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Hydrolysis and Dehydration Synthesis

Hydrolysisreactions are chemical reactions that break down a larger molecule into smallsubunits, in order to digest the larger molecule. The name hydrolysis comes from the Greekwords meaning water and break. When hydrolysis occurs when a covalent bond is brokenbetween the glucose subunits in the polysaccharides chain at the same time the breaking of a

water molecule. When a person eats plant starch the molecule is broken down with in theintestine so that the body can absorb the separate glucose molecules with in the polysaccharidechain. In the picture below the polysaccharide is hydrolyzed to form the maltose in part (a) andthen in part (b) the it is hydrolyzed into glucose to be used for cell energy. When the covalentbonds breaks between the subunits a molecule of water is split. This creates an additon of ahydrogen atom and a hydroxyl group to the end of the subunits that are released afterhydrolysis takes place.

The hydrolysis of starch

The plant starch is now glucose molecules that can be absorbed by the intestines. The bloodthat runs through the intestines picks up the glucose molecules and allows them to travel toskeletal muscles and the liver. Now the tissue cells of the skeletal muscles and the liver take theglucose out of the blood. Theses cells either use it for energy or they can store the glucose. Inorder to store glucose it needs to be in the form of glycogen. To make glycogen out of theglucose molecules the cells will have to bind the glucose molecules together. The processes

that is done to create the glycogen is dehydration synthesis.Dehydration synthesis is achemical reaction that will form water when it builds a larger molecule out of smaller subunits.When the cells are creating the new glycogen it requires the hydrogen atom to be removed fromone of the glucose molecules and a hydroxyl removed from another. Next a bond is formedbetween one of the carbon atoms form one glucose molecule to a oxygen atom of a differentglucose molecule. A bond between the hydroxyl and the hydrogen atom is also formed. Theresult is two disaccharides and water. Below is a picture of the dehydration synthesis ofdisaccharides.

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Hydrolysisand dehydration synthesisreactions use specific enzymes. This makes the

reaction to be carefully regulated and creates a outcome that is similar each time. Every time

the body is hungry and carbohydrates are taken in the same process is used. So it uses the

breakdown reactions and the building reactions for energy usage and storage. Lipids, proteins

also use hydrolysis and dehydration synthesis. Theses reactions work as a cycle also, not just

when the body is digesting. Lets say a person goes on a strict diet or fasts, and that causes the

blood glucose concentration to fall. The fall will be detected with an active negative feedback

loops which Tayler describes next. In result to the fall the body will try to maintains homeostasis

and the glycogen that the liver is storing will then be hydrolyzed to from free glucose molecules.

The blood takes in the glucose molecules and brings them to the skeletal muscles so it can be

used as energy. The adipose tissue that is also stored by dehydration synthesis reactions will

need to be hydrolyzed and release subunits into the blood.