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Question
Which of the following is not an intermediate of Krebs cycle?
Which of the following is not an intermediate of Krebs cycle?
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Solution
The correct option is D PGAL
Krebs cycle is a series of chemical reactions that occurs inside the mitochondria of aerobic organisms that aims at releasing the stored energy of organic food substances through the stepwise oxidation of acetyl CoA obtained from pyruvate during glycolysis.
Krebs’ cycle starts with condensation of acetyl group (acetyl CoA) with oxaloacetate (4- carbon compound) in the presence of a condensing enzyme citrate synthase to form a tricarboxylic, 6- carbon compound called citric acid. It is the 1st product of Krebs cycle. CoA is liberated.
In the 3rd step of Krebs cycle there is formation of 𝝰-ketoglutarate.
Isocitrate undergoes oxidative decarboxylation in the presence of enzyme isocitrate dehydrogenase and Mn2+. A transient oxalosuccinate is formed as intermediate. It undergoes decarboxylation to form a 5- carbon 𝝰-ketoglutarate also known as 2-oxoglutarate. NADH (reduced nicotinamide adenine dinucleotide) is produced in this step.
In the 7th step of Krebs cycle, fumarate is hydrated in the presence of enzyme fumarase to form malate.
OAA, 𝝰.-ketoglutarate and Malate are all intermediates of Krebs cycle. PGAL is an intermediate of glycolysis.
Krebs cycle is a series of chemical reactions that occurs inside the mitochondria of aerobic organisms that aims at releasing the stored energy of organic food substances through the stepwise oxidation of acetyl CoA obtained from pyruvate during glycolysis.
Krebs’ cycle starts with condensation of acetyl group (acetyl CoA) with oxaloacetate (4- carbon compound) in the presence of a condensing enzyme citrate synthase to form a tricarboxylic, 6- carbon compound called citric acid. It is the 1st product of Krebs cycle. CoA is liberated.
In the 3rd step of Krebs cycle there is formation of 𝝰-ketoglutarate.
Isocitrate undergoes oxidative decarboxylation in the presence of enzyme isocitrate dehydrogenase and Mn2+. A transient oxalosuccinate is formed as intermediate. It undergoes decarboxylation to form a 5- carbon 𝝰-ketoglutarate also known as 2-oxoglutarate. NADH (reduced nicotinamide adenine dinucleotide) is produced in this step.
In the 7th step of Krebs cycle, fumarate is hydrated in the presence of enzyme fumarase to form malate.
OAA, 𝝰.-ketoglutarate and Malate are all intermediates of Krebs cycle. PGAL is an intermediate of glycolysis.