Q How do steroid hormones enter a cell and bring about chang

Q. How do steroid hormones enter a cell and bring about change in expression of genes in the nucleus?

Solution

Steroid hormones are non-water soluble hormones. They are present in the blood bound to specific protein carriers.

When they have to enter a cell they dissociate from the protein carriers and enters the cell through simple diffusion.

Once entering the cell these hormones bind to hormone receptor proteins present in the cytoplasm and move as a hormone receptor complex into the nucleus where it encounters the DNA. Binding of hormone to receptor protein changes its conformational structure making it competent to bind DNA.

DNA inside the nucleus contains specific hormone response elements which recognises and binds to DNA binding regions of intracellular receptor protein.

The receptor protein also contains region which interacts with transcription factors thus initiating transcription at hormone response elements of DNA.

After transcription the mRNA moves to cytoplasm where specific proteins are synthesized through translation.