Disaccharides are which of the following

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. Common disaccharides include maltose, lactose, and sucrose. Think about It What are the most biologically important polysaccharides and why are they important? Key Concepts and Summary Carbohydrates , the most abundant biomolecules on earth, are widely used by organisms for structural and energy-storage purposes.

Carbohydrates include individual sugar molecules monosaccharides as well as two or more molecules chemically linked by glycosidic bonds. Monosaccharides are classified based on the number of carbons the molecule as trioses 3 C , tetroses 4 C , pentoses 5 C , and hexoses 6 C.

They are the building blocks for the synthesis of polymers or complex carbohydrates. Disaccharides such as sucrose, lactose, and maltose are molecules composed of two monosaccharides linked together by a glycosidic bond. Polysaccharides , or glycans , are polymers composed of hundreds of monosaccharide monomers linked together by glycosidic bonds. The energy-storage polymers starch and glycogen are examples of polysaccharides and are all composed of branched chains of glucose molecules.

The polysaccharide cellulose is a common structural component of the cell walls of organisms. Other structural polysaccharides, such as N-acetyl glucosamine NAG and N-acetyl muramic acid NAM , incorporate modified glucose molecules and are used in the construction of peptidoglycan or chitin.

Multiple Choice By definition, carbohydrates contain which elements? Carbohydrates contain carbon, hydrogen, and oxygen. It is a product of starch digestions and may be purified from barley and other grains. It has the formula C 12 H 22 O 11 and is an isomer of sucrose. Its primary use is to treat constipation. It is a natural alpha-linked disaccharide with extremely high water retention properties.

In nature, it helps plants and animals reduce long periods without water. Here's a quick summary of the subunits of common disaccharides and how they are linked to each other.

There are many other disaccharides, although they are not as common, including isomaltose 2 glucose monomers , turanose a glucose and a fructose monomer , melibiose a galactose and a glucose monomer , xylobiose two xylopyranose monomers , sophorose 2 glucose monomers , and mannobiose 2 mannose monomers.

Note multiple disaccharides are possible when monosaccharides bond to each other, since a glycosidic bond can form between any hydroxyl group on the component sugars. For example, two glucose molecules can join to form maltose, trehalose, or cellobiose.

Even though these disaccharides are made from the same component sugars, they are distinct molecules with different chemical and physical properties from each other. Disaccharides are used as energy carriers and to efficiently transport monosaccharides. Specific examples of uses include:. Treepongkaruna, S. Pakdaman, M. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance.

Select basic ads. Create a personalised ads profile. People who are lactose intolerant cannot digest or break down lactose.

This becomes food for gas-producing gut flora. This could lead to gastrointestinal disturbance and flatulence. Lactose can be converted to lactic acid. Microorganisms, such as Lactobacilli , can convert lactose to lactic acid, which is used in the food industry, e. Thus, it may also be considered as the structural unit of glycogen and starch.

Maltose is digested or broken down into its monosaccharide units through hydrolysis with the help of the enzyme, maltase. The bond that joins the two glucose units is broken, converting maltose to two glucose units. Maltose is commercially used as a sweetener, a nutrient in infant feeding, and in bacteriological culture media. It is also used in pastries. It makes bread dough rise when carbon dioxide is produced and released during the conversion of starch into maltose by reacting the starch with enzymes.

Other examples of disaccharides are lactulose, chitobiose, kojibiose, nigerose, isomaltose, sophorose, laminaribiose, gentiobiose, turanose, maltulose, trehalose, palatinose, gentiobiulose, mannobiose, melibiose, melibiulose, rutinose, rutinulose, and xylobiose.

Dietary disaccharides, just as the other carbohydrates, are a source of energy. Disaccharides are consumed and digested so as to obtain monosaccharides that are important metabolites for ATP synthesis. ATPs are chemical energy biologically synthesized through aerobic and anaerobic respiration.

And one of the sources of glucose is a disaccharide-containing diet. Sucrose, the common table sugar, is used commonly as a sweetener. It is used in beverages and food preparation, such as cake and cookies. When consumed, the enzyme invertase in the small intestine cleaves sucrose into glucose and fructose. Too much fructose, though, could lead to malabsorption in the small intestine. When this happens, unabsorbed fructose transported to the large intestine could be used in fermentation by the colonic flora.

This could lead to gastrointestinal pain, diarrhea , flatulence, or bloating. Too much glucose could also be a health hazard. Excessive consumption of sugar could lead to diabetes , obesity, tooth decay, and cardiovascular diseases.

Lactose, a disaccharide found in breast milk, is used as a nutrient source for infants. Maltose may be used as a sweetener although it is much less sweet than sucrose. Vascular plants form disaccharides, especially sucrose, as a nutrient to be transported to various parts of the plant via the phloem tissues.

Sugarcane, most especially, is harvested to make commercialized sugar. Try to answer the quiz below to check what you have learned so far about disaccharides. Apart from vitamins, the human body also requires high energy sources such as carbohydrates and fats. If you want an overview of the different carbohydrates and fats the body needs, read this tutorial Read More. The body is comprised of different elements with hydrogen, oxygen, carbon, and nitrogen as the major four.

This tutorial will help you understand the chemical composition of the body. This will come in handy when considering the various interactions between cells and structures.