Final answer:
If a molecule of DNA contains 10% cytosine, it has 10% guanine due to Chargaff's rules, which state that the amount of cytosine is equal to the amount of guanine. Additionally, since adenine pairs with thymine, the molecule will have 40% adenine and 40% thymine respectively.
Step-by-step explanation:
If a molecule of DNA contains 10% cytosine, it also has 10% guanine because of the base pairing rules of DNA known as Chargaff's rules. These rules state that the amount of guanine is equal to the amount of cytosine (G=C) due to their complementary base pairing, where cytosine pairs with guanine through three hydrogen bonds.
Because DNA is comprised of pairs of nucleotides, the remaining percentage must add up to 100%. Since we know the amount of guanine and cytosine, we can deduce that adenine and thymine together make up the remaining 80%. Moreover, according to Chargaff's rules, adenine (A) pairs with thymine (T), meaning their percentages will also be equal in a DNA molecule. Therefore, the molecule has 40% adenine and 40% thymine.
So, if a DNA molecule has 10% cytosine, then it also has 10% guanine, 40% adenine, and 40% thymine respectively.