50 Questions
What is the primary substrate for lipogenesis in most mammals?
Glucose
Which molecule is the main fuel molecule produced by the diet in ruminants for lipogenesis?
Acetate
What critical diseases of the fatty acid biosynthesis pathway have not been reported in humans?
Insulin resistance
What is the benefit of having a high ratio of polyunsaturated fatty acids to saturated fatty acids (P:S ratio) in the diet?
Preventing coronary heart disease
Which essential fatty acids are used to form eicosanoic (C20) fatty acids that give rise to prostaglandins, thromboxanes, leukotrienes, and lipoxins?
Polyunsaturated fatty acids derived from plants
What functions do prostaglandins mediate according to the text?
Inflammation, pain, and regulating blood coagulation
What is the enzyme activity responsible for liberating the Fatty Acid Synthase complex from a free palmitate molecule?
Thioesterase
Which molecule must the free palmitate be converted to before proceeding through any other metabolic pathway?
Acyl-CoA
Which process describes the usual fate of palmitate after it is liberated from the Fatty Acid Synthase complex?
Esterification into acylglycerols
In which gland is there a specific thioesterase for acyl residues of 𝐶8, 𝐶10, or 𝐶12, found in milk lipids?
Mammary gland
Which molecule acts as a primer for the synthesis of long-chain fatty acids with an odd number of carbon atoms?
Propionyl CoA
What is the main source of NADPH for lipogenesis?
Pentose Phosphate Pathway
Which molecules act as cofactors in the biosynthesis of fatty acids?
NADPH, ATP, Mn2+, biotin, and HCO3-
What is the immediate substrate in the biosynthesis of fatty acids?
Acetyl-CoA
Which vitamin is required by acetyl-CoA carboxylase in fatty acid synthesis?
Biotin
What is the main pathway for de novo synthesis of fatty acids?
Lipogenesis
Which substance is required in the initial reaction for the carboxylation of acetyl-CoA to malonyl-CoA?
Bicarbonate (HCO3-)
What type of properties do leukotrienes have?
Muscle contractant and chemotactic properties
What is the initial and controlling step in fatty acid synthesis?
Formation of malonyl-CoA
How does the synthase system differ in bacteria and plants compared to yeast, mammals, and birds?
Yeast, mammals, and birds have a multienzyme complex while bacteria and plants have separate enzymes.
What role does 4'-phosphopantetheine play in the fatty acid synthase complex?
Component of ACP in yeast, mammals, and birds
What is a key advantage of using a multienzyme functional unit for fatty acid synthesis?
Achieving compartmentalization without erecting permeability barriers
In mammals, how many monomers make up the fatty acid synthase complex?
Two monomers with all seven enzyme activities each
Which type of organism uses acyl carrier protein (ACP) in the fatty acid synthase system?
Yeast
Which metabolic pathway is the chief source of hydrogen required for the reductive synthesis of fatty acids?
Pentose phosphate pathway
Which tissues possess an active pentose phosphate pathway and are specialized in active lipogenesis?
Adipose tissue
What is the main source of NADPH required for lipogenesis?
Malate to pyruvate conversion
Where is acetyl-CoA mainly formed from glucose for fatty acid synthesis?
Mitochondria
Which reaction converts malate to pyruvate and is involved in generating NADPH for lipogenesis?
Malic enzyme reaction
Why does acetyl-CoA not diffuse readily into the extramitochondrial cytosol?
Principal site of fatty acid synthesis is outside mitochondria
What is the fate of citrate in the extramitochondrial compartment?
It is converted to acetyl-CoA and oxaloacetate
What enzyme catalyzes the cleavage of citrate into acetyl-CoA and oxaloacetate?
ATP-citratlyase
How is NADPH generated from oxaloacetate via malate?
By malate dehydrogenase
What is the function of the malic enzyme in the context of lipogenesis?
Generating NADPH from malic acid
How can reducing equivalents be transferred from extramitochondrial NADH to NADP?
Via malate formation from citrate
In what form does malate need to be for the citrate transporter to exchange it with citrate in the mitochondrion?
Oxaloacetate
What is the primary role of acetyl-CoA in fatty acid biosynthesis?
Formation of malonyl-CoA
How is pyruvate used in the context of fatty acid synthesis?
To regenerate acetyl-CoA in the mitochondrion
Which molecule is required for the exchange of citrate with malate in the mitochondrion?
Oxaloacetate
What is the significance of ATP in the cleavage of citrate into acetyl-CoA and oxaloacetate?
Provides energy for the reaction
What is the fate of citrate after it is translocated into the extramitochondrial compartment?
It is converted back to acetyl-CoA by ATP-citratlyase
Which enzyme catalyzes the cleavage of citrate into acetyl-CoA and oxaloacetate?
ATP-citratlyase
What is the primary building block used in the biosynthesis of fatty acids?
Acetyl-CoA
Which molecule is responsible for transferring reducing equivalents from extramitochondrial NADH to NADP?
Malate
What is the final product generated by malic enzyme from oxaloacetate?
NADPH
Which enzyme converts malate to pyruvate for generating NADPH in lipogenesis?
Malic enzyme
Where does the tricarboxylate transporter translocate citrate into?
Extramitochondrial compartment
In which state does ATP-citratlyase exhibit increased activity?
'Well-fed' state
What is the role of pyruvate in relation to acetyl-CoA in lipogenesis?
Transports acetyl-CoA into mitochondria for synthesis
What is the function of the malic enzyme in lipogenesis?
Generates NADPH from oxaloacetate.
Test your knowledge on the biosynthesis of fatty acids focusing on the production of malonyl-CoA, which is the initial and controlling step in fatty acid synthesis. Learn about the role of acetyl-CoA carboxylase and the fatty acid synthase complex in this process.
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