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The following points highlight the three main types of bonds in DNA replication. The types are: 1. Covalent and Ionic Bonds 2. Hydrogen Bonds 3. Weak Chemical Bonds.
Type # 1. Covalent and Ionic Bonds:
Atoms can attain a more stable arrangement of electrons in their outermost shell by interacting with one another. An ionic bond results from transfer of electrons from one atom to the other. A covalent bond is formed when electrons are shared between atoms. Often covalent bonds form with a partial transfer that leads to unequal sharing of electrons, resulting in a polar covalent bond.
Van der Waals Forces:
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At very short distances any two atoms show a weak bonding interaction due to their fluctuating electrical charges. If the two atoms are too close together, however, they repel each other very strongly. Each atom has a characteristic Van der Waals radius. The contact distance between any two atoms is the sum of their Van der Waals radii.
Two atoms will be attracted to each other by Van der Waals forces until the distance between them equals the sum of their Van der Waals radii. Although they are individually very weak, Van der Waals attractions can become important when two macromolecular surfaces fit very close together.
Type # 2. Hydrogen Bonds:
The hydrogen bonds form when a hydrogen atom is “sandwiched” between two electron-attracting atoms (usually oxygen or nitrogen). Hydrogen bonds are strongest when the three atoms are in a straight line.
Examples of hydrogen bonds are seen in DNA and RNA. There are three hydrogen bonds between G and C pairs, two hydrogen bonds between A and T pairs. Amino acids in polypeptide chains are also hydrogen-bonded together.
Molecules that can form hydrogen bonds with each other can also form hydrogen bonds with water molecules. Because of this competition with water molecules, the hydrogen bonds formed between two molecules dissolved in water are relatively weak.
Type # 3. Weak Chemical Bonds:
Organic molecules can interact with other molecules through short-range non-covalent forces. Weak chemical bonds have less than half the strength of a strong covalent bond. However, they are strong enough to provide tight binding only when many of them are formed simultaneously.
