Which method of directly regulates PFK-I（）
A. allosteric activation by AMP
B. feedback inhibition by fructose 2,6-bisphosphate
C. allosteric activation by citrate
D. feed forward activation by phosphoenolpyruvate
查看答案
Which statement is TRUE of glycogen synthesis and breakdown（）
A. Phosphorylation activates the enzyme responsible for breakdown, and inactivates the synthetic enzyme
B. Synthesis is catalyzed by the same enzyme that catalyzes breakdown
C. The immediate product of glycogen breakdown is free glucose
D. Under normal circumstances, glycogen synthesis and glycogen breakdown occur simultaneously and at high rates
Covalent modification is one way the activity of specific enzymes can be regulated. Which enzyme is NOT regulated in this way（）
A. phosphofructokinase-2
B. pyruvate dehydrogenase
C. phosphorylase kinase
D. All of these enzymes are regulated by covalent modification
Which statement about mammalian glycogen synthase is NOT correct（）
A. It is especially predominant in liver and muscle
B. The donor molecule is a sugar nucleotide
C. The phosphorylated form of this enzyme is active
D. This enzyme adds the initial glucose unit to a tyrosine residue in glycogenin
Which statement is TRUE of glycogen synthase（）
Activation of the enzyme involves a phosphorylation
B. It catalyzes addition of glucose residues to the nonreducing end of a glycogen chain by formation of （α1 -4） bonds
C. It uses glucose-6-phosphate as donor of glucose units
D. The enzyme has measurable activity only in liver
微信支付 
支付宝支付