Question

Discuss the importance of hydrogen bonding in biological systems. Use proteins and nucleic acids as examples.

Short answer

Hydrogen bonding is essential in biological systems as it helps maintain the structure and functionality of proteins and nucleic acids. In proteins, it leads to the formation of secondary structures like alpha-helices and beta-sheets, which contribute to proteins' overall structure and function. In nucleic acids, hydrogen bonds allow for bases to pair in the DNA double helix, making the duplication of DNA possible during replication.

Step-by-step solution

Understanding the Nature of Hydrogen Bonding

Hydrogen bonds are fairly weak attractions that occur between the slightly negative and positive polar covalent bonds found in molecules. In this case, a hydrogen atom bonded to a highly electronegative atom such as nitrogen or oxygen, creates a partial positive charge which can be attracted to a partial negative charge on a different molecule to form a hydrogen bond. They play a pivotal role in the structure and function of biological molecules.

Hydrogen Bonding in Proteins

In proteins, hydrogen bonds are vital for maintaining the structure of the protein. The hydrogen bonds in proteins occur between the carbonyl oxygen and the amino hydrogen within the polypeptide backbone. This leads to the creation of alpha-helices and beta-sheets, the secondary structures of proteins that are crucial for protein's overall tertiary structure and ultimately, its function. Without hydrogen bonding, these structures would not be able to form.

Hydrogen Bonding in Nucleic Acids

In nucleic acids, hydrogen bonds are responsible for the pairing of bases in the DNA double helix. Adenine (A) pairs with thymine (T) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds. This characteristic allows the DNA to maintain its structure and, importantly, allows for the duplication of DNA during replication before cell division. Without hydrogen bonds, the double helix structure would not be possible, and DNA replication could not occur in the same way.