Question

For a double-strand DNA, one strand is given below: The amount of energy required to split the double-strand DNA into two single strands is . kcal mol........\(^{-1}\). [Given: Average energy per H-bond for A-T base pair = 1 kcal mol\(^{-1}\), G-C base pair = 1.5 kcal mol\(^{-1}\), and A-U base pair = 1.25 kcal mol\(^{-1}\). Ignore electrostatic repulsion between the phosphate groups]

Hint:

To calculate the energy required to break DNA strands, use the energy contributions of each base pair and multiply by the number of bonds involved.

Answer 1

1. Count the base pairs: - Number of A-T pairs = 7. - Number of G-C pairs = 6. 2. Energy for A-T base pairs: \[ \text{Energy} = 7 \times 2 \times 1 \, \text{kcal/mol} = 14 \, \text{kcal/mol}. \] 3. Energy for G-C base pairs: \[ \text{Energy} = 6 \times 2 \times 1.5 \, \text{kcal/mol} = 27 \, \text{kcal/mol}. \] 4. Total energy: \[ \text{Total energy} = 14 + 27 = 41 \, \text{kcal/mol}. \]