McqMate
| Q. |
Thiamidine dimer formation in DNA is caused by - |
| A. | IR-rays |
| B. | X-rays |
| C. | b and g-rays |
| D. | UV-rays |
| Answer» D. UV-rays | |
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Explanation: When cells are exposed to sunlight, radiant energy damage the DNA. For example, ultraviolet irradiation causes covalent bond formation between adjacent thymines on the same strand of DNA. Ultraviolet light is absorbed by a double bond in thymine and cytosine bases in DNA. This added energy opens up the bond and allows it to react with a neighboring base. |
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