Hydrogen Bond

Definition

A hydrogen bond is a type of dipole-dipole attraction that occurs when a hydrogen atom covalently bonded to a highly electronegative element, such as oxygen, nitrogen, or fluorine, is attracted to another nearby highly electronegative element. This intermolecular force plays a crucial role in the structure and function of various biological molecules and processes.

5 Must Know Facts For Your Next Test

1. Hydrogen bonds are typically stronger than other dipole-dipole interactions, but weaker than covalent or ionic bonds.
2. Hydrogen bonds play a crucial role in the secondary and tertiary structures of proteins, as well as the double-helix structure of DNA.
3. Water molecules can form multiple hydrogen bonds, which contribute to water's high boiling point and ability to dissolve many polar and ionic substances.
4. Hydrogen bonding is responsible for the cohesive and adhesive properties of water, allowing it to climb up narrow tubes against gravity (capillary action).
5. Disruption of hydrogen bonds can have significant impacts on the structure and function of biological molecules, leading to changes in their properties and behaviors.

Review Questions

• Explain the role of hydrogen bonding in the structure and function of DNA.
  • Hydrogen bonding is essential for the stability and structure of DNA. The complementary base pairing between adenine and thymine, and guanine and cytosine, is maintained by hydrogen bonds. These hydrogen bonds hold the two strands of the DNA double helix together, allowing for the storage and transmission of genetic information. Additionally, hydrogen bonding contributes to the secondary and tertiary structures of DNA, which are crucial for its biological functions, such as replication, transcription, and regulation of gene expression.
• Describe how hydrogen bonding influences the physical and chemical properties of water.
  • Hydrogen bonding is responsible for many of the unique properties of water. The ability of water molecules to form multiple hydrogen bonds with each other leads to water's high boiling point, surface tension, and cohesive and adhesive properties. Hydrogen bonding also allows water to act as a universal solvent, capable of dissolving a wide range of polar and ionic substances. These properties are essential for water's role in various biological processes, such as transport, temperature regulation, and maintaining the structure and function of biomolecules.
• Analyze the importance of hydrogen bonding in the structure and function of proteins.
  • Hydrogen bonding is a critical factor in the folding and stability of protein structures. The formation of hydrogen bonds between the carbonyl oxygen and amide hydrogen atoms of the polypeptide backbone allows for the formation of secondary structures, such as alpha-helices and beta-sheets. These secondary structures then interact through additional hydrogen bonding to form the tertiary structure of the protein, which is essential for its biological function. Disruption of these hydrogen bonds, through changes in pH or temperature, can lead to protein denaturation and the loss of their native structure and function. The role of hydrogen bonding in protein structure and stability highlights its importance in maintaining the proper conformation and activity of these essential biomolecules.

Related terms

Dipole-Dipole Interaction: An intermolecular force that occurs between two polar molecules, where the partially positive end of one molecule is attracted to the partially negative end of another molecule.

Electronegativity:

The ability of an atom to attract shared electrons in a covalent bond, which determines the polarity of the bond and the potential for hydrogen bond formation.

Intermolecular Force: The attractive or repulsive forces that exist between molecules, which influence the physical and chemical properties of substances.