What are the two difference between starch and glycogen?

Glycogen and Starch are two polymers of glucose that are found in the living cells. Glucose is produced by the process of photosynthesis in plants and is the simplest form of sugar.

Índice Show

Glycogen vs Starch
Comparison Table
What is Glycogen?
What is Starch?
Why is starch and glycogen different?
What is one difference between starch and glucose?
What is the difference between starch and glycogen brainly?
What is a difference between starch and glycogen quizlet?

Table of Contents

Glycogen vs Starch

The difference between glycogen and starch is that glycogen is the polymer of glucose that is the main energy component for fungi and animals whereas glucose is the polymer of glucose that is an important energy component for plants.

Glycogen is the essential storage component and the energy producer for animals and fungi. The monomer unit during the formation of glycogen is alpha glucose.

Starch is a vital component of energy production in plants. The glucose produced by the plants is converted to the insoluble storage substances like starch and fats.

Comparison Table

Parameters of comparisonGlycogenStarchDefinitionGlycogen is the polymeric carbohydrate of glucose that is the major component for animals and fungi.Starch is the complex sugar of glucose that is the major storage carbohydrate for plants.Monomer chainsGlycogen is the polymer where the monomer units form the short branched chains. It comprises of the monomer unit known as alpha glucose held by glycosidic bonds.Starch is made up of two further polymers- amylose and amylopectin where former forms the linear and coiled chains and latter forms the branched chains.Molecular Formula C24H42O21 is the molecular formula for glycogen.(C6H10O5)n is the molecular formula for starch.Occurs inGlycogen occurs in the form of small granules.Starch occurs in the form of grains.FunctionIt serves as the energy storing carbohydrate in animals.It serves as the energy storing carbohydrate in plants.

What is Glycogen?

Glycogen is the energy storage carbohydrate that is found only in animals and plants. It is the polymer of the simple sugar called alpha glucose.

It is also known as the animal starch and is found in liver cells, muscle cells, and stomach. It stores glucose to provide the body with the same when it is energy deficient.

When the body requires energy, glycogen is instantly broken down into glucose to provide the body energy that it requires. This process is known as glycogenolysis.

Some important facts about glycogen are:

It is the energy storage carbohydrate, especially for animals and fungi.
In humans, glycogen is stored as the body fat in the adipose tissues to provide energy when needed.
Access to blood sugar glucose is also stored as glycogen with the action of the pancreas to prevent diabetes mellitus.
The storage of glycogen by the muscle cells helps to keep the body ready for strenuous exercises and actions when required.

What is Starch?

Starch is the essential energy storage component in plants. It is the polymer that is of extreme importance to plants in energy storage and production.

Starch is further formed by the combination of two kinds of molecules namely amylose and amylopectin. Amylose has the monomer units attached in the linear and the coiled structure whereas Amylopectin forms the branched chains.

Starch occurs in the granules called amyloplasts in the plant cells. In plants, starch is further converted to form cellulose that helps in energy production, growth, and repair of the cells.

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Learning Objectives

To compare and contrast the structures and uses of starch, glycogen, and cellulose.

The polysaccharides are the most abundant carbohydrates in nature and serve a variety of functions, such as energy storage or as components of plant cell walls. Polysaccharides are very large polymers composed of tens to thousands of monosaccharides joined together by glycosidic linkages. The three most abundant polysaccharides are starch, glycogen, and cellulose. These three are referred to as homopolymers because each yields only one type of monosaccharide (glucose) after complete hydrolysis. Heteropolymers may contain sugar acids, amino sugars, or noncarbohydrate substances in addition to monosaccharides. Heteropolymers are common in nature (gums, pectins, and other substances) but will not be discussed further in this textbook. The polysaccharides are nonreducing carbohydrates, are not sweet tasting, and do not undergo mutarotation.

Starch

Starch is the most important source of carbohydrates in the human diet and accounts for more than 50% of our carbohydrate intake. It occurs in plants in the form of granules, and these are particularly abundant in seeds (especially the cereal grains) and tubers, where they serve as a storage form of carbohydrates. The breakdown of starch to glucose nourishes the plant during periods of reduced photosynthetic activity. We often think of potatoes as a “starchy” food, yet other plants contain a much greater percentage of starch (potatoes 15%, wheat 55%, corn 65%, and rice 75%). Commercial starch is a white powder.

Starch is a mixture of two polymers: amylose and amylopectin. Natural starches consist of about 10%–30% amylose and 70%–90% amylopectin. Amylose is a linear polysaccharide composed entirely of D-glucose units joined by the α-1,4-glycosidic linkages we saw in maltose (part (a) of Figure \(\PageIndex{1}\)). Experimental evidence indicates that amylose is not a straight chain of glucose units but instead is coiled like a spring, with six glucose monomers per turn (part (b) of Figure \(\PageIndex{1}\)). When coiled in this fashion, amylose has just enough room in its core to accommodate an iodine molecule. The characteristic blue-violet color that appears when starch is treated with iodine is due to the formation of the amylose-iodine complex. This color test is sensitive enough to detect even minute amounts of starch in solution.

Figure \(\PageIndex{1}\): Amylose. (a) Amylose is a linear chain of α-D-glucose units joined together by α-1,4-glycosidic bonds. (b) Because of hydrogen bonding, amylose acquires a spiral structure that contains six glucose units per turn.

Amylopectin is a branched-chain polysaccharide composed of glucose units linked primarily by α-1,4-glycosidic bonds but with occasional α-1,6-glycosidic bonds, which are responsible for the branching. A molecule of amylopectin may contain many thousands of glucose units with branch points occurring about every 25–30 units (Figure \(\PageIndex{2}\)). The helical structure of amylopectin is disrupted by the branching of the chain, so instead of the deep blue-violet color amylose gives with iodine, amylopectin produces a less intense reddish brown.

Figure \(\PageIndex{2}\): Representation of the Branching in Amylopectin and Glycogen. Both amylopectin and glycogen contain branch points that are linked through α-1,6-linkages. These branch points occur more often in glycogen.

Dextrins are glucose polysaccharides of intermediate size. The shine and stiffness imparted to clothing by starch are due to the presence of dextrins formed when clothing is ironed. Because of their characteristic stickiness with wetting, dextrins are used as adhesives on stamps, envelopes, and labels; as binders to hold pills and tablets together; and as pastes. Dextrins are more easily digested than starch and are therefore used extensively in the commercial preparation of infant foods.

The complete hydrolysis of starch yields, in successive stages, glucose:

starch → dextrins → maltose → glucose

In the human body, several enzymes known collectively as amylases degrade starch sequentially into usable glucose units.

Glycogen

Glycogen is the energy reserve carbohydrate of animals. Practically all mammalian cells contain some stored carbohydrates in the form of glycogen, but it is especially abundant in the liver (4%–8% by weight of tissue) and in skeletal muscle cells (0.5%–1.0%). Like starch in plants, glycogen is found as granules in liver and muscle cells. When fasting, animals draw on these glycogen reserves during the first day without food to obtain the glucose needed to maintain metabolic balance.

Glycogen is structurally quite similar to amylopectin, although glycogen is more highly branched (8–12 glucose units between branches) and the branches are shorter. When treated with iodine, glycogen gives a reddish brown color. Glycogen can be broken down into its D-glucose subunits by acid hydrolysis or by the same enzymes that catalyze the breakdown of starch. In animals, the enzyme phosphorylase catalyzes the breakdown of glycogen to phosphate esters of glucose.

About 70% of the total glycogen in the body is stored in muscle cells. Although the percentage of glycogen (by weight) is higher in the liver, the much greater mass of skeletal muscle stores a greater total amount of glycogen.

Cellulose

Cellulose, a fibrous carbohydrate found in all plants, is the structural component of plant cell walls. Because the earth is covered with vegetation, cellulose is the most abundant of all carbohydrates, accounting for over 50% of all the carbon found in the vegetable kingdom. Cotton fibrils and filter paper are almost entirely cellulose (about 95%), wood is about 50% cellulose, and the dry weight of leaves is about 10%–20% cellulose. The largest use of cellulose is in the manufacture of paper and paper products. Although the use of noncellulose synthetic fibers is increasing, rayon (made from cellulose) and cotton still account for over 70% of textile production.

Like amylose, cellulose is a linear polymer of glucose. It differs, however, in that the glucose units are joined by β-1,4-glycosidic linkages, producing a more extended structure than amylose (part (a) of Figure \(\PageIndex{3}\)). This extreme linearity allows a great deal of hydrogen bonding between OH groups on adjacent chains, causing them to pack closely into fibers (part (b) of Figure \(\PageIndex{3}\)). As a result, cellulose exhibits little interaction with water or any other solvent. Cotton and wood, for example, are completely insoluble in water and have considerable mechanical strength. Because cellulose does not have a helical structure, it does not bind to iodine to form a colored product.

Figure \(\PageIndex{3}\): Cellulose. (a) There is extensive hydrogen bonding in the structure of cellulose. (b) In this electron micrograph of the cell wall of an alga, the wall consists of successive layers of cellulose fibers in parallel arrangement.

Cellulose yields D-glucose after complete acid hydrolysis, yet humans are unable to metabolize cellulose as a source of glucose. Our digestive juices lack enzymes that can hydrolyze the β-glycosidic linkages found in cellulose, so although we can eat potatoes, we cannot eat grass. However, certain microorganisms can digest cellulose because they make the enzyme cellulase, which catalyzes the hydrolysis of cellulose. The presence of these microorganisms in the digestive tracts of herbivorous animals (such as cows, horses, and sheep) allows these animals to degrade the cellulose from plant material into glucose for energy. Termites also contain cellulase-secreting microorganisms and thus can subsist on a wood diet. This example once again demonstrates the extreme stereospecificity of biochemical processes.

Career Focus: Certified Diabetes Educator

Certified diabetes educators come from a variety of health professions, such as nursing and dietetics, and specialize in the education and treatment of patients with diabetes. A diabetes educator will work with patients to manage their diabetes. This involves teaching the patient to monitor blood sugar levels, make good food choices, develop and maintain an exercise program, and take medication, if required.

A certified diabetes educator at Naval Medical Center Portsmouth (left) and a registered dietician at the medical center (center), provide nutritional information to a diabetes patient and her mother at the Diabetes Boot Camp.

Diabetes educators also work with hospital or nursing home staff to improve the care of diabetic patients. Educators must be willing to spend time attending meetings and reading the current literature to maintain their knowledge of diabetes medications, nutrition, and blood monitoring devices so that they can pass this information to their patients.

Summary

Starch is a storage form of energy in plants. It contains two polymers composed of glucose units: amylose (linear) and amylopectin (branched). Glycogen is a storage form of energy in animals. It is a branched polymer composed of glucose units. It is more highly branched than amylopectin. Cellulose is a structural polymer of glucose units found in plants. It is a linear polymer with the glucose units linked through β-1,4-glycosidic bonds.

14.7: Polysaccharides is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by LibreTexts.

Why is starch and glycogen different?

As a general consequence, starch and glycogen differ in their water solubility. Starch consists of branched water insoluble semi-crystalline amylopectin, and the nearly linear amylose is probably interspersed within the amorphous regions of amylopectin [8,9,10]. Glycogen, in contrast, is mostly watersoluble.

What is one difference between starch and glucose?

The key difference between glucose and starch is that glucose is the simplest form of carbohydrate that can easily be absorbed by the digestive system, while starch is a complex form of carbohydrate that cannot be easily absorbed by the digestive system.

What is the difference between starch and glycogen brainly?

Starch stores energy, and glycogen provides structural support.

What is a difference between starch and glycogen quizlet?

Glycogen is stored in animals in the liver and in muscle cells, whereas starch is stored in the roots, seeds, and leaves of plants. Starch has two different forms, one unbranched (amylose) and one branched (amylopectin), whereas glycogen is a single type of a highly branched molecule.