When cells are in the cuvette, the cells will scatter the light and the spectrophotometer will measure this scattering as in increase in absorbance. This scattering, or absorbance, increases as the cell concentration increases. Thus, the spectrophotometer can be a convenient tool to measure cell.
A 1940 study at the University of St. Andrews published in the 'BioChem Journal' definitively concluded that UV light exposure releases nitrogenous material from yeast cells.
![Spectrophotometer Spectrophotometer](http://faculty.bsc.edu/phanson/yen/growth_curve.jpg)
Most of this material is an amino-N substance, which, when released into the surrounding medium of the yeast cells, facilitates their growth and reproduction. This coincides with the results of a 1923 study published in the 'University of Chicago Press' that also demonstrated that UV light exposure increases yeast production. In that study, brewer's yeast exhibited a faster rate of fermentation. UV light, in large quantities over longer periods of time, does kill yeast cells eventually. A 1920 study published in the 'Botanical Gazette' noted that yeast does have a threshold after which it dies from overexposure to UV light. This threshold depends on the strength of the UV light source and the time of exposure. The study noted that as little as three minutes' exposure can kill yeast from high UV light strength, while the University of St.
Andrews study exposed the yeast to six hours of UV light, which killed 60 percent of the yeast cells. Thus, a balance between UV intensity and exposure time is necessary for the irradiation to yield desired results. Copyright ©2019Leaf Group Ltd.Use of this web site constitutes acceptance of the LIVESTRONG.COM,and.The material appearing on LIVESTRONG.COM is for educational use only. It should not beused as a substitute for professional medical advice,diagnosis or treatment. LIVESTRONG is a registered trademark of the LIVESTRONG Foundation.The LIVESTRONG Foundation and LIVESTRONG.COM do not endorseany of the products or services that are advertised on the web site.Moreover, we do not select every advertiser or advertisement that appears on the web site-many of theadvertisements are served by third party advertising companies.