Question

Place in correct order the action of a water-soluble hormone on its target cell.

1. Adenlyte cyclase is activated, catalyzing the conversion of ATP to cAMP.
2. Enzymes catalyze reactions that produce a physiological response attributes to the hormone.
3. The hormone binds to a membrane receptor.
4. Activated protein kinases phosphorylate cellular proteins.
5. The hormone-receptor complex activates G proteins.
6. Cyclic AMP activates protein kinases.

Answer 1

The correct sequence starts with the hormone binding to a receptor, followed by the activation of G proteins, conversion of ATP to cAMP, activation of protein kinases, phosphorylation of proteins, and culminates in the physiological response.

Step-by-step explanation:

The correct order of action for a water-soluble hormone on its target cell is as follows:

1. The hormone binds to a membrane receptor.
2. The hormone-receptor complex activates G proteins.
3. Adenylyl cyclase is activated, catalyzing the conversion of ATP to cAMP.
4. Cyclic AMP (cAMP) activates protein kinases.
5. Activated protein kinases phosphorylate cellular proteins.
6. Enzymes catalyze reactions that produce a physiological response attributed to the hormone.

Water-soluble hormones initiate a signaling cascade that is greatly amplified at each step, ensuring that a small concentration of hormone can have a significant effect on the target cell. To prevent over-activation, cAMP is broken down by phosphodiesterase (PDE), which helps to regulate the hormone activity.