Question

If the base pairs in a DNA strand were held together with covalent bonds instead of hydrogen bonds, how would cells have to operate differently? A) New DNA would need to be made each time the strand was opened. B) The cell would have to take in and use more energy in order to break the covalent bonds. C) Each time the DNA strand opened the cell would need to replace the nitrogenous bases. D) The cell could only open and close the DNA strand when it replicated.

Answer 1

 the option b is correct because covalent bond is stronger than hydrogen bond ...The cell would have to take in and use more energy in order to break the covalent bonds.

Answer 2

The right answer is B) The cell would have to take in and use more energy in order to break the covalent bonds.

Hydrogen bonds are the chemical mechanism that governs the complementarity of the bases of DNA. This correspondence is unique thanks to the geometry of the hydrogen donor atoms and the acceptors that form the bases.

The (hydrophobic) bases are stacked inside the double helix of DNA; their plane is perpendicular to the axis of the double helix. The outside (phosphate and sugar) is hydrophilic.

The hydrogen bonds between the bases of one strand and the bases of the other strand keep the 2 strands united.

One purine on one strand necessarily binds to a pyrimidine on the other strand. As a corollary, the number of purine residues is equal to the number of pyrimidine residues.

* A binds to T (by 2 hydrogen bonds).

* G binds to C (via 3 hydrogen bonds: more stable bond: 5.5 kcal vs 3.5 kcal).