Describe hormone action at the genetic level (e.g., testosterone).

Testosterone is a hormone that acts at the genetic level by binding to specific receptors within the cell. Once testosterone binds to its receptor, the hormone-receptor complex is able to enter the cell nucleus and interact with specific regions of DNA. This interaction leads to the activation or repression of certain genes, ultimately influencing the expression of proteins that are involved in various physiological processes.

For example, in target cells such as muscle cells, testosterone binding to its receptor can activate genes that are involved in muscle growth and repair. This results in an increase in protein synthesis and muscle mass. On the other hand, in other tissues such as the prostate gland, testosterone binding to its receptor can activate genes that promote cell proliferation, which can contribute to the development of prostate cancer.

Overall, hormone action at the genetic level involves a complex series of interactions between hormones, their receptors, and specific genes, ultimately leading to changes in gene expression and cellular function.