Answer:
Amino acid-based hormones use a second messenger, cyclic AMP, but steroid hormones __________complex inside the nucleus with a receptor and DNA to initiate protein synthesis______________.
Step-by-step explanation:
Steroid hormones (among them: estrogen, progesterone, estradiol, cortisol, aldosterone) cross the plasma membrane joining intracellular receptors. These hormone-receptor complexes bind to specific DNA sequences, called hormonal response elements HRE), leading to modifications in gene transcription.