If a double stranded DNA has 20% of cytosines, calculate the percent o...
In a DNA molecule, the number of cytosine molecules is equal to guanine molecules and the number of adenine molecules are equal to Thymine molecules. Thus, If a double stranded DNA has 20% of cytosine, it has 20% of guanine. Thus, cytosine plus guanine make 40% of the total bases. The remaining 60% includes both adenine and thymine which are in equal amounts. Therefore, the percent of adenine is 30%.
If a double stranded DNA has 20% of cytosines, calculate the percent o...
To calculate the percent of adenine in a double-stranded DNA, we need to understand the base pairing rules of DNA. In DNA, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). Therefore, the percentage of adenine in a DNA molecule is equal to the percentage of thymine.
Given that the DNA has 20% cytosines, we can assume that the percentage of guanines is also 20%. This is because the percentage of cytosines is equal to the percentage of guanines due to base pairing rules.
Since adenine pairs with thymine, and the percentage of thymine is equal to the percentage of cytosines (20%), the percentage of adenine in the DNA would also be 20%.
However, this answer is not among the options provided. So, let's evaluate the other options:
a) 20%: This is a possibility, as explained above.
b) 40%: This is not possible because the percentage of adenine can never be more than the percentage of cytosine or guanine.
c) 30%: This is the correct answer. It is not equal to the percentage of cytosine but rather the sum of the percentages of adenine and thymine (since they always pair together).
d) 60%: This is not possible because the percentage of adenine can never be more than 50% in a DNA molecule.
Therefore, the correct answer is option c) 30%, as it represents the sum of the percentages of adenine and thymine in the DNA molecule.