What type of reaction links monomers to make polymers

In addition, they may contain hydrogen, oxygen, nitrogen, and additional minor elements. Most macromolecules are made from single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.

In doing so, monomers release water molecules as byproducts. In a dehydration synthesis reaction Figure , the hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a water molecule. At the same time, the monomers share electrons and form covalent bonds. As additional monomers join, this chain of repeating monomers forms a polymer. Different monomer types can combine in many configurations, giving rise to a diverse group of macromolecules. Even one kind of monomer can combine in a variety of ways to form several different polymers.

For example, glucose monomers are the constituents of starch, glycogen, and cellulose. Polymers break down into monomers during hydrolysis. A chemical reaction occurs when inserting a water molecule across the bond. Breaking a covalent bond with this water molecule in the compound achieves this Figure. These reactions are similar for most macromolecules, but each monomer and polymer reaction is specific for its class.

For example, catalytic enzymes in the digestive system hydrolyze or break down the food we ingest into smaller molecules. This allows cells in our body to easily absorb nutrients in the intestine. A specific enzyme breaks down each macromolecule. For instance, amylase, sucrase, lactase, or maltase break down carbohydrates. Enzymes called proteases, such as pepsin and peptidase, and hydrochloric acid break down proteins.

Lipases break down lipids. The terms polymer and monomer were derived from the Greek roots poly many , mono one and meros part. Recognition that polymeric macromolecules make up many important natural materials was followed by the creation of synthetic analogs having a variety of properties.

Indeed, applications of these materials as fibers, flexible films, adhesives, resistant paints and tough but light solids have transformed modern society. Some important examples of these substances are discussed in the following sections. There are two general types of polymerization reactions: addition polymerization and condensation polymerization.

In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers. Ethylene molecules are joined together in long chains. Many natural materials—such as proteins, cellulose and starch, and complex silicate minerals—are polymers. Artificial fibers, films, plastics, semisolid resins, and rubbers are also polymers. More than half the compounds produced by the chemical industry are synthetic polymers.

The bond lines extending at the ends in the formula of the product indicate that the structure extends for many units in each direction. Notice that all the atoms—two carbon atoms and four hydrogen atoms—of each monomer molecule are incorporated into the polymer structure.

Because displays such as the one above are cumbersome, the polymerization is often abbreviated as follows:. During the polymeriation of ethene, thousands of ethene molecules join together to make poly ethene - commonly called polythene. The reaction is done at high pressures in the presence of a trace of oxygen as an initiator. Note that all the monomers have carbon-to-carbon double bonds. Many polymers are mundane e. The oxygen reacts with some of the ethene to give an organic peroxide. Organic peroxides are very reactive molecules containing oxygen-oxygen single bonds which are quite weak and which break easily to give free radicals.

You can short-cut the process by adding other organic peroxides directly to the ethene instead of using oxygen if you want to. The type of the free radicals that start the reaction off vary depending on their source. One pair is held securely on the line between the two carbon nuclei in a bond called a sigma bond.

It would be helpful - but not essential - if you read about the structure of ethene before you went on. If the diagram above is unfamiliar to you, then you certainly ought to read this background material. Don't worry that we've gone back to a simpler diagram. The sigma bond between the carbon atoms isn't affected by any of this.

The other electron returns to the right hand carbon. You can show this using "curly arrow" notation if you want to:. Most macromolecules are made from single subunits, or building blocks, called monomers. The monomers combine with each other via covalent bonds to form larger molecules known as polymers.

In doing so, monomers release water molecules as byproducts. In a dehydration synthesis reaction between two un-ionized monomers, such as monosaccharide sugars, the hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a molecule of water in the process. The removal of a hydrogen from one monomer and the removal of a hydroxyl group from the other monomer allows the monomers to share electrons and form a covalent bond.

Thus, the monomers that are joined together are being dehydrated to allow for synthesis of a larger molecule. A dehydration synthesis reaction involving un-ionized moners.. In the process, a water molecule is formed. When the monomers are ionized, such as is the case with amino acids in an aqueous environment like cytoplasm, two hydrogens from the positively-charged end of one monomer are combined with an oxygen from the negatively-charged end of another monomer, again forming water, which is released as a side-product, and again joining the two monomers with a covalent bond.

A dehydration synthesis reaction involving ionized monomers. In the process a water molecule is formed. As additional monomers join via multiple dehydration synthesis reactions, the chain of repeating monomers begins to form a polymer.

Different types of monomers can combine in many configurations, giving rise to a diverse group of macromolecules. Three of the four major classes of biological macromolecules complex carbohydrates, nucleic acids, and proteins , are composed of monomers that join together via dehydration synthesis reactions.

Complex carbohydrates are formed from monosaccharides, nucleic acids are formed from mononucleotides, and proteins are formed from amino acids. There is great diversity in the manner by which monomers can combine to form polymers. For example, glucose monomers are the constituents of starch, glycogen, and cellulose. These three are polysaccharides, classified as carbohydrates, that have formed as a result of multiple dehydration synthesis reactions between glucose monomers.

However, the manner by which glucose monomers join together, specifically locations of the covalent bonds between connected monomers and the orientation stereochemistry of the covalent bonds, results in these three different polysaccharides with varying properties and functions.

In nucleic acids and proteins, the location and stereochemistry of the covalent linkages connecting the monomers do not vary from molecule to molecule, but instead the multiple kinds of monomers five different monomers in nucleic acids, A, G, C, T, and U mononucleotides; 21 different amino acids monomers in proteins are combined in a huge variety of sequences. Each protein or nucleic acid with a different sequence is a different molecule with different properties.

Hydrolysis reactions result in the breakdown of polymers into monomers by using a water molecule and an enzymatic catalyst.

During these reactions, the polymer is broken into two components. If the components are un-ionized, one part gains a hydrogen atom H- and the other gains a hydroxyl group OH— from a split water molecule. This is what happens when monosaccharides are released from complex carbohydrates via hydrolysis. Hydrolysis reaction generating un-ionized products. One glucose gets a hydroxyl group at the site of the former covalent bond, the other glucose gets a hydrogen atom.

This is the reverse of the dehydration synthesis reaction joining these two monomers. If the components are ionized after the split, one part gains two hydrogen atoms and a positive charge, the other part gains an oxygen atom and a negative charge. This is what happens when amino acids are released from protein chains via hydrolysis. Hydrolysis reaction generating ionized products.