Which of the following base is usually not present in DNA?
Correct Answer: Uracil
Description: Uracil is not usually present in DNA, instead thymine is present. However in DNA, spontaneous deamination of cytosine can produce uracil. But, this uracil is promptly recognized by Uracil DNA-glycosylase and replaced with cytosine. If uracil were present in DNA, DNA machinery could not differentiate the original uracil and the deaminated cytosine. Thus, presence of thymine/absence of uracil gives stability to DNA. Uracil is present in RNA in place of Thymine in DNA
Category:
Biochemistry
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