Interactions in Large Biomolecules (College Board AP® Chemistry)

Interactions in Large Biomolecules

• Intermolecular interactions are also found in large biomolecules like proteins, carbohydrates and lipids

• These interactions are possible either between biomolecules or within different regions of the same molecule

• For example, double-helix DNA molecules are held together by hydrogen bonds

  • The hydrogen bonding involves the nitrogenous base components between each DNA molecule strand

Hydrogen Bond in DNA Strands

Double helix DNA strands show the hydrogen bonds between the nitrogenous base components of each strand

• Interaction between different biomolecules is seen between:

  • The hydrophobic —“water fearing”— tails of lipids and water molecules, which makes lipids insoluble in water due to the lack of hydrogen bond

  • The hydrophilic — “water loving” — interaction between carbohydrates and water molecules, which makes them soluble in water

Lipids Interaction with Water

Nonpolar oil molecules do not mix with water due to a lack of polar hydrogen

Carbohydrate Interaction with Water

The presence of polar hydrogen atoms on sugar molecules makes glucose dissolve in water