LABORATORY REVIEW
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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uracil
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cytosine
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guanine
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thymine
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Detailed explanation-1: -Answer and Explanation: An unmutated segment of DNA that contains 40 molecules of adenine, will contain an equal number of thymine as well. This is due to adenine always bonding with thymine in DNA.
Detailed explanation-2: -According to Chargaff’s rule, Concentration of adenine=concentration of thymine. therefore if [A]=40% then the [T] will also be 40%.
Detailed explanation-3: -Thymine (T) makes up 28% of the nucleotides in a sample of DNA from an organism.
Detailed explanation-4: -Chargaff’s rules explained that adenine always pairs with thymine and cytosine always pairs with guanine in a DNA molecule. Since adenine pairs with thymine, for every adenine base there will also be one thymine base. Thus, a sample with 15% adenine must also have 15% thymine.
Detailed explanation-5: -Therefore, Guanine would be 20% and total of G+C = 40% and hence A+T would be 60% that is 30% each. Hence, option C is correct answer.