Question 18 1 pts UV light can be used to sterilize surfaces (kill all microbes) and even be used to disinfect water (if the water is free of particles). UV light damages DNA by causing the formation of thymine dimers Pick the best answers (more than one) why UV light works as a physical method to sterilize surfaces or water. Side note: If you are a backpacker, you can purchase a UV sterilizer for your water bottle. We have used the UV sterilizer in addition to filtering our water when backpacking. Bacteria have enzymes which can repair DNA damage. However, if bacteria has extensive DNA damage, bacteria may not be able to keep up with DNA repair which can lead to cell death. Only human cells have the capability or mechanisms for repairing the damaged DNA. UV light DNA damage can inhibit DNA replication and transcription. Cells can't repair DNA damage so any DNA damage results in cell death.
Added by Montserrat L.
Close
Step 1
The question asks why UV light is a physical method for sterilization. The text explains that UV light damages DNA by forming thymine dimers. The answer choices describe different aspects of DNA repair and the effects of UV damage. Show more…
Show all steps
Your feedback will help us improve your experience
Adi S and 56 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Killing by Ultraviolet Light (UV Irradiation) Read the exercise in your lab manual and complete the exercises that follow. Ultraviolet (UV) light is often used as a physical method of control to prevent bacterial growth. UV light used to prevent or control the growth of bacteria must have a wavelength between 200 and 290 nm in order to be most effective. UV light within this range induces mutations in the DNA of the bacteria exposed. Thymine and/or cytosine nucleotides are rearranged by UV light, causing them to form dimers (thymine base pairing with other thymines or cytosine base pairing with another cytosine). This form of base pairing causes the DNA to become unreadable by replication or transcription machinery, rendering the DNA useless. An accumulation of these mutations quickly becomes lethal to the cell. UV irradiation is observed by inoculating plates with bacteria and immediately exposing the plates to UV light. Half of the plate may be covered with an index card in order to observe later the difference between exposure and non-exposure to UV radiation. Bacillus is used in order to show UV resistance in endospore-forming bacteria. Bacillus will be compared to Serratia, a non endospore-forming bacteria. Four plates will be prepared, one control (no UV exposure) and three different lengths of UV exposure. The plates are then incubated to prepare for observation at a later time. UV light is a part of sunlight and is a known cause of skin cancer. Human skin cells are constantly exposed to UV light from the sun and are susceptible to the same types of mutations as bacteria. Germicidal lamps are UV lamps in the 200-290 nm wavelength range used in restaurant kitchens, delicatessens and meat processing plants as a method to control and prevent food contamination by pathogens. Next time you go to the deli, look for the purple lamps!
Adi S.
UV radiation causes the formation of thymine dimers in a DNA strand, which prevents that strand from forming the bonds required for complementary base pairing, which means that the strand cannot undergo transcription or replication. Thinking about Lab 13: Control of Microbes by Ultraviolet (UV) Radiation, list 3 factors which might affect an organism's susceptibility to UV light: 1. Genetic factors 2. Environmental factors 3. Protective mechanisms
Sri K.
What part of the cell does UV damage affect most? a. cell membrane b. DNA c. proteins d. lipids e. sugars Should one protect the eyes and skin from exposure to UV? What are your predictions on the resistance of endospore forming bacteria to non-spore forming bacteria? Can't remember? Go to the cell chapter in your text; find endospores. Prions are infectious particles devoid of any nucleic acid, containing only protein. What is your prediction on the ability of prions to withstand UV sterilization? What are the wavelengths of UV-C light? How many US deaths per year are due to tanning beds? How is the University of Pennsylvania using UV light in their hospitals? What is the most significant pathogen in the group of bacteria that are beta hemolytic streptococci? What is (use your text book or notes) i. alpha hemolytic ii. beta hemolytic iii. gamma hemolytic?
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD