Biology 2290F/G Final: Exam Notes.docx
12 Dec 2013
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Explain how the instrument works: tungsten lamp provides radiant energy of wavelength 340 to 900 nm, light is focused on a diffraction grating which splits the light into its component wavelengths. Describe transmittance and absorbance: transmittance = the fraction of incident light that passes through the sample, absorbance = amount of light absorbed by the sample. Convert transmittance values to absorbance values: a = log(1/t) Identify an appropriate blank to zero the spectrophotometer for a given experiment: everything contained in the experimental solution minus the compound of interest. Give examples of the principal uses of the spectrophotometer. (lab notes p. 13): absorption spectra, standard curve, rate of a biochemical reaction. Describe how to prepare absorption spectra and how they are used: absorbance values (y-axis) of a solution plotted against various wavelengths (x-axis) Describe how to prepare and use a standard curve of absorbance vs. concentration.
