Cellulose In Digestion

Table of Contents

What is Cellulose

Cellulose is a complex organic compound that occurs abundantly in nature. It is a polymeric carbohydrate molecule consisting of a linear chain having thousands of glycosidic linkages.

It consists of unbranched chains of glucose (linked D-Glucopyranose). They are straight chains linked by hydrogen bonds producing a substance that is inert and insoluble in water, in its pure form.

Modified cellulose and pure cellulose are different in their chemical compositions. They are components of the plant cell wall and have no odour or taste. It is crystalline in nature and does not dissolve water and other solvents. Termites and herbivorous animals lack the enzyme for cellulose digestion.

Digestion of Cellulose in Animals

Termites have mastigophorans (microbes) in their gut which brings about the digestion of cellulose. Herbivorous animals, on the other hand, are ruminants. They have different compartments in their stomach to carry out digestion.

The rumen is the first compartment where ingested food containing cellulose is stored temporarily and later regurgitated to chew their cud. They are able to digest cellulose because of the presence of bacteria and enzymes in the rumen where anaerobic bacterial digestion occurs. A by-product of this type of digestion releases methane which is foul-smelling and causes the destruction of the ozone layer of the Earth.

See also: Role Of Digestive Enzymes

Digestion of Cellulose in Humans

Cellulose is a fibre which is not digestible by the human digestive system. It, however, helps in the smooth functioning of the intestinal tract.

The presence of beta acetal linkages in cellulose makes it different from starch and is a deciding factor in its digestibility. Humans lack the enzyme required to break down the linkages. Furthermore, it forms a major part of the human diet from plant foods.

Fruits and vegetables contain cellulose in small amounts which are easily digestible. Fibres contain cellulose which acts as roughage, adding bulk to consumed food and helping in the smooth passage of the food efficiently and at a much faster pace. A high-fibre diet reduces the risk of colon cancer as fibre in the diet helps reduce the time the faeces stay in the colon wall.

Since it is insoluble in water it binds with other components adding bulk helping to move through the intestines by aiding bowel movements. Consuming food that does not contain cellulose over a period of time results in the bowel becoming weak leading to constipation.

These fibres aid in the growth of bacteria in the gut which feeds on sugars and fibres. They maintain the health of the gut and check for bacteria causing illness. Fibres also prevent weight gain and aid in weight loss.

Related Links: Human Digestive System

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Frequently Asked Questions


What is cellulose?

Cellulose is a polysaccharide that makes up 30% of the plant cell wall. It helps in connecting cells to form tissues and signals the cells to grow and divide.


How is cellulose important for humans?

Cellulose is a polysaccharide that makes up 30% of the plant cell wall. It helps in connecting cells to form tissues and signals the cells to grow and divide. Humans cannot digest cellulose. However, it is consumed in the diet as fibre. Fibre helps the digestive system to keep the food moving through the gut and moves the waste out of the body.


Why can’t humans digest cellulose?

Humans cannot digest cellulose because they lack the enzymes essential for breaking the beta-acetyl linkages. The undigested cellulose acts as fibre that aids in the functioning of the intestinal tract.


Where is cellulose found?

Cellulose is an important component found in the cell wall of green plants, algae and oomycetes. It is also secreted by a few bacteria to form biofilms.


Which enzyme is responsible for the breakdown of cellulose?

Cellulase is responsible for breaking down cellulose. It breaks down cellulose into monosaccharides such as beta-glucose or short polysaccharides and oligosaccharides.

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