Exploring DNA Damage: What effect to ultraviolet rays have on yeast colony growth?
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Exploring DNA Damage: What effect to ultraviolet rays have on yeast colony growth?
We have started this experiment to test the effect of UV rays on yeast colony growth and have run into cloudy weather. We streaked the master plate 3 days ago. How long can we hold that master plate while waiting for sun, or what other options do we have?
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17eugenekim
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Re: Exploring DNA Damage: What effect to ultraviolet rays have on yeast colony growth?
Hello Kcold,
Thanks for coming to the Ask an Expert forums!
Ultimately the only issue with holding onto the master plate before UV exposure is that the yeast grows more. I think a few days should be alright, though I can't say for certain - a lot of it depends on what kind of yeast-growing conditions you're holding the plate in. Ultimately, the math shouldn't be affected because it's measuring the amount of yeast killed as a percentage of the amount of yeast visible in total.
If you are concerned, or would like to do it under more controllable conditions, you could instead do it indoors with a UV lamp. This does, however, add at least ~$20 to your project cost.
Hope that helps. Please don't hesitate to ask more questions!
Thanks for coming to the Ask an Expert forums!
Ultimately the only issue with holding onto the master plate before UV exposure is that the yeast grows more. I think a few days should be alright, though I can't say for certain - a lot of it depends on what kind of yeast-growing conditions you're holding the plate in. Ultimately, the math shouldn't be affected because it's measuring the amount of yeast killed as a percentage of the amount of yeast visible in total.
If you are concerned, or would like to do it under more controllable conditions, you could instead do it indoors with a UV lamp. This does, however, add at least ~$20 to your project cost.
Hope that helps. Please don't hesitate to ask more questions!
Re: Exploring DNA Damage: What effect to ultraviolet rays have on yeast colony growth?
Thank you for your advice. Can you suggest a specific UV lamp and also appropriate exposure times and how far away to put the lamp?
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17eugenekim
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- Joined: Sat Sep 01, 2018 4:14 pm
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- Project Status: Not applicable
Re: Exploring DNA Damage: What effect to ultraviolet rays have on yeast colony growth?
Sure! I can't really tell you what kind of lamp is best - as long as it has information like wavelength (UV light is generally defined as between 10nm and 400nm; a quick google search tells me that a lot of lamps use 365nm, but definitely check the product to be sure), you should be fine. If you're willing to go all-out, you could try and find a UV lamp designed specifically for lab purposes at a lab supplies store like Fisher Scientific. I'm not sure how much of a benefit there is in that, but you're welcome to try if you're willing.
Exposure time and lamp distance are hard to say decisively. In my experience disinfecting things with UV, exposure time is generally measured in minutes (so nothing past an hour, but also more than a few seconds). Distance probably depends a lot on the strength of the lamp - somewhere around a forearm's length is reasonable.
As a matter of fact, if you have time to make multiple plates, exposure time and lamp distance might be independent variables you might want to test out for a better experiment! Put the lamp at different times, or even at different angles to the plate, and set it for different periods of time - what happens at 5 minutes? 10? 20? What if you put the lamp closer?
Exposure time and lamp distance are hard to say decisively. In my experience disinfecting things with UV, exposure time is generally measured in minutes (so nothing past an hour, but also more than a few seconds). Distance probably depends a lot on the strength of the lamp - somewhere around a forearm's length is reasonable.
As a matter of fact, if you have time to make multiple plates, exposure time and lamp distance might be independent variables you might want to test out for a better experiment! Put the lamp at different times, or even at different angles to the plate, and set it for different periods of time - what happens at 5 minutes? 10? 20? What if you put the lamp closer?