Final answer:
The effects of Gs and Gi on adenylyl cyclase in biology are that Gs stimulates adenylyl cyclase, leading to an increase in cAMP levels, while Gi inhibits adenylyl cyclase, decreasing cAMP levels.
Step-by-step explanation:
Adenylyl cyclase is an enzyme that catalyzes the conversion of ATP to cyclic adenosine monophosphate (cAMP). Gs proteins are associated with beta-adrenergic receptors and when activated by hormone binding, Gs proteins stimulate adenylyl cyclase, leading to an increase in cAMP levels. This increase in cAMP activates protein kinase A (PKA) which triggers a phosphorylation cascade, ultimately altering gene expression and mediating various cellular processes. On the other hand, Gi proteins, when activated, inhibit adenylyl cyclase, leading to a decrease in cAMP levels and subsequent inhibition of PKA activity.