42 Questions
Where is Acetyl-CoA synthetase present?
Cytoplasm and mitochondrial matrix
What is the role of CPT1 and carnitine in beta-oxidation?
To transport fatty acyl-CoA across the outer mitochondrial membrane
What happens to fatty acyl-CoA once it crosses the inner mitochondrial membrane?
It is regenerated via CPT2
What is the goal of beta-oxidation?
To produce energy in the form of NADH, FADH2, and acetyl-CoA
What happens when beta-oxidation is blocked by an inherited enzyme deficiency?
Excess fatty acids are diverted into TAG synthesis
What is the byproduct of beta-oxidation?
NADH, FADH2, and acetyl-CoA
What is the process of beta-oxidation?
The sequential cleaving of the fatty acyl group into acetyl-CoA units starting at the carboxyl end attached to CoA
Why is it called beta-oxidation?
Because the oxidation takes place at the beta carbon, followed by cleavage between the beta and alpha bond
What is the outcome of ω-oxidation of fatty acids?
Release of 1 propionyl CoA and 1 acetyl CoA
What is the site of synthesis of ketone bodies?
Mitochondrial matrix
What is the function of the enzyme cytochrome P450 in ω-oxidation?
To convert omega methyl to an alcohol
What is the role of NADPH in ω-oxidation?
To reduce cytochrome P450
What is the outcome of β-oxidation in the absence of carnitine?
Increased ω-oxidation
What is the product of ω-oxidation that undergoes β-oxidation?
Dicarboxylic acid
What is the enzyme that converts the alcohol to a carboxylic acid in ω-oxidation?
Dehydrogenase
In what cases is ω-oxidation increased?
In cases of carnitine deficiency
What is the byproduct of the first step in peroxisomal oxidation of VLCFAs?
Hydrogen peroxide
What is the purpose of catalase in peroxisomes?
To convert peroxide to water and oxygen
How does the first step of peroxisomal oxidation of VLCFAs differ from the first step of mitochondrial beta-oxidation?
Mitochondrial beta-oxidation uses oxidase
What is the purpose of the first step in peroxisomal oxidation of VLCFAs?
To activate VLCFAs
What is similar between the next 3 steps of peroxisomal oxidation of VLCFAs and mitochondrial beta-oxidation?
The enzymes used
What is the concern about the production of hydrogen peroxide in the first step of peroxisomal oxidation of VLCFAs?
It can generate toxic free radicals
How does peroxisomal oxidation of VLCFAs differ from beta-oxidation in terms of energy production?
Peroxisomal oxidation is not linked to energy production
What is the difference between the genes that encode the enzymes in peroxisomal oxidation of VLCFAs and mitochondrial beta-oxidation?
The genes are different
What is the role of Succinyl CoA in short-term control of ketone body synthesis?
It allosterically inhibits HMG CoA synthase
What is the effect of glucagon on ketone body synthesis in the short-term?
It decreases succinyl CoA
What is the effect of starvation on HMG CoA synthase and mRNA expression?
It increases HMG CoA synthase and mRNA expression
Which of the following tissues cannot use ketone bodies as fuel?
Liver
What is the primary function of HMG synthase in ketone body synthesis?
To convert acetoacetyl CoA to HMG CoA
What is the fate of acetoacetate in ketone body synthesis?
It is transferred or entered into the blood directly
What is the enzyme involved in the reversible reaction of beta-oxidation?
Thiolase
What is the role of HMG lyase in ketone body synthesis?
It converts HMG CoA to acetoacetate
Which of the following fatty acids still requires β-oxidation for energy production in a child with an enzyme deficiency?
Octanoic acid
What is the consequence of a deficiency in ETF:CoQ oxidoreductase?
Electrons cannot be transferred from FAD(2H) to coenzyme Q
What is the outcome of a lack of α-oxidation in phytanic acid metabolism?
β-oxidation is blocked
Which enzyme is required for the transfer of electrons from FAD(2H) to coenzyme Q?
ETF:CoQ oxidoreductase
What is the result of hypoketotic hypoglycemia in a child with an enzyme deficiency?
Death may result
What is the role of α-oxidation in phytanic acid metabolism?
To break down methyl branches
Why is octanoic acid a useful energy source in a child with an enzyme deficiency?
It can bypass the defective enzyme
What is the effect of a deficiency in ETF:CoQ oxidoreductase on gluconeogenesis?
It is shut down
Which of the following fatty acids requires a special oxidation step before β-oxidation?
Phytanic acid
What is the consequence of an enzyme deficiency in a child during times of fasting?
No energy will be forthcoming
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