Learning Objectives

By the end of this section, you will have the ability to do the following:

Understand macromolecule synthesisExplain dehydration (or condensation) and hydrolysis reactions

As did you do it learned, organic macromolecules are large molecules, essential for life, that are built from smaller organic molecules. There are four major biological macromolecule classes (carbohydrates, lipids, proteins, and also nucleic acids). Each is vital cell component and also performs a broad array that functions. Combined, this molecules comprise the bulk of a cell’s dry mass (recall the water renders up the majority of its finish mass). Biological macromolecules space organic, an interpretation they save carbon. In addition, they might contain hydrogen, oxygen, nitrogen, and additional minor elements.

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Dehydration Synthesis

Most macromolecules room made from single subunits, or structure blocks, referred to as monomers. The monomers incorporate with each other using covalent bonds to type larger molecules well-known as polymers. In doing so, monomers relax water molecules as byproducts. This form of reaction is dehydration synthesis, which way “to put together while losing water.”

In the dehydration synthetic reaction above, 2 glucose molecules link to kind the disaccharide maltose. In the process, it develops a water molecule.


Dehydration and also hydrolysis reactions space catalyzed, or “sped up,” by particular enzymes; dehydration reactions involve the development of brand-new bonds, request energy, if hydrolysis reactions break bonds and also release energy. This reactions are comparable for many macromolecules, yet each monomer and also polymer reaction is particular for that class. For example, catalytic enzyme in the digestive device hydrolyze or break down the food us ingest right into smaller molecules. This permits cells in our human body to conveniently absorb nutrient in the intestine. A particular enzyme breaks under each macromolecule. Because that instance, amylase, sucrase, lactase, or maltase breakdown carbohydrates. Enzymes called proteases, such together pepsin and peptidase, and hydrochloric acid break down proteins. Lipases failure lipids. These damaged down macromolecules administer energy for cellular activities.

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Section Summary

Proteins, carbohydrates, nucleic acids, and lipids are the four significant classes of organic macromolecules—large molecules vital for life that are built from smaller organic molecules. Macromolecules are consisted of of solitary units scientists call monomers that are joined through covalent bonds to kind larger polymers. The polymer is an ext than the amount of that is parts: it acquires new characteristics, and leads to an osmotic pressure that is much lower than that developed by that is ingredients. This is an important advantage in maintaining cellular osmotic conditions. A monomer join with another monomer v water molecule release, leading to a covalent link forming. Scientists speak to these dehydration or condensation reactions. Once polymers malfunction into smaller units (monomers), they use a water molecule for each bond broken by these reactions. Together reactions are hydrolysis reactions. Dehydration and also hydrolysis reaction are similar for all macromolecules, yet each monomer and polymer reaction is particular to its class. Dehydration reactions generally require an invest of power for brand-new bond formation, when hydrolysis reactions commonly release power by break bonds.

Review Questions

Dehydration synthesis leads to development of

monomerspolymerswater and polymersnone that the above


During the break down of polymers, which of the adhering to reactions takes place?

hydrolysisdehydrationcondensationcovalent bond

The complying with chemical reactants create the ester ethyl ethanoate (C4H8O2):