Pentose Phosphate Pathway (PPP) Quiz

The Pentose Phosphate Pathway: Definition, Differences from EM Pathway, Reactions, Physiological and Clinical Significance

• The Pentose Phosphate Pathway (PPP) is an alternative pathway for glucose oxidation, also known as the hexose monophosphate shunt or pentose phosphate pathway.
• The PPP occurs in the cytosol of the cell and about 10% of glucose per day enters this pathway.
• The major purposes of the PPP are the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for use as a biochemical reductant, and the production of pentose phosphate for nucleotide synthesis.
• The PPP involves oxidative and non-oxidative reactions, with three molecules of glucose-6-phosphate entering the cycle and producing three molecules of CO2 and three molecules of 5 carbon residues, which give two molecules of glucose-6-phosphate and one molecule of glyceraldehyde-3-phosphate.
• The major differences between the Embden-Meyerhof (EM) pathway and the PPP include the fact that the EM pathway occurs in all tissues, while the PPP occurs in certain special tissues for a specific function.
• The PPP involves oxidation by dehydrogenation with NADP as the hydrogen acceptor, while the EM pathway involves oxidation by dehydrogenation with NAD as the hydrogen acceptor.
• ATP is required and produced in the EM pathway, while ATP is required but not produced in the PPP.
• CO2 is never formed in the EM pathway, while CO2 is produced in the PPP.
• The oxidative reactions of the PPP operate in organs such as the liver, lactating mammary glands, adipose, adrenal cortex, erythrocytes, testes and ovaries, and the lens of the eyes.
• The non-oxidative reactions of the PPP operate in all cell types synthesizing nucleotides and nucleic acids.
• The physiological significance of the PPP includes the generation of reducing equivalents for reductive biosynthesis of fatty acid, cholesterol, and steroids, free radical scavenging, erythrocyte membrane integrity, prevention of methemoglobinemia, preservation of the transparency of the lens of the eye, and macrophage bacteria activity.
• The clinical significance of the PPP includes glucose 6-phosphate dehydrogenase (G6PD) deficiency, which is the most common enzyme deficiency seen in clinical practice, and leads to hemolytic anemia characterized by anemia, jaundice, and black urine. G6PD deficiency occurs in all cells of the affected individual, but is most severe in erythrocytes, where the PPP provides the only means of generating NADPH. Precipitating factors for G6PD deficiency include treatment with oxidant drugs, ingesting fava beans (favism), and severe infection.

The Pentose Phosphate Pathway: Definition, Differences from EM Pathway, Reactions, Physiological and Clinical Significance

• The Pentose Phosphate Pathway (PPP) is an alternative pathway for glucose oxidation, also known as the hexose monophosphate shunt or pentose phosphate pathway.
• The PPP occurs in the cytosol of the cell and about 10% of glucose per day enters this pathway.
• The major purposes of the PPP are the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for use as a biochemical reductant, and the production of pentose phosphate for nucleotide synthesis.
• The PPP involves oxidative and non-oxidative reactions, with three molecules of glucose-6-phosphate entering the cycle and producing three molecules of CO2 and three molecules of 5 carbon residues, which give two molecules of glucose-6-phosphate and one molecule of glyceraldehyde-3-phosphate.
• The major differences between the Embden-Meyerhof (EM) pathway and the PPP include the fact that the EM pathway occurs in all tissues, while the PPP occurs in certain special tissues for a specific function.
• The PPP involves oxidation by dehydrogenation with NADP as the hydrogen acceptor, while the EM pathway involves oxidation by dehydrogenation with NAD as the hydrogen acceptor.
• ATP is required and produced in the EM pathway, while ATP is required but not produced in the PPP.
• CO2 is never formed in the EM pathway, while CO2 is produced in the PPP.
• The oxidative reactions of the PPP operate in organs such as the liver, lactating mammary glands, adipose, adrenal cortex, erythrocytes, testes and ovaries, and the lens of the eyes.
• The non-oxidative reactions of the PPP operate in all cell types synthesizing nucleotides and nucleic acids.
• The physiological significance of the PPP includes the generation of reducing equivalents for reductive biosynthesis of fatty acid, cholesterol, and steroids, free radical scavenging, erythrocyte membrane integrity, prevention of methemoglobinemia, preservation of the transparency of the lens of the eye, and macrophage bacteria activity.
• The clinical significance of the PPP includes glucose 6-phosphate dehydrogenase (G6PD) deficiency, which is the most common enzyme deficiency seen in clinical practice, and leads to hemolytic anemia characterized by anemia, jaundice, and black urine. G6PD deficiency occurs in all cells of the affected individual, but is most severe in erythrocytes, where the PPP provides the only means of generating NADPH. Precipitating factors for G6PD deficiency include treatment with oxidant drugs, ingesting fava beans (favism), and severe infection.

The Pentose Phosphate Pathway: Definition, Differences from EM Pathway, Reactions, Physiological and Clinical Significance

• The Pentose Phosphate Pathway (PPP) is an alternative pathway for glucose oxidation, also known as the hexose monophosphate shunt or pentose phosphate pathway.
• The PPP occurs in the cytosol of the cell and about 10% of glucose per day enters this pathway.
• The major purposes of the PPP are the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for use as a biochemical reductant, and the production of pentose phosphate for nucleotide synthesis.
• The PPP involves oxidative and non-oxidative reactions, with three molecules of glucose-6-phosphate entering the cycle and producing three molecules of CO2 and three molecules of 5 carbon residues, which give two molecules of glucose-6-phosphate and one molecule of glyceraldehyde-3-phosphate.
• The major differences between the Embden-Meyerhof (EM) pathway and the PPP include the fact that the EM pathway occurs in all tissues, while the PPP occurs in certain special tissues for a specific function.
• The PPP involves oxidation by dehydrogenation with NADP as the hydrogen acceptor, while the EM pathway involves oxidation by dehydrogenation with NAD as the hydrogen acceptor.
• ATP is required and produced in the EM pathway, while ATP is required but not produced in the PPP.
• CO2 is never formed in the EM pathway, while CO2 is produced in the PPP.
• The oxidative reactions of the PPP operate in organs such as the liver, lactating mammary glands, adipose, adrenal cortex, erythrocytes, testes and ovaries, and the lens of the eyes.
• The non-oxidative reactions of the PPP operate in all cell types synthesizing nucleotides and nucleic acids.
• The physiological significance of the PPP includes the generation of reducing equivalents for reductive biosynthesis of fatty acid, cholesterol, and steroids, free radical scavenging, erythrocyte membrane integrity, prevention of methemoglobinemia, preservation of the transparency of the lens of the eye, and macrophage bacteria activity.
• The clinical significance of the PPP includes glucose 6-phosphate dehydrogenase (G6PD) deficiency, which is the most common enzyme deficiency seen in clinical practice, and leads to hemolytic anemia characterized by anemia, jaundice, and black urine. G6PD deficiency occurs in all cells of the affected individual, but is most severe in erythrocytes, where the PPP provides the only means of generating NADPH. Precipitating factors for G6PD deficiency include treatment with oxidant drugs, ingesting fava beans (favism), and severe infection.

The Pentose Phosphate Pathway: Definition, Differences from EM Pathway, Reactions, Physiological and Clinical Significance

• The Pentose Phosphate Pathway (PPP) is an alternative pathway for glucose oxidation, also known as the hexose monophosphate shunt or pentose phosphate pathway.
• The PPP occurs in the cytosol of the cell and about 10% of glucose per day enters this pathway.
• The major purposes of the PPP are the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for use as a biochemical reductant, and the production of pentose phosphate for nucleotide synthesis.
• The PPP involves oxidative and non-oxidative reactions, with three molecules of glucose-6-phosphate entering the cycle and producing three molecules of CO2 and three molecules of 5 carbon residues, which give two molecules of glucose-6-phosphate and one molecule of glyceraldehyde-3-phosphate.
• The major differences between the Embden-Meyerhof (EM) pathway and the PPP include the fact that the EM pathway occurs in all tissues, while the PPP occurs in certain special tissues for a specific function.
• The PPP involves oxidation by dehydrogenation with NADP as the hydrogen acceptor, while the EM pathway involves oxidation by dehydrogenation with NAD as the hydrogen acceptor.
• ATP is required and produced in the EM pathway, while ATP is required but not produced in the PPP.
• CO2 is never formed in the EM pathway, while CO2 is produced in the PPP.
• The oxidative reactions of the PPP operate in organs such as the liver, lactating mammary glands, adipose, adrenal cortex, erythrocytes, testes and ovaries, and the lens of the eyes.
• The non-oxidative reactions of the PPP operate in all cell types synthesizing nucleotides and nucleic acids.
• The physiological significance of the PPP includes the generation of reducing equivalents for reductive biosynthesis of fatty acid, cholesterol, and steroids, free radical scavenging, erythrocyte membrane integrity, prevention of methemoglobinemia, preservation of the transparency of the lens of the eye, and macrophage bacteria activity.
• The clinical significance of the PPP includes glucose 6-phosphate dehydrogenase (G6PD) deficiency, which is the most common enzyme deficiency seen in clinical practice, and leads to hemolytic anemia characterized by anemia, jaundice, and black urine. G6PD deficiency occurs in all cells of the affected individual, but is most severe in erythrocytes, where the PPP provides the only means of generating NADPH. Precipitating factors for G6PD deficiency include treatment with oxidant drugs, ingesting fava beans (favism), and severe infection.