What is the difference between monomer and monosaccharide

Monosaccharides can exist as a linear chain or as ring-shaped molecules; in aqueous solutions they are usually found in ring forms. Monosaccharides : Monosaccharides are classified based on the position of their carbonyl group and the number of carbons in the backbone.

Aldoses have a carbonyl group indicated in green at the end of the carbon chain, and ketoses have a carbonyl group in the middle of the carbon chain. Trioses, pentoses, and hexoses have three, five, and six carbon backbones, respectively. Glucose C 6 H 12 O 6 is a common monosaccharide and an important source of energy. During cellular respiration, energy is released from glucose and that energy is used to help make adenosine triphosphate ATP.

Plants synthesize glucose using carbon dioxide and water, and glucose, in turn, is used for energy requirements for the plant. Galactose a milk sugar and fructose found in fruit are other common monosaccharides. Although glucose, galactose, and fructose all have the same chemical formula C 6 H 12 O 6 , they differ structurally and stereochemically.

This makes them different molecules despite sharing the same atoms in the same proportions, and they are all isomers of one another, or isomeric monosaccharides. Glucose and galactose are aldoses, and fructose is a ketose. During this process, the hydroxyl group of one monosaccharide combines with the hydrogen of another monosaccharide, releasing a molecule of water and forming a covalent bond.

A covalent bond formed between a carbohydrate molecule and another molecule in this case, between two monosaccharides is known as a glycosidic bond.

Glycosidic bonds also called glycosidic linkages can be of the alpha or the beta type. Disaccharides : Sucrose is formed when a monomer of glucose and a monomer of fructose are joined in a dehydration reaction to form a glycosidic bond.

In the process, a water molecule is lost. By convention, the carbon atoms in a monosaccharide are numbered from the terminal carbon closest to the carbonyl group.

In sucrose, a glycosidic linkage is formed between carbon 1 in glucose and carbon 2 in fructose. Common disaccharides include lactose, maltose, and sucrose.

Lactose is a disaccharide consisting of the monomers glucose and galactose. It is found naturally in milk. Maltose, or malt sugar, is a disaccharide formed by a dehydration reaction between two glucose molecules. Her expertise lies in travel and home-decorating. Andrews graduated with a bachelor's degree in communications from the University of Houston in What Are the Four Macromolecules of Life? What Is a Hydrocarbon Chain? Defining Characteristics of Lipid Molecules.

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If a polymer is made of ten monomers, how many water molecules will be needed to break all the See all questions in Monomers and Polymers. Impact of this question views around the world. Polysaccharides are very diverse in their structure. Three of the most biologically important polysaccharides— starch , glycogen , and cellulose —are all composed of repetitive glucose units, although they differ in their structure Figure 4.

Cellulose consists of a linear chain of glucose molecules and is a common structural component of cell walls in plants and other organisms. Glycogen and starch are branched polymers; glycogen is the primary energy-storage molecule in animals and bacteria, whereas plants primarily store energy in starch.

The orientation of the glycosidic linkages in these three polymers is different as well and, as a consequence, linear and branched macromolecules have different properties. Modified glucose molecules can be fundamental components of other structural polysaccharides.

Examples of these types of structural polysaccharides are N-acetyl glucosamine NAG and N-acetyl muramic acid NAM found in bacterial cell wall peptidoglycan. Polymers of NAG form chitin , which is found in fungal cell walls and in the exoskeleton of insects.

Figure 4. Starch, glycogen, and cellulose are three of the most important polysaccharides. In the top row, hexagons represent individual glucose molecules. Micrographs bottom row show wheat starch granules stained with iodine left , glycogen granules G inside the cell of a cyanobacterium middle , and bacterial cellulose fibers right. Chitin is a structural polymer found in cell walls of fungi and exoskeletons of some animals.

Skip to main content. Microbial Biochemistry. Search for:. Carbohydrates Learning Objectives Give examples of monosaccharides and polysaccharides Describe the function of monosaccharides and polysaccharides within a cell. Think about It Why do monosaccharides form ring structures?

Figure 3.