Chemical Coordination and Regulation Question 70
70. Identify $A, B$ and $C$ in the diagrammatic representation of the mechanism of hormone action. [2019, Odisha]
Physiological response
Select the correct option from the following :
(a) A=Protein hormone; B = Cyclic AMP;$C=$ Hormone-receptor complex
(b) $A=$ Steroid hormone; $B=$ Hormonereceptor complex;$C=$ Protein
(c) $A=$ Protein hormone; $B=$ Receptor $C=$ Cyclic AMP
(d) $A=$ Steroid hormone; $B=$ Receptor;$C=$ Second messenger
Show Answer
Answer : c
Hints & Solutions
(c) The given diagrammatic representation shows the mechanism of protein hormone action. ’ $A$ ’ is a hormone such as FSH that cannot cross lipid bilayer therefore it interacts with the membrane-bound receptors and does not enter the target cell, but generates second messengers. Peptide, polypeptide, protein hormones and catecholamines act through this mechanism. ‘B’ represents the extracellular receptors present on cell surface that forms a hormonereceptor complex which brings about conformational changes in the cytoplasmic part of the receptor. This cytoplasmic part can produces second messengers such as $Ca^{+2}$, cAMP, $IP_3$ etc. which activates the existing enzyme system of the cell and accelerates the biochemical reactions in the cell. Hence, ’ $C$ ’ represents the generation of second messenger.
