Many of the mechanisms involved in the regulation of glycogen metabolism involve covalent modification of enzymes. In particular, reversible phosphorylation/dephosphorylation plays a central role. 

(a) Estimate the ∆G°′ for the dephosphorylation of phosphorylated Ser-14 of glycogen phosphorylase (catalyzed by phosphoprotein phosphatase 1). Explain your reasoning. 

(b) Estimate the ∆G°′ for the phosphorylation of Ser-14 of glycogen phosphorylase by ATP (catalyzed by phosphorylase kinase). Explain your reasoning. 

(c) Would you expect both reactions to be favorable under physiological conditions (i.e., to possess a negative ∆G)?