The video explains the G protein signaling pathway, focusing on the activation of adenylate cyclase by the G protein alpha subunit. It details the conversion of ATP to cyclic AMP and inorganic pyrophosphate, highlighting the role of inorganic pyrophosphatase in hydrolyzing pyrophosphate to drive cellular work. The video also discusses the exergonic nature of these reactions and their importance in cellular processes.

What is the initial step in G protein signaling?

• Hydrolysis of ATP

• Release of cyclic AMP

• Activation of adenylyl cyclase

• Binding of a neurotransmitter to a G protein-coupled receptor

What does adenylyl cyclase convert ATP into?

• GTP

• Protein kinase A

• Cyclic AMP and inorganic pyrophosphate

• Inorganic phosphate

Why is the reaction catalyzed by adenylyl cyclase considered exergonic?

• It forms a stable intermediate

• It decreases entropy

• It releases free energy

• It requires energy input

What role do magnesium ions play in the mechanism of adenylyl cyclase?

• They are not involved

• They act as a catalyst

• They stabilize the intermediate

• They are part of the substrate

What is formed during the mechanism of adenylyl cyclase?

• A linear intermediate

• A trigonal bipyramidal intermediate

• A tetrahedral intermediate

• A square planar intermediate

What is the role of cyclic AMP in the cell?

• It degrades proteins

• It activates protein kinase A

• It synthesizes ATP

• It inhibits protein kinase A

How does cyclic AMP affect protein kinase A?

• It binds to the catalytic subunit

• It degrades the catalytic subunit

• It inhibits the regulatory subunit

• It releases the regulatory subunit

What is the function of inorganic pyrophosphatase?

• It synthesizes ATP

• It hydrolyzes pyrophosphate into two phosphate molecules

• It converts cyclic AMP to ATP

• It activates protein kinase A

What is the result of the hydrolysis of inorganic pyrophosphate?

• Formation of ATP

• Release of free energy

• Synthesis of GTP

• Inhibition of protein kinase A

Why is the reaction catalyzed by inorganic pyrophosphatase important for the cell?

• It decreases cellular entropy

• It forms a stable compound

• It releases energy used for cellular work

• It consumes energy