Question

Please help answer A, B, C and D.

T 3 Upis Due al the beginning of Class Friday, February - pusryruvate dehydrogenase deficiency causes neurodegenerative disorders. The symptoms Pyruvate dehydrogenase deficiency are chronic lactic acidosis, hypotonia, poor feeding, exercise erance, lethargy and abnormal brain development. This progressive disease leading to me retardation, blindness and spasticity. (A) Why would a deficiency of pyruvate dehydrogenase lead to elevated circulating lactate concentrations? (B) Why would a deficiency of pyruvate dehydrogenase lead to plasma acidosis? (C) Why would a deficiency of pyruvate dehydrogenase lead to exercise intolerance and lethargy? (D) Why would a deficiency of pyruvate dehydrogenase have such a drastic effect on the neurological tissue?

Answer 1

A. Pyruvate dehydrogenase converts pyruvate to acetyl CoA which enters in TCA cycle. If the enzyme is not present, pyruvate accumulates in the cytoplasm. Accumulating pyruvate will get converted in to lactic acid.

B. Acidosis is a due to the build up of the lactic acid. So huge amounts of lactic acid is synthesized in the body leading to acidosis. All the glucose is converting in to pyruvate. Pyruvate is getting accumulating. So accumulating pyruvate is converted in to lactic acid in the absence of pyruvate dehydrogenase.

C. Pyruvate has to get converted in to Acetyl Co-A to enter in to TCA cycle. In the TCA cycle, Acetyl Co-A will get completely burnt to release CO2, H2O and large amount of ATP. Conversion of pyruvate to Acetyl Co-A needs pyruvate dehydrogenase. In the absence of this enzyme, there is very less energy in the body. Such a person can't do any rigorous exercise.

D. Nerve tissue uses lot of energy at any point of time. Pyruvate dehydrogenase deficiency results in very low energy in the body. Because of lack of energy in the body nerve tissue gets affected. There will be reduced development of the nerve tissue in the body as the child is growing. So it will have great impact on the body.