Science Buddies: "Ask an Expert"

Hi! I started the yeast and UV radiation project and am having trouble with the counting the cultures part of it. Is there any way to tell whether the cells are dead or not? I asked my science teacher and he recommended using a microscope or something that could measure the carbon dioxide in the air, and I don't have the former and neither have nor understand how the latter would work. Do you have any recommendations on how to proceed with this?

Hi,

I hope you are having a great day! Thank you for your question.

For the "Exploring DNA Damage: What Effect Do Ultraviolet Rays Have on Yeast Colony Growth?" project, you should count the cultures by counting the number of colonies on the plates and then multiplying by the dilution factor (remember you have serially diluted these samples in a previous step). The colonies you see on the agar plates will be live cells only; in other words, dead cells (cells killed by UV damage) will not grow on the plates during the two day incubation period at room temperature. You could look at the yeast cells under the microscope to collect qualitative data and observe how the UV treatment affected the cells, but do note that this is not required for this project. The project focuses on collecting quantitative data as a measure of the effects of UV radiation on yeast cell growth.

Hope this helps! Please do not hesitate to reply on this forum if you have any further questions about the project. Good luck!

--Brandi