Use of a laboratory exercise on molar absorptivity to help students understand the authority of the primary literature.
Biochem Mol Biol Educ
; 36(1): 61-4, 2008 Jan.
Article
em En
| MEDLINE
| ID: mdl-21591161
ABSTRACT
To promote understanding of the authority of the primary literature in students taking our biochemistry laboratory courses, a biochemistry laboratory exercise on the determination of an acceptable molar absorptivity value of 2-nitrophenol (2-NP) was developed. This made the laboratory course much more relevant by linking to a thematic thread, ß-galactosidase, that scaffolds concepts in one exercise with those in later exercises. The substrate for the continuous assay of ß-galactosidase is the chromogenic 2-nitrophenyl-ß-D-galactopyranoside that produces 2-NP. In an early laboratory exercise, students determine the wavelength of maximum absorption for the protonated and deprotonated form of 2-NP at various pH values and then determine the molar absorptivity of 2-NP. Students were encouraged to discuss apparent discrepancies not only in their own determinations of molar absorptivity values for 2-NP, but also in the published molar absorptivity values for 2-NP (2,150-21,300 M(-1) cm(-1) ) at almost the same pH and at 420 nm. Finally, the students were led to a publication that serves as an authentic source for molar absorptivity of 2-NP.
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MEDLINE
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En
Ano de publicação:
2008
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Article