This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Detection and Purification of Hormones”.
1. How are enzymes purified and detected?
a) Quantitative Bioassays
b) Enzyme assays
c) Arthrocentesis
d) Filtration
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Explanation: The scientists carry out the fractionation of extracts containing the putative hormone to extract a pure hormone. They use the same methods used to purify other biomolecules (solvent fractionation, chromatography, and electrophoresis), and then assays each fraction for testing the activity of hormones. It is possible to determine its composition and structure after the chemical has been purified.
2. Which hormone was first recognized as a substance produced from pancreas that affects the composition of urine?
a) Glucagon
b) Insulin
c) Vasopressin
d) Oxytocin
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Explanation: Insulin was first described as a compound formed in the pancreas that influences urinary volume and composition. A quantitative bioassay for the hormone may be established once a biochemical effect of the putative hormone is detected. In the case of insulin, the assay consisted of injecting pancreas extracts (a crude source of insulin) into insulin-deficient laboratory animals, then quantifying the resultant changes in blood and urinary glucose concentration.
3. Who characterized and purified thyrotropin-releasing hormone (TRH)?
a) Oskar Minkowski
b) Frederick G. Banting and Charles Best
c) Andrew Schally and Roger Guillemin
d) Josef Von Mering
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Explanation: Andrew Schally and Roger Guillemin independently purified and did the characterization of thyrotropin releasing hormone (TRH). It was extracted and characterized from the hypothalamus of the brain. They extracted this hypothalamus from animals including sheep and pigs.
4. Thyrotropin releasing hormone (TRH) is a derivative of which tripeptide?
a) Val-Leu-Gly
b) Pro-His-Gly
c) Glu-His-Arg
d) Glu-His-Pro
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Explanation: TRH has been recognized as a simple derivative of Glu-His-Pro. These are basically the amino acids, Glutamine, Histidine and Proline. When we understand the structure of a hormone, it is easy to chemically synthesize it in larger amounts for studies as well as clinical treatments.
5. In which year Schally and Guillemin shared the Nobel Prize in Physiology or Medicine for their work on hypothalamic hormones?
a) 1977
b) 1955
c) 1953
d) 1979
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Explanation: Schally and Guillemin shared the Nobel Prize in Physiology or Medicine in 1977 for their study on hypothalamic hormones with Rosalyn Yalow, who collaborated with Solomon A. Berson on another related work.
6. In 1977, Rosalyn Yalow won Nobel Prize for which work in endocrinology?
a) For the purification of insulin
b) Radioimmunoassay (RIA)
c) ELISA
d) Work on hypothalamic hormones
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Explanation: Rosalyn Yalow, in 1977 was awarded Nobel Prize for the development of the highly sensitive radioimmunoassay (RIA) for peptide hormones. This was used to study hormone action and functions. Through this technique, it was able to rapidly and quantitatively measure the hormones in very low concentration.
7. What is the modern equivalent of radioimmunoassay for hormonal studies?
a) Western blotting
b) In-situ hybridization
c) Enzyme linked immunosorbent assay (ELISA)
d) Double immune diffusion
View Answer
Explanation: ELISA is the modern equivalent of RIA. Hormone specific antibodies are the key to both of them. Hormones that are purified and injected into animals produce antibodies that bind to them in high affinity. These antibodies are purified and conjugated with an enzyme to produce a colored substrate in ELISA, whereas it is radio isotopically labeled in RIA.
8. While carrying our RIA (Radioimmunoassay) in animals, when we inject a purified hormone what is produced in their body?
a) Antigen
b) Peptides
c) Enzymes
d) Antibodies
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Explanation: The extracted hormone, injected into animals, produces antibodies of very high affinity and specificity that bind to the hormone. When a constant number of these isolated antibodies is incubated with a fixed amount of radioactively labelled hormones, a certain fraction of the radioactive hormone binds to the produced antibody.
9. What happens, if unlabeled hormone is also present in addition to the radiolabeled hormones in the quantitative measurement of Radioimmunoassay (RIA)?
a) Binding competition
b) Binding affinity
c) Transformation
d) Addition reaction
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Explanation: If the unlabeled hormone is also present in addition to the radiolabeled hormone, the unlabeled hormone competes with the antibody and displaces some of the labeled hormones from its binding site. By relation to a standard curve obtained with known quantities of unlabeled hormones, this binding rivalry can be quantified. A calculation of the amount of (unlabeled) hormone in the blood or tissue extract sample is the degree to which the labeled hormone is displaced from the antibody.
10. What characteristic of hormone is important in its quantitative assays of purification and determination?
a) Hormones have a low binding affinity
b) Hormones are extremely potent and are produced in very limited quantities.
c) Hormones are produced in larger quantities
d) Hormones are less reactive
View Answer
Explanation: Hormones are extremely potent and are produced in very limited quantities. The acquisition of sufficient hormones to enable its chemical characterization often requires biochemical isolation on a heroic scale. This hormone characterization protocol is deceptively simple.
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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