Biological molecules are built of atoms, just as all matter in the universe is built of atoms. Atoms themselves are made up of protons, neutrons, and electrons. Atoms combine to form compounds, which occur when two or more elements bond together. These chemical bonds can be formed either by electrostatic attraction to create ionic compounds or by the sharing of electrons to form molecular compounds. Biological molecules are mainly formed from combinations of carbon, hydrogen, oxygen, and nitrogen atoms, although phosphorus, calcium, potassium, and other trace elements are also important to cell function. Of the four main biological elements, carbon has the most significant role because it has four valence electrons and can form four strong covalent bonds. Thus, carbon has the ability to form an extensive variety of high-molecular-weight macromolecules. These macromolecules contain specific structures that depend upon noncovalent bonds, such as hydrogen bonds, to maintain stability.
At A Glance
Atoms are made up of protons, neutrons, and electrons in varying configurations that compose all matter in the universe.
- Electrons are shared between atoms in a compound formed by a covalent bond. They are transferred from one atom to another in an ionic bond, and a van der Waals attraction is created when a weak, noncovalent bond occurs between atoms whose outer electron clouds barely touch.
Compounds form when two different atoms of elements bind together either with covalent bonds, which occur when two atoms share a pair of valence electrons, or with ionic bonds, which occur when ions of opposite charges attract each other.
Biological molecules are primarily comprised of carbon, hydrogen, oxygen, and nitrogen, as well as trace amounts of other elements, such as calcium, potassium, and iron.
Isotopes are different forms of the same element that vary in the number of neutrons and are employed in biological research and as medical diagnostic tools.
Noncovalent bonds, such as hydrogen bonds, van der Waals forces, ionic bonds, and hydrophobic bonds, play an important role in forming the structures of biological molecules.
- Carbon's ability to form four different strong covalent bonds is responsible for the extensive variety of biological macromolecules.