Learning Objectives

By the end of this section, you will be able to do the following:

Understand macromolecule synthesisExplain dehydration (or condensation) and hydrolysis reactions

As did you do it learned, organic macromolecules are huge molecules, essential for life, that are constructed from smaller organic molecules. There are four major biological macromolecule classes (carbohydrates, lipids, proteins, and also nucleic acids). Every is crucial cell component and performs a vast array the functions. Combined, these molecules make up the bulk of a cell’s dried mass (recall the water provides up the bulk of its complete mass). Biological macromolecules are organic, meaning they save carbon. In addition, they might contain hydrogen, oxygen, nitrogen, and extr minor elements.

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Dehydration Synthesis

Most macromolecules room made from single subunits, or building blocks, called monomers. The monomers incorporate with each various other using covalent bonds to form larger molecules known as polymers. In doing so, monomers release water molecules together byproducts. This kind of reaction is dehydration synthesis, which means “to put together while losing water.”

In the dehydration synthesis reaction above, two glucose molecules connect to type the disaccharide maltose. In the process, it creates a water molecule.


Dehydration and also hydrolysis reactions space catalyzed, or “sped up,” by specific enzymes; dehydration reactions involve the development of new bonds, request energy, while hydrolysis reactions break bonds and also release energy. These reactions are similar for most macromolecules, but each monomer and also polymer reaction is specific for that class. For example, catalytic enzyme in the digestive mechanism hydrolyze or breakdown the food we ingest into smaller molecules. This permits cells in our body to quickly absorb nutrients in the intestine. A certain enzyme breaks down each macromolecule. Because that instance, amylase, sucrase, lactase, or maltase breakdown carbohydrates. Enzymes dubbed proteases, such as pepsin and also peptidase, and also hydrochloric acid malfunction proteins. Lipases break down lipids. These damaged down macromolecules provide energy for cellular activities.

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Section Summary

Proteins, carbohydrates, nucleic acids, and lipids space the four major classes of biological macromolecules—large molecules vital for life that are developed from smaller sized organic molecules. Macromolecules are consisted of of single units scientists call monomers that space joined by covalent bonds to form larger polymers. The polymer is much more than the sum of the parts: it acquires brand-new characteristics, and leads come an osmotic press that is much reduced than that created by the ingredients. This is an essential advantage in keeping cellular osmotic conditions. A monomer joins with one more monomer v water molecule release, causing a covalent link forming. Scientists contact these dehydration or condensation reactions. Once polymers malfunction into smaller sized units (monomers), they use a water molecule for each bond damaged by this reactions. Such reactions are hydrolysis reactions. Dehydration and also hydrolysis reaction are similar for all macromolecules, however each monomer and polymer reaction is details to that class. Dehydration reactions typically require an investment of energy for new bond formation, while hydrolysis reactions commonly release power by break bonds.

Review Questions

Dehydration synthesis leads to development of

monomerspolymerswater and polymersnone that the above


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

hydrolysisdehydrationcondensationcovalent bond

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