Monomers & Polymers as Biological Molecules (College Board AP® Biology)

Hydrolysis & Dehydration Synthesis

Polymers and Monomers in Biological Systems

• Polymers play an important role in biological molecules

• The term 'biological macromolecule' is often used to describe biological polymers

• A polymer is made of a large number of monomers joined together

• Many metabolic processes involve the breaking and making of biological macromolecules

Dehydration Synthesis

• Is the process by which two molecules of monomer join together with a covalent bond

  • A molecule of water is given off as a byproduct

    • Hence the term 'dehydration'

  • This water molecule joins the cell cytosol and forms part of the cell's normal water content

• Two monomers joined together are called a dimer, 3 monomers is a trimer etc.

• Many monomers joined together form a polymer

• One large molecule is produced (synthesized)

• When this happens many times over, a polymer begins to form, with the production of a water molecule each time a new monomer joins the polymer

• This is a common theme in the building of many different types of biological macromolecules

• Dehydration synthesis is sometimes referred to as condensation

Biological polymers table

The basis of dehydration synthesis diagram

Written and symbolic illustrations of the removal of water to form a covalent bond between 2 or more monomers during a dehydration synthesis reaction

Hydrolysis

• Hydrolysis means ‘lyze’ (to break) and ‘hydro’ (with water)

• In the hydrolysis of polymers, covalent bonds are broken when water is added

Written and symbolic illustrations of the addition of water to break down covalent bond/s during a hydrolysis reaction

Summary table of the covalent bonds formed by dehydration synthesis and broken by hydrolysis