Muscle Fibers Cannot Contribute Directly to Plasma Glucose Because They

Question

Muscle fibers cannot contribute directly to plasma glucose because they lack
A) Phosphorylase
B) Glucokinase
C) Glucose -1 -phosphatase
D) Phosphoglucomutase
E) Glucose-6-phosphatase

Accepted Answer

Muscle fibers cannot contribute directly to plasma glucose because they lack Glucose-6-phosphatase. This enzyme is necessary for the final step of gluconeogenesis and glycogenolysis, where it converts glucose-6-phosphate into glucose, which can then be released into the bloodstream. Muscle cells can store glucose as glycogen and use it internally but cannot export glucose to the blood due to the absence of this enzyme.