Different Ways Steroids And Protein Hormones Interact With Target Cells

Question 1

How do steroid (lipid soluble) hormones interact with their target cells?

Answer 1

They diffuse into the cell and bind to an intracellular hormone receptor to activate mRNA transcription in the nucleus as the complex binds to receptors on chromatin to make the cell create more Na channels. (Change cell activity by changing enzyme activity)

Question 2

How do peptide(insulin) protein hormones/amino acid derivatives (adrenaline) interact with their target cells?

Answer 2

They interact with surface hormone receptors on the plasma membrane as 1st messenger. The complex activates adenylyl cyclase so
ATP->cAMP = 2nd messenger, activates protein kinase enzymes which alter cell functions by catalysing a wide array of actions (regulating enzymes, synthesising proteins, secreting molecules). 2nd messenger amplifies effect on cell.