This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Hormone Binding and Regulation of Hormone Sensitivity”.
1. What phenomenon can give an explanation for several pathologic conditions, such as hypoglycemia caused by tumors secreting IGF2 and hyperthyroidism associated with choriocarcinoma?
a) Specificity spillover
b) Rational spillover
c) Lowering affinity
d) Raising affinity
View Answer
Explanation: Specificity spillover is the phenomenon that gives explanation for many physiological conditions. This includes hypoglycemia caused by tumors secreting IGF2 and hyperthyroidism associated with choriocarcinoma.
2. What is the name of the plot which is used to estimate the affinity with which a receptor binds its hormone?
a) Senicate plot
b) Scatchard plot
c) Westrick plot
d) Handard plot
View Answer
Explanation: As a graphic approach to estimate the affinity with which a receptor binds the hormone, a plot, referred to as a Scatchard plot, has been used. And if these basic equations more or less precisely explain the binding properties of certain receptors, other receptors exhibit more complicated properties.
3. Which among the following receptors have more than one binding site?
a) Thyroid Receptor
b) Adrenaline Receptor
c) Insulin Receptor
d) Activin Receptor
View Answer
Explanation: Few receptors have more than one binding site, such as the insulin receptor. And the binding sites may have mutual interactions. The insulin receptor plays a key role metabolically in the control of glucose homeostasis, a functional mechanism that can lead to a number of clinical manifestations, including diabetes and cancer, under degenerate conditions.
4. A straight line is obtained when (HR)/(H), that is the ratio of bound to free hormone, is plotted as a function of (HR), which is the concentration of bound hormone.
a) True
b) False
View Answer
Explanation: When (HR)/(H) (i.e., the bound to free hormone ratio) is plotted as a function of (HR), a straight line is obtained (the concentration of bound hormone). The line slope is -Ka, and at the point where (HR)=R0=the complete number of binding sites, the line intercepts the horizontal axis.
5. The Scatchard equation implies that only one type of receptors is present.
a) True
b) False
View Answer
Explanation: The Scatchard equation indirectly suggests that only one class of receptors exists and that the receptor binding sites do not interfere with each other. The Scatchard plot may not be linear if these assumptions do not extend to the relationship of a specific hormone with its receptor.
6. Which receptor relies on the binding of guanosine diphosphate (GDP) or guanosine triphosphate (GTP)?
a) Insulin Receptor
b) G protein coupled receptor
c) Thyroid Receptor
d) Activin Receptor
View Answer
Explanation: The association between a G protein and a GPCR can impact the affinity with which its ligand is bound by the receptor. The influence on binding affinity depends on whether the G protein is bound to guanosine diphosphate (GDP) or guanosine triphosphate (GTP).
7. Hormone sensitivity is directly related to what factor of the hormone receptor?
a) Number of hormone receptors
b) Binding affinity of hormone receptors
c) Type of the hormone receptors
d) Specificity of the hormone receptors
View Answer
Explanation: Hormone response is closely related to the number of hormone receptors expressed on the cell surface when all other factors are similar. The affinity of hormone binding or coupling performance to downstream signaling pathways can be changed by posttranslational receptor modifications.
8. What reaction can affect downstream components in the hormone action pathway?
a) Anabolic influences
b) Catabolic influences
c) Genetic influences
d) Regulatory influences
View Answer
Explanation: In the hormone action pathway, all of the downstream elements are subject to related forms of regulatory influences. This may have a direct effect on the hormone-responsive potential of the target cell.
9. What reaction can cause disease by targeting components of the hormone action pathway?
a) Pathological influences
b) Regulatory influences
c) Genetic influences
d) Catabolic influences
View Answer
Explanation: Just as hormone sensitivity is subject to normal physiological control, pathological influences may induce diseases. The hormone activity pathway can be compromised by several etiological influences.
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