Question

Erwin Chargaff's experiments on the composition of DNA provided clues about the structure of DNA. Select the statements that describe what Chargaff discovered about the base pair composition of DNA.

a) DNA molecules contain similar numbers of A and T bases and similar numbers of G and C bases.
b) The proportions of A:T base pairs and G:C base pairs are similar for members of the same species and vary between species.
c) Each DNA molecule contains approximately equal numbers of A, C, G, and T bases.
d) The proportions of A:G base pairs and C:T base pairs are the same for all species.

Answer 1

Erwin Chargaff discovered that the base pair composition of DNA follows specific rules - the amount of adenine always equals thymine, and the amount of guanine always equals cytosine. This discovery, known as Chargaff's rules, provided important insights into the structure of DNA.

Step-by-step explanation:

Erwin Chargaff's experiments on the composition of DNA provided important clues about the structure of DNA. He discovered that the amount of adenine (A) always equaled the amount of thymine (T), and the amount of guanine (G) always equaled the amount of cytosine (C) in DNA. This is known as Chargaff's rules. These rules showed that the base pairs in DNA are complementary, with A always pairing with T, and G always pairing with C.