Question

In the early 1900s, scientists thought that all organisms had an equal distribution of nucleotide bases. By 1950, Erwin Chargaff proved otherwise. He studied the DNA of several different organisms ( see table)and found that while their DNA shared the same four bases, A, C, G, and T, the proportions of the bases varied from one organism to another. He also found a relationship between the proportions of specific bases.

1.If you have a strand of DNA and 20% contains the base adenine how much thymine do you have? How much cytosine do you have? How much guanine do you have?
Thymine
Cytosine
Guanine

Answer 1

In a strand of DNA with 20% adenine, one would also find 20% thymine, according to Chargaff's rules.

Step-by-step explanation:

If we have a strand of DNA where 20% of the bases are adenine (A), then according to Chargaff's rules, the amount of thymine (T) would also be 20%. Chargaff's rules state that the amount of adenine is equal to the amount of thymine (A = T) and the amount of cytosine (C) is equal to the amount of guanine (G) (C = G). Since DNA is made up of these four bases and they must add up to 100%, if A and T together make up 40%, then C and G together must also make up the remaining 60%. Given that the amounts of C and G are equal, each would be half of 60%, which is 30%. Therefore, in the DNA strand, the amount of cytosine would be 30% and the amount of guanine would also be 30%.