Biological macromolecules are large molecules necessary for life and
include carbohydrates, lipids, nucleic acids, and proteins.
LEARNING OBJECTIVE [ edit ]
State the four major classes of biological macromolecules.
KEY POINTS [ edit ]
Biological macromolecules perform a wide array of functions and are important cell components.
Biological macromolecules are considered to be polymers that are synthesized via dehydration
reactions from smaller components called monomers.
Biological macromolecules can be broken down into simpler components via hydrolysis reactions.
TERMS [ edit ]
monomer
A relatively small molecule which can be covalently bonded to other monomers to form a
polymer.
hydrolysis
A chemical process of decomposition involving the splitting of a bond by the addition of water.
polymer
A long or larger molecule consisting of a chain or network of many repeating units formed by
chemically bonding together many identical or similar small molecules called monomers.
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Food provides the body with thenutrients it needs to survive. Many of these critical nutrients
are biologicalmacromolecules, or large molecules. The term macromolecule was first coined
by the Nobel laureate Hermann Staudinger in the 1920's. Staudinger was the first to propose
that many large biological molecules are
build by covalently linking smaller
biological molecules together.
Synthesizing Biological
Macromolecules
The biological macromolecules that will be
discussed in detail throughout this section
are necessary for life because they act as
critical components of cell structure and
function. Most biological macromolecules
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are polymers. Polymers are any molecules
that are constructed by linking together many smaller molecules, called monomers. Typically
the monomers in a polymer tend to be of limited variety; the same or similar molecules
linked to together over and over again to build up the macromolecule.
Almost all biological monomers are linked together during polymer synthesis by
a reaction called a dehydration reaction(in the past, it was also called
a condensation reaction.) The process used to breakdown biological macromolecules into
their simpler components is termed hydrolysis.
Biological macromolecules all contain carbon in a ring or chain form, so they are classified
as organic molecules. They usually also contain hydrogen and oxygen, and often contain
nitrogen and additional minor elements.
Sources of biological macromolecules
Foods such as bread, fruit, and cheese are rich sources of biological macromolecules.
Four Classes of Biological Macromolecules
There are four major classes of biological macromolecules:
1. carbohydrates
2. lipids
3. proteins
4. nucleic acids.
Each of these macromolecules is an important cell component and performs a wide array of
functions within the cell. In combination, these biological macromolecules make up the
majority of a cell's dry mass. Water molecules make up the majority of a cell's complete mass.
It is important to remember that all of the molecules both inside and outside of cells are
situated in, and all the reactions of biological systems are occurring in, a water-based
(aqueous) environment.
Interactive: Monomers and Polymers
Carbohydrates, proteins, and nucleic acids are built from small molecular units that are connected to
each other by strong covalent bonds. The small molecular units are called monomers (mono means one,
or single), and they are linked together into long chains called polymers (poly means many, or multiple).
Each different type of macromolecule, except lipids, is built from a different set of monomers that
resemble each other in composition and size. Lipids are not polymers, because they are not built from
monomers (units with similar composition).