Question

Compare and contrast how lipid soluble and amino-acid derived hormone signaling can control gene expression. At what level do they control gene expression? How do they control it? In your answer, be sure to explain: the flow of information from DNA to protein to describe how a gene is expressed and made into its protein product. Also the differences between receptors for amino acid-derived hormones and lipid soluble hormone

Answer 1

Peptide hormone signaling cascade:
Peptide hormones are hydrophilic molecules. So, they can not cross the lipid bilayer. They bind to the membrane receptors and activate them. Activated membrane receptors trigger downstream signaling events such as phosphorylation cascade or secondary messenger accumulation. This ultimately leads to the translocation/activation of a transcription factor. The activated transcription factor now binds to its downstream genes and mediates their activation/repression.

Steroid hormone signaling cascade:
Steroid hormones are derivative of cholesterol. They are hydrophobic in nature. So, they can easily pass through the cell membrane. they do not contain membrane receptors. Instead, they contain nuclear or cytosolic receptors. Binding of the ligand to the receptor activates it and the activated receptor mediates downstream events such as activation or repression of target genes.

Central dogma of life:

DNA ---> RNA ----> Protein.