Cellulose vs Glycogen vs Glucose
Glucose, cellulose, and glycogen are categorized as carbohydrates. Carbohydrates are the most abundant type of organic molecules on earth. They are the source of chemical energy for living organisms. Not only this, they serve as important constituents of tissues. Carbohydrate can be again categorized into three as monosaccharide, disaccharides and polysaccharides. Monosaccharides are the simplest carbohydrate type. Disaccharide is the combination of two monosaccharides. When ten or higher number of monosaccharides is joined by glycosidic bonds, they are known as polysaccharides.
Glucose is a monosaccharide that contains six carbon atoms and an aldehyde group. Therefore, it is a hexose and an aldose. It has four hydroxyl groups and has the following structure.
Though it is shown as a linear structure, glucose can be present as a cyclic structure too. In fact, in a solution, majority of the molecules are in the cyclic structure. When a cyclic structure is forming, the -OH on carbon 5 is converted into the ether linkage, to close the ring with carbon 1. This forms a six member ring structure. The ring is also called a hemiacetal ring, due to the presence of carbon that has both an ether oxygen and an alcohol group. Because of the free aldehyde group, glucose can be reduced. Thus, it is called a reducing sugar. Further, glucose is also known as dextrose because, it rotates plane polarized light to the right.
When there is sunlight, in plant chloroplasts, glucose is synthesized using water and carbon dioxide. This glucose is stored and used as a source for energy. Animals and human obtain glucose from plant sources. Glucose level in human blood is regulated by homeostasis mechanism. Insulin and glucagon hormones are involved in the mechanism. When there is high glucose level in blood, it is called a diabetic condition. The measurement of blood sugar level measures the glucose level in blood. There are various means to measure the blood glucose level.
Glycogen is a glucose polymer, which is analogous to starch, but this is more branched and complex than starch. Glycogen is the main storage polysaccharide in our bodies and also in some micro organisms. In our bodies, it is synthesized and stored mainly in the liver. When high level of glucose is in our blood, those glucose molecules are converted to glycogen, and this process is stimulated by glycogen hormone. When the blood glucose level is lower than the standard value, glycogen is converted back to glucose with the help of insulin. This glycogen, glucose homeostasis is important in our bodies. If there is an abnormality in maintaining glycogen levels, diabetes, hypoglycemia can be resulted. Glycogen has a similar structure to amylopectine. Glycogen polymer has α(1→4)-glycosidic bonds. At the branching points, 1,6- glycosdic bonds are formed.
Cellulose is a polysaccharide which is made out of glucose. Glucose units are bonded together by β(1→4) glycosidic bonds. Cellulose doesn’t branch, but due to the hydrogen bonds between molecules it can form very rigid fibers. Cellulose is abundant in the cell walls of green plants and algae. Therefore, this is the most common carbohydrate on the earth. Cellulose is used to make paper and other useful derivatives. It is further used to produce bio fuels.
What is the difference between Cellulose and Glucose and Glycogen?
• Glucose is a monosaccharide but glycogen and cellulose are polysaccharides. In cellulose β(1→4) glycosidic bonds are present between glucose and in glycogen α(1→4)-glycosidic bonds present.
• Cellulose is a straight chain polymer whereas glycogen is branched. Glucose is a monomer.
• Of the three, glucose has a very small molecular weight.
• Glycogen is a storage form and cellulose is a constituent in cells. Glucose is the energy producing form within cells.