To solve the problem, we need to determine the number of Guanine and Adenine bases present in the DNA molecule at a pitch of 170° with 130 hydrogen bonds between base pairs.
1. Understanding the Base Pairing in DNA: In DNA, base pairing follows the rule of complementary base pairing: Guanine (G) pairs with Cytosine (C), and Adenine (A) pairs with Thymine (T). The number of hydrogen bonds between base pairs is as follows:
G-C pairs have 3 hydrogen bonds.
A-T pairs have 2 hydrogen bonds.
2. Analyzing the Pitch and Base Pair Relationship: The pitch of the DNA molecule (the distance for one full turn of the helix) is 170°. Since each base pair contributes a certain number of hydrogen bonds, we need to match the number of hydrogen bonds to the options provided.
3. Determining the Correct Combination: Given that there are 130 hydrogen bonds between the base pairs, and we know that G-C pairs contribute 3 hydrogen bonds and A-T pairs contribute 2 hydrogen bonds, we can set up the equation:
Let the number of G-C pairs be x, and the number of A-T pairs be y.
From the problem, we have the equation: 3x + 2y = 130.
Additionally, the total number of base pairs should add up to the total number of base pairs, which we can estimate by testing the options.
4. Checking the Options: After substituting the values from the given options, we find that the correct combination is:
