Question

The following questions will require you to compare and contrast cell surface receptors and steroid hormone receptors.

(a) Which type of receptor is more likely to have a hydrophobic ligand?

(b) which type of receptor results in changes in gene transcription? Explain.

(c) do peptide ligands usually travel to the nucleus with their receptors?

(d) what is the benefit of a multistep signalling pathway over a single step signalling pathway?

Answer 1

A. Hydrophobic/Lipophilic ligand can easily cross the cell membrane as they are soluble in the lipid bilayer and can bind to their respective receptors present inside the cell.

B. Nuclear/Cytoplasmic receptors which binds to ligand inside the cell can result in changes in gene transcription.

C. No, they activate a series of intracellular receptors through their cell surface receptor known as signalling cascade in which second messenger system is activated.

D. A signaling cascade or signaling pathway, is a series of chemical reactions which are initiated by ligand (first messenger) acting on the cell surface receptor which is transduced to the inside of the cell through second messengers (which multiplies the initial signal) and ultimately to effector molecules, resulting in a cell response to the first messenger. At each step of the signaling pathway, various regulating factors are involved to regulate cellular actions, responding effectively to clues about their changing environment inside and outside the cell.