metabolic pathways in different tissues.
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Description
Test your knowledge on the key aspects of fatty acid synthesis and its regulation. This quiz covers topics such as the rate limiting step, acetyl-CoA carboxylase activity, and the metabolic pathways involved. Perfect for students studying biochemistry or related subjects.
