The weak chemical bonds important in holding the DNA double helix together is the: ionic bond polar covalent nonpolar covalent hydrogen bond

Identifying the Type of Bond

In the structure of DNA, the double helix is stabilized by various types of bonds. The question asks about the weak chemical bonds specifically important in holding the DNA double helix together.

1. Ionic Bonds: These are formed by the electrostatic attraction between oppositely charged ions and are generally stronger than the weak interactions we typically discuss in the context of the DNA double helix.

2. Polar Covalent Bonds: These occur due to the unequal sharing of electrons between atoms, leading to partial charges. While polar covalent bonds are significant in the overall structure of molecules, they are not characterized as weak bonds in the context of the double helix.

3. Nonpolar Covalent Bonds: These involve equal sharing of electrons and are strong bonds. They contribute to the backbone of DNA, specifically in the sugar-phosphate backbone.

4. Hydrogen Bonds: This type of bond is crucial for the stability of the DNA structure. Hydrogen bonds are relatively weak interactions that occur between the nitrogenous bases (adenine pairs with thymine and cytosine pairs with guanine), allowing the strands of the double helix to separate during DNA replication and transcription.

Final Answer

The weak chemical bonds important in holding the DNA double helix together are hydrogen bonds.