These are all examples of polysaccharides except___
options: a. starch b. glucose c. cellulose d. glycogen
The correct answer and explanation is:
Correct Answer: b. glucose
Glucose is not a polysaccharide. It is a monosaccharide, which is the simplest form of carbohydrate. Polysaccharides, in contrast, are large, complex carbohydrates made up of long chains of monosaccharide units. In most biological systems, these chains are composed of repeating glucose molecules bonded together in different ways to create diverse structures and functions.
Polysaccharides serve various roles depending on their structure. For instance:
- Starch is a polysaccharide found in plants. It acts as a storage form of energy. Starch consists of two molecules, amylose and amylopectin, both made of repeating glucose units.
- Cellulose is another polysaccharide found in plant cell walls. It provides structural support. Though it is made of glucose units, the bonds between them are different from those in starch, making cellulose rigid and indigestible to most animals.
- Glycogen is the storage form of glucose in animals, mainly stored in the liver and muscles. It has a branched structure and is rapidly broken down when the body needs glucose for energy.
Glucose, however, is a simple sugar with a single six-carbon ring structure. It is the basic building block for all the above polysaccharides. Its primary role is to provide immediate energy to cells through metabolic pathways such as glycolysis and cellular respiration.
In summary, starch, cellulose, and glycogen are all polysaccharides composed of many glucose units. Glucose stands out as the only option that is not a polysaccharide. Instead, it is the fundamental sugar from which polysaccharides are synthesized and broken down during digestion and metabolism.