Structure and Function of Carbohydrates

Structure and Function of Carbohydrates

What are carbohydrates? Carbohydrates are divided into many categories. Distinguish between monosaccharides, disaccharides, and polysaccharides through learning about carbohydrate structure and function.

We will explore the structure and function of Carbohydrates with examples in this post.

What are Carbohydrates?

People are acquainted with carbs since they are a kind of macromolecule found in a wide variety of foods. To lose weight, some individuals use a low-carbohydrate diet. As a counter-argument, athletes are known to “carb-load” before important competitions to maximise their performance.

Carbohydrates are a vital element of our diet, and whole grains, fruits, and vegetables are excellent sources. For instance, carbs provide the body with energy, glucose, a basic sugar present in starch and other common meals. Throughout the animal and plant kingdoms, carbohydrates perform several functions.

Carbohydrates have the stoichiometric formula (CH2O)n, where n is the number of carbons in a molecule. Carbohydrate molecules have a carbon-to-hydrogen-to-oxygen ratio of 1:2:1. Carbon (“carbo”) and water are the components of this formula, which explains how the name “carbohydrate” came to be (thus, “hydrate”). Therefore, the three types of carbohydrates are composed of monosaccharides, disaccharides, and polysaccharides.


Monosaccharides (mono = “one”; saccharine Means “sweet”) are simple sugars such as glucose. Monosaccharides typically include three to seven carbon atoms. Most monosaccharide names finish with the suffix –one.

As opposed to a ketose, which comprises, therefore, most, and however a single ketone atom, an aldose contains an aldehyde group (the structural-functional group R-CHO), whereas a ketose has two. To differentiate them, depending on the number of carbons in the sugar, they are also known as trioses, pentoses, and hexoses (six carbons). 

As you can see in Figure 1, the monosaccharides are relatively simple to understand.

  • Monosaccharides are classified according to the location of the carbonyl group and the number of carbons in the backbone. 
  • When it comes to aldoses, a carbonyl group (shown in green) is at the very end of the carbon chain; however, it’s in the centre when it comes to ketoses. 
  • Trioses, pentoses, and hexoses all have three, five, or six carbon backbones, respectively.

In aqueous solutions, monosaccharides are found as rings rather than as a linear chain (Figure 2). 

  • There are two methods to organise glucose’s hydroxyl (OH) group’s ring conformation around the anomeric carbon (carbon one that becomes asymmetric in the process of ring formation). 
  • Alpha () position means the hydroxyl group is below C1 in the sugar; beta () position means it is above the plane; both positions are used interchangeably.


The disaccharides (di– = “two”) form after the dehydration of two monosaccharides (also known as a condensation reaction or dehydration synthesis). Monosaccharides come in a variety of types. During this reaction, the hydroxyl group of one monosaccharide combines with the hydrogen of another, releasing a water molecule and forming a covalent connection in the process. 

In this example, a glycosidic bond is a covalent link between two carbohydrate molecules (Figure 4). You will find two kinds of glycosidic connections: alpha and beta.

There are several different kinds of disaccharides (Figure 5). 

  • To make lactose, you’ll need glucose and galactose monomers, which combine to form a disaccharide. 
  • It’s naturally found in milk. 
  • Maltose, sometimes called malt sugar, is a disaccharide formed when two glucose molecules are dehydrated. 
  • Table sugar, often known as sucrose, is a common disaccharide of monomers of glucose and fructose.


There are numerous monosaccharides in a polysaccharide (poly– = “many”). The chains are linked together by glycosidic bonds. Branching or unbranching of the chain is possible; the chain may include multiple monosaccharide types. 

The molecular weight may range from 50,000 Daltons to more than 100,000 Daltons, depending on how many monomers are bonded together. Starch, glycogen, cellulose, and chitin are examples of polysaccharides.

There are 1-4 or 1-6 glycosidic connections connecting glucose monomers to make starch. The residues’ carbon numbers are denoted by the digits 1-4 and 1-6, respectively. Amylose is a starch made from unbranched glucose monomers (only 1-4 connections). Amylopectin is a branched polysaccharide (1-6 linkages at the branch sites. It may be seen in Figure 6.

  • Glycogen, which is composed of glucose monomers, is the body’s main source of glucose storage. 
  • It’s the animal version of starch, and it’s a highly branched molecule that’s mostly found in the liver and muscle cells of animals. 
  • When blood glucose levels drop, a process known as glycogenolysis releases glucose from stored glycogen.
  • Cellulose is the most prevalent natural biopolymer. Cell walls of plants are mostly made of cellulose, which provides structural support to the cell. 
  • Additionally, natural resources such as wood and paper, both cellulosic materials, abound. 

Cellulose is made up of glucose monomers connected by 1-4 glycosidic linkages (Figure 7).

It is demonstrated in Figure 7 that every other glucose monomer in the cellulose chain has been flipped over, and the monomers are packed tightly into extended long chains. This gives cellulose its rigidity and high tensile strength, which are essential for plant cells to function correctly.

  • The digestive enzymes in humans cannot break down the 1-4 linkage; however, herbivores like cows, koalas, buffaloes, and horses can digest cellulose-rich plant materials. 
  • These animals can utilise it as a food source. They have a particular bacterium in their stomach. 
  • Certain bacteria and protists that dwell in the rumen (a section of a herbivore’s digestive system) release the enzyme cellulase, which aids in the digestion of plant matter.

Carbohydrates Have a Variety of Functions

Carbohydrates have a wide range of functions in animals, including energy production. Examples include arthropods (insects, crustaceans, and other arthropods) covered in an exoskeleton protecting their internal organs.

This exoskeleton is composed of the biological macromolecule chitin, which contains polysaccharide-containing nitrogen and polysaccharides. It is made up of repeated units of N-acetyl-d-glucosamine, a modified sugar, and other components. Additionally, chitin is an essential component of fungal cell walls; fungi are neither animals nor plants and are classified as members of the Eukarya kingdom.


I’m hoping for the best. Monosaccharide You have gained an understanding of carbohydrates, their structure, and categorisation, which includes monosaccharides, disaccharides, and polysaccharides, among other things. 

In addition, we learned about the chemical formula for sugar. We also learnt about several types of carbohydrates, such as monosaccharides, disaccharides, and polysaccharides, and a variety of other fascinating subjects relating to the structure and function of carbohydrates.

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