This 13-minute video lesson provides a spectrophotometry Example: determining concentration based on absorbance. [Chemistry playlist: Lesson 101 of 106].
This 13-minute video lesson discusses spectrophotometry, transmittance, absorbance and the Beer-Lambert Law. [Chemistry playlist: Lesson 100 of 106].
In this laboratory students perform three exercises as an introduction to the basics of handling and analyzing DNA. In the first, they expose circular plasmid, linear phage, and high molecular weight genomic DNA samples to a variety of physical, thermal, chemical, and enzymatic conditions that might be expected to affect DNA integrity. The DNA's are analyzed by electrophoresis on a group agarose gel. In the second, they pour and reconstruct a "Frankengel" (a gel containing sections with three different agarose concentrations) on which they run a DNA ladder in order to investigate the effect of gel pore size on DNA fragment mobility. In the third, they perform an UV spectrophotometric analysis of DNA from which they learn to make purity and concentration estimates.
Laboratory Chemistry (5.310) introduces experimental chemistry for students requiring a chemistry laboratory who are not majoring in chemistry. Students must have completed general chemistry (5.111) and have completed or be concurrently enrolled in the first semester of organic chemistry (5.12). The course covers principles and applications of chemical laboratory techniques, including preparation and analysis of chemical materials, measurement of pH, gas and liquid chromatography, visible-ultraviolet spectrophotometry, infrared spectroscopy, kinetics, data analysis, and elementary synthesis.
This exercise enables students to gain insight into the process of excretion in insects. Rate of excretion and hemolymph volume in the migratory locust, Locusta migratoria, are measured using spectrophotometry. The capacity of two insects, the cockroach, Periplaneta americana, and L. migratoria, to detoxify ammonia via uricotelism is examined by measuring the concentration of uric acid in the insects' hemolymph and feces. Uric acid is quantified by ultraviolet spectrophotometry. The anatomy of the insect's excretory system is studied by dissection.
This exercise will allow students to actively learn about enzyme assays by performing two types that have relevance to the students interests, radial diffusion assay and spectrophotometry, and by using an enzyme, lysozyme, that is easily understandable and is applicable to their studies outside of this lab.
