30 Questions
What is the normal concentration of ketone bodies in the circulation?
1mM
What is required for the synthesis of ketone bodies?
Fatty acids available for oxidation in the liver
What is the role of ketone bodies in the body?
They are used by all tissues containing mitochondria
What is the primary component of cell membrane?
Cholesterol
What is the consequence of a fall in plasma insulin?
It activates the lyase and inhibits the reductase
Where does lipolysis occur in the process of ketone body synthesis?
In adipose tissue
What is the primary function of the enzymes found in the liver and kidney?
To remove the NH2-group from amino acids
What is the usual keto-acid involved in the transamination reaction?
α-ketoglutarate
What is the product of the reaction between glutamic acid and pyruvic acid?
Alanine and α-keto glutarate
What is the product of the reaction between glutamine and glutaminase?
Glutamate and NH3
What is the purpose of detoxifying ammonia in the body?
To prevent the build-up of toxic compounds
What is the clinical significance of transaminases in the blood?
To assess liver function
Why is early diagnosis of PKU crucial?
To prevent irreversible damage
What is the composition of creatine kinase?
Two subunits of different types (B and M)
What is the byproduct of the deamination reaction?
NH3
What is the normal blood concentration of ammonia?
Low, around 25-40μM
What is the consequence of a complete loss of an enzyme in the urea cycle?
Fatal
Which of the following is NOT a transaminase of clinical importance?
Glutamate transaminase (GT)
What is the primary purpose of a low-protein diet in the treatment of urea cycle defects?
To restrict the amount of amino acid in the diet
What is the source of ammonia produced during amino acid degradation?
Gut bacteria
What is the enzyme involved in the transamination reaction?
Transaminase
What is the molecular basis of the toxic effect of ammonia?
Its reaction with alpha-ketoglutarate to form glutamate
What is the purpose of replacing amino acids with keto acids in the treatment of urea cycle defects?
To restrict the amount of amino acid in the diet
How is PKU typically diagnosed in newborns in the UK?
Through screening for phenylketones in urine and phenylalanine in blood
Which of the following amino acids is essential and cannot be totally removed from the diet?
Phenylalanine
What is the reaction catalyzed by creatine kinase in muscle cells?
Creatine + ATP → Creatine Phosphate + ADP
What is the consequence of elevated levels of homocysteine and methionine in plasma and the presence of homocystine in the urine?
Homocystinuria
What is the significance of the amount of creatinine in blood and urine?
Indicates kidney function and muscle turnover
What is the toxic compound that accumulates in phenylketonuria?
Phenyl pyrovic acid
What is the significance of the three different enzymes of creatine kinase?
They are isoenzymes with different tissue distributions
Understand how lipids are transported in the bloodstream, how tissues obtain lipids from lipoprotein, and clinical problems associated with lipid transport. This session covers lipid metabolism and transport, including ketone bodies.
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