Refer to the figure below to answer the questions Quiz 3 (15 pts v4.Cen e-C 1 00
ID: 281593 • Letter: R
Question
Refer to the figure below to answer the questions Quiz 3 (15 pts v4.Cen e-C 1 00 75 5? . 2 25 11 10 9 7-6-5 Log [Agonist] (molar) 1. What is the Bmax of Hormone A? 2. 3. 4. What is the Bmax of Hormone B? What is the Bmax of Hormone C?? If Hormone A is a full agonist, then what does that make Hormone B? Ko7 ? Kp? Ko? (1 ) ?????? And what does that make Hormone C? Why? 5. 6. 7. Of the 3 hormones, which is the most potent? On the figure, draw the binding curve of an antagonist. Label this On the figure, draw the binding curve that would result if "A" w 3) antagonist. Label this curve "Y".Explanation / Answer
Answer 1.
KD is half of the Bmax. Therefore in question 1, Bmax of hormone A is 100 and KD is -9 [pKD (-log10 KD) of 9].
Answer 2.
KD is half of the Bmax. Therefore in question 2, Bmax of hormone B is 100 and KD is -7 [pKD (-log10 KD) of 7].
Answer 3.
KD is half of the Bmax. Therefore in question 1, Bmax of hormone C is 50 and KD is -9 [pKD (-log10 KD) of 9].
Answer 4.
If A is a full agonist then hormone B will be a competitive antagonist. As evident from the graph, the efficacy of hormone B is similar to that of hormone A. However, hormone A is more potent than B as a maximum effect is achieved at a lower dose. Hormone B is a competitive antagonist because it is reaching maximum response after the increase in concentration, which is a characteristic of competitive inhibition. This is because receptor binding is a saturable and reversible process. When the competitive antagonist is present we have to increase the concentration of ligand so that it displaces inhibitor and the full response is achieved.
Hormone C is a non-competitive antagonist. Since in this case there is no effect on maximum response despite increasing the concentration, this is a characteristic of non-competitive inhibition. This is generally seen when the receptor is blocked irreversibly and therefore increase in concentration cannot reverse the receptor inhibition and response do not increase with an increase in concentration.