Human erythrocytes have no mitochondria. The rare inherited metabolic disorder that results from pyruvate kinase deficiency is particularly destructive to erythrocytes and causes hemolytic anemia
a) Suggest a reason for increased erythrocyte death in the presence of pyruvate kinase deficiency.
b) Suggest a reason for the low incidence of mutations in human glycolytic enzymes.
What will be an ideal response?
Answer: a) Erythrocytes make virtually all ATP through glycolysis. Pyruvate kinase catalyzes PEP phosphorylation of ADP to yield ATP and pyruvate, the last reaction in glycolysis. Without this reaction, glycolysis would net no ATP and the erythrocytes would die.
b) Glycolysis is such a fundamentally important pathway in all human cells that mutations in glycolytic enzymes are likely to be lethal in the embryo.
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On Monday morning, after you’ve already finished reading your email and begun assembling apparatus for your next series of tests, one of your colleagues arrives late, looking decidedly unwell. After exchanging the usual pleasantries, you find out the reason: There were two oranges in the fridge on Friday before it was your turn to clean it out. The other orange had fewer black mold spots than the one you triple-bagged while holding your breath…and your colleague really loves oranges. What was she suffering from over the weekend?
a. opportunistic mycosis b. mycetismus c. mycotoxicosis d. superficial mycosis
The plant tissue responsible for producing cells that thicken roots and stems is the
A. vascular bundle. B. intercalary meristem. C. apical meristem. D. lateral meristem. E. tracheid.
The three primary germ layers are formed during
a. fertilization. b. cleavage. c. organ formation. d. gastrulation.
The process by which a cell takes in a small amount of extracellular fluid by the ballooning inward of the plasma membrane is known as _______.
A. intracellular digestion B. exocytosis C. endocytosis D. extrusion E. osmosis