Hydrogen bonds are responsible for specific base-pair formation in the DNA double helix and a major factor to the stability of the DNA double helix structure. A hydrogen-bond donor includes the hydrogen atom and the atom to which it is most tightly linked with.

Hydrogen bonding stabilizes DNA double helices across the helix axis but not in the direction of the axis 1. In DNA, the deoxyribose-phosphate backbone can act as hydrogen-bond acceptor only through phosphate and sugar oxygen atoms.

This type of bond can occur in inorganic molecules such as water and in organic molecules like DNA and proteins. Intramolecular hydrogen bonding is partly responsible for the secondary and tertiary structures of proteins and nucleic acids.

Because the hydrogen is slightly positive, it will be attracted to neighboring negative charges. When this happens, a weak interaction occurs between the δ+ of the hydrogen from one molecule and the δ– charge on the more electronegative atoms of another molecule, usually oxygen or nitrogen, or within the same molecule.

The slight positive charges on the hydrogen atoms in a water molecule attract the slight negative charges on the oxygen atoms of other water molecules. Hydrogen bonds are formed easily when two water molecules come close together, but are easily broken when the water molecules move apart again.

Without hydrogen bonds, water molecules would move faster more rapidly, with less input of heat energy, causing the temperature to increase more for each calorie of heat added.

Hydrogen bonds between nitrogenous bases in nucleotides on the two strands of DNA (guanine pairs with cytosine, adenine with thymine) give rise to the double-helix structure that is crucial to the transmission of genetic information.

Covalent Bonds – Disulfide Bridges

Weak bonds may be easily broken but they are very important because they help to determine and stabilize the shapes of biological molecules. Hydrogen bonds keep complementary strands of DNA together. Hydrogen bonds participate in enzymic catalysis.

Covalent bond

The bond is labeled as “the strongest in organic chemistry,” because fluorine forms the strongest single bond to carbon. Carbon–fluorine bonds can have a bond dissociation energy (BDE) of up to 130 kcal/mol. The BDE (strength of the bond) of C-F is higher than other carbon–halogen and carbon–hydrogen bonds.

The highest and thus the shortest are the triple bonds. There are then double bonds between the triple and single bonds that are of intermediate strength. And ultimately, there are weaker single bonds than the other two….Thank you.

Bonds involving hydrogen can be quite short; the shortest bond of all, H–H, is only 74 pm. The covalent radius of an atom is determined by halving the bond distance between two identical atoms.