Dehydration synthesis or a condensation reaction (video) | Khan Academy
The difference between dehydration synthesis and hydrolysis is that in one, bonds are being formed, while in the other bonds are being destroyed. Dehydration. In dehydration synthesis, monomers combine with each other via covalent bond that links the two monomeric sugars (monosaccharides) together to form the Hydrolysis reactions result in the breakdown of polymers into monomers by using a enzyme: a globular protein that catalyses a biological chemical reaction. Dehydration synthesis refers to the formation of larger molecules from Hydrolysis is catalyzed by a large group of enzymes called hydrolases. Which of these involves the formation of an ester linkage through dehydration synthesis ?.
One common polyester is polyethylene terephthalate PET and gives its name to a class of recyclable bottles. PET is formed by dehydration synthesis from two monomers — ethylene glycol and teraphthalic acid. In biological systems, dehydration synthesis reactions occur in every cell, especially since it is important for the formation of ATP. Nearly all biopolymers are also derived from this reaction. Formation of Glycosidic Bonds Glycosidic bonds are covalent bonds formed between a carbohydrate and any other molecule.
Many of these involve a dehydration reaction. When maltose is formed from glucose, there is a glycosidic bond between two glucose molecules with the release of one molecule of water. Long polymers of glucose can be formed in a similar manner through a series of dehydration reactions to give rise to starch, cellulose or glycogen based on the position of the glycosidic bonds.
Other disaccharides like sucrose and lactose are also formed through dehydration reactions between two monosaccharides.
Additionally, glycosidic bonds are also involved when a carbohydrate is modified. Here, a glucose molecule is reacting with methanol to give rise to ethyl glucoside. Triglyceride Formation One of the intermediates of carbohydrate and fat metabolism is acetyl coA, a molecule where a two-carbon acetyl group is attached to coenzyme A.
These fatty acids then form triglycerides, which are an important energy storage molecule. Triglycerides derive their name from the fact that all three hydroxyl groups on glycerol undergo esterification with fatty acids. Each of the three fatty acids undergoes a dehydration reaction with the alcohol moieties on glycerol to generate one molecule of triglyceride.
One of the main reasons why triglycerides are considered a better storage medium than carbohydrates is their high energy density. They have a larger proportion of carbon atoms that can undergo oxidation and contain fewer oxygen molecules because fatty acids are generated from hydrocarbons. The removal of three water molecules in the process of forming a triglyceride further increases the energy density of the molecule. In this image, R1, R2 and R3 refer to long chain hydrocarbons, each of which is attached to a carboxylic acid functional group.
Hydrolysis Hydrolysis is the reverse of a dehydration reaction because it involves the breaking of a covalent bond through the addition of a molecule of water. Hydrolysis is catalyzed by a large group of enzymes called hydrolases. Among the most commonly known hydrolases are digestive enzymes. Digestion begins from the mouth, where salivary amylase breaks down starch molecules.
This is why extended chewing of starchy foods gives rise to a sweet taste in the mouth. The action of salivary amylase generates monosaccharides. This is followed by the action of proteases in the stomach that begin the process of breaking peptide bonds in proteins. Digestion is continued by hydrolytic enzymes from the pancreas and small intestine acting on lipids, carbohydrates, nucleic acids and proteins. Each of these hydrolases has a specific name depending on the nature of its substrate.
For instance, lipases act on lipids and nucleases on nucleic acids.
A protease that severs peptide bonds from one end of the protein is called an exopeptidase and those that act on internal bonds are called endopeptidases. Similar enzymes are also present for intracellular digestion within lysosomes.
Additionally, there are specific enzymes that can reverse the post-translational modifications of proteins, such as phosphatases.
These enzymes remove the phosphate group attached to a protein through a hydrolysis reaction. Similarly, ATPase enzymes catalyze the hydrolysis of the terminal phosphodiester bond in ATP, and are important for releasing the energy stored in the molecule. We essentially had some hydronium.
We had a hydrogen proton out here before and we still do. Now it's attached to a water, so we've take a proton and we've given back a proton, so we have a net-net kind of added charge or taken charge away from the system. But the important thing that we just saw is as these two things essentially attached, we lost a water molecule, or I guess net-net, this system lost a water molecule.
It took up a charge to do it, to build that water molecule, but the thing that really kind of escaped from both of these two molecules is this, is this right over here. This H is this H, this oxygen is this oxygen. And this hydrogen is this hydrogen right over here.
And so this type of a reaction in which we're synthesizing a more complex molecule, a longer chain of glucose molecules, this is called a dehydration synthesis. So what we just did, this right over here is called a dehydration synthesis. Why are we calling it a dehydration synthesis?
Well, we've just taken a water out. If you imagine losing water, we talk about you're getting dehydrated.
Dehydration synthesis or a condensation reaction
Well, we put two things together. We synthesized a larger molecule. Sometimes this would be called a condensation reaction. And by doing this, these two glucose molecules are able to form a disaccharide now.
So each individually, they were monosaccharides, so this one on the right, that's a monosaccharide. What does monosaccharide mean? Well, it means, mono means single or one and saccharide comes from the Greek word for sugar. The Greek word for sugar is, I'm gonna mispronounce it, is sakcharon.
When people talk about something being saccharine, they're saying something is very, very sweet. The Greek word for sugar is sakcharon.
So saccharide means it's a sugar, it's a single sugar. So that meaning there, sugar. And the general term saccharide refers to not just the simple sugars, monosaccharides, but it could mean two of these things put together. And there's other simple sugars, fructose and others.
Synthesis of Biological Macromolecules - Biology LibreTexts
Or it could mean a huge number of these put together. You could have polysaccharides. And that whole class, saccharides, we also associate with carbohydrates. Now we went from two monosaccharides to right over here. During these reactions, the polymer is broken into two components: In the hydrolysis reaction shown here, the disaccharide maltose is broken down to form two glucose monomers with the addition of a water molecule.
These reactions are similar for most macromolecules, but each monomer and polymer reaction is specific for its class. For example, in our bodies, food is hydrolyzed, or broken down, into smaller molecules by catalytic enzymes in the digestive system. This allows for easy absorption of nutrients by cells in the intestine. Each macromolecule is broken down by a specific enzyme. For instance, carbohydrates are broken down by amylase, sucrase, lactase, or maltase.
Proteins are broken down by the enzymes pepsin and peptidase, and by hydrochloric acid. Lipids are broken down by lipases.
Breakdown of these macromolecules provides energy for cellular activities.