Zapping Yeast with X-rays *
|Time Required||Long (2-4 weeks)|
|Prerequisites||Basic understanding of what radiation, DNA, and mutations are.|
|Material Availability||See How to Build an X-ray Machine for a detailed list of materials that will need to be ordered.|
|Cost||Very High (over $150)|
|Safety||See Introduction to Radiation & Radiation Safety for safety information.|
Have you ever wondered how X-rays affect living organisms? You have probably had X-rays taken at the dentist's or doctor's office. These X-rays are considered to be relatively safe, but every X-ray exposes a person to some radiation, specifically electromagnetic radiation. Radiation is energy that travels through space as either waves or high speed particles. Watch this video to learn more about electromagnetic radiation.
Watch this video which gives an introduction to light and electromagnetic radiation (Khan Academy).
When the energy in X-rays encounters an object, it can break chemical bonds. If this energy encounters a living organism, it can cause cellular damage, such as by directly damaging molecules like DNA, which contains the genetic instructions for an organism. This can cause mutations in the DNA.
How radiation affects something largely depends on the radiation dose. Being exposed to a relatively low dose of radiation over time is less hazardous than being exposed to a high dose at one time. This is because organisms can repair DNA damage over time and, given enough time between exposures to radiation, can usually repair it well. However, it is difficult for organisms to repair a large amount of damage that happens all at once. Depending on the amount, duration, and type of radiation exposure, high radiation doses can lead to radiation sickness, an increased risk of developing cancer, and/or death. However, doctors can also use radiation in radiation therapies to treat cancer, which is where cancer cells are specifically targeted with high doses of radiation that should only kill the cancer cells but leave the surrounding normal cells unharmed.
What radiation dose is needed to affect the growth of microorganisms? You can build your own X-ray machine to investigate how localized X-rays affect the growth of a common microorganism, baker's yeast. Read the Science Buddies Project Idea How to Build an X-ray Machine and the accompanying Introduction to Radiation & Radiation Safety to learn how you can safely make a homemade X-ray machine. There are several other Science Buddies Project Ideas that discuss how to grow yeast and use them to conduct investigations, such as Yeast Reproduction in Sugar Substitutes. What is the lowest radiation dose needed for you to see any difference in yeast growth? What is the lowest dose needed to completely kill the yeast, resulting in no growth? How do these radiation doses compare to what is considered safe for humans? How does it compare to the radiation dose a person receives from a single X-ray, or in an entire year on average?
Teisha Rowland, PhD, Science Buddies
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Last edit date: 2017-07-28
Here are a few websites that will help you start gathering information about radiation and X-rays:
- Khan Academy. (n.d.). Introduction to Light: Light and electromagnetic radiation. Retrieved January 27, 2012, from http://www.khanacademy.org/video/introduction-to-light?playlist=Cosmology+and+Astronomy
- National Aeronautics and Space Administration. (2011, March 22). X-rays. Retrieved January 25, 2012, from http://missionscience.nasa.gov/ems/11_xrays.html
- TeensHealth. (n.d.). Radiation Therapy. Retrieved January 25, 2012, from http://kidshealth.org/teen/cancer_center/treatment/radiation.html
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- If you are looking for something else to do with a homemade X-ray machine, try Developing Images with X-rays.
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