Problem 35 How are carbohydrates classified... [FREE SOLUTION]

Chapter 11: Problem 35

How are carbohydrates classified? Explain.

Short Answer

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Short Answer: Carbohydrates are classified into three main types: monosaccharides, disaccharides, and polysaccharides. Monosaccharides are the simplest carbohydrates, consisting of single sugar units like glucose, fructose, and galactose. Disaccharides are formed when two monosaccharides join together, such as sucrose, lactose, and maltose. Polysaccharides are long chains of monosaccharides and can be further classified into homopolysaccharides (composed of a single type of monosaccharide) like starch, glycogen, and cellulose, or heteropolysaccharides (composed of different types of monosaccharide units) like chitin.

Step by step solution

1. Introduction to carbohydrates

Carbohydrates are one of the essential nutrients our body needs for energy and proper functioning. They are carbon, hydrogen, and oxygen-containing organic compounds that serve mostly as energy sources and as structural materials in living organisms.

2. Monosaccharides

Monosaccharides are the simplest carbohydrates, consisting of single sugar units. They cannot be hydrolyzed or broken down into smaller carbohydrates. Examples of monosaccharides include glucose, fructose, and galactose. These are usually classified based on the number of carbon atoms they have or their functional group (aldehyde or ketone). Glucose (C6H12O6) is the most common monosaccharide and an essential energy source for our body.

3. Disaccharides

Disaccharides are carbohydrates formed when two monosaccharides are joined together through a condensation reaction, with the elimination of one water molecule. This bond between two sugar molecules is called a glycosidic bond. Examples of disaccharides include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).

4. Polysaccharides

Polysaccharides are long chains of monosaccharides units joined together by glycosidic bonds. Polysaccharides are generally classified into two categories: homopolysaccharides and heteropolysaccharides.

4.1 Homopolysaccharides

Homopolysaccharides are composed of a single type of monosaccharide units. Examples include starch and glycogen, both of which are storage forms of glucose in plants and animals, respectively. Another example is cellulose, which is a structural component found in plant cell walls, composed entirely of glucose units linked together.

4.2 Heteropolysaccharides

Heteropolysaccharides are composed of different types of monosaccharide units. An example of heteropolysaccharide is chitin, which is found in the exoskeletons of arthropods, including insects and crustaceans, and in the cell walls of fungi. Chitin consists of N-acetylglucosamine units linked together by glycosidic bonds.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Monosaccharides

Monosaccharides are the simplest form of carbohydrates. Imagine these as the building blocks or "units" from which more complex carbohydrates are made.

Each monosaccharide is a single sugar molecule and cannot be broken down into a simpler sugar through hydrolysis.
Common examples include glucose, fructose, and galactose.

These simple sugars are crucial because they are the primary source of energy for our bodies.
Glucose, for example, is a vital fuel, powering our cells. We often classify monosaccharides based on the number of carbon atoms they have, such as triose (3 carbons), pentose (5 carbons), and hexose (6 carbons), or by the functional group they contain, such as aldehyde or ketone.
For instance, glucose is a hexose and an aldose because it has six carbon atoms and an aldehyde group.

Disaccharides

Disaccharides are slightly more complex carbohydrates formed when two monosaccharide molecules join together.

This joining process is called a condensation reaction, and it results in the release of a molecule of water.
The bond formed between these monosaccharides is known as a glycosidic bond.

Examples of disaccharides include sucrose (table sugar), which is formed from glucose and fructose, lactose (found in milk) formed from glucose and galactose, and maltose (produced during digestion) formed from two glucose molecules.
The formation of these disaccharides involves a specific linkage depending on the position of the hydroxyl groups in the sugar units involved.

Polysaccharides

Polysaccharides are complex carbohydrates made from long chains of monosaccharide units linked by glycosidic bonds.

These chains can contain hundreds or thousands of monosaccharide units, making them vital for structure and energy storage.
Polysaccharides can be categorized into homopolysaccharides, which are made of only one type of monosaccharide, and heteropolysaccharides, which contain different monosaccharides.

Starch and glycogen are both homopolysaccharides consisting solely of glucose units; starch serves as energy storage in plants, while glycogen does the same in animals.
Cellulose is another homopolysaccharide, providing structural support in plant cell walls. On the other hand, chitin, a heteropolysaccharide, is found in the exoskeleton of insects and crustaceans and the cell walls of fungi.

Glycosidic Bond

The glycosidic bond is a crucial feature in carbohydrate chemistry, acting as the link between sugar molecules.

This covalent bond forms during a condensation reaction, where a water molecule is released.
The nature of the glycosidic bond defines the physical properties and biological functions of the resulting carbohydrate.

In disaccharides and polysaccharides, glycosidic bonds connect the monosaccharide units.
The bond can take different forms, such as alpha or beta, which alters the molecule's digestibility and structural attributes.
For instance, the glycosidic link in starch is typically an alpha linkage, allowing it to be easily digested, whereas in cellulose, it's a beta linkage, which most organisms cannot break down.

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How are carbohydrates classified? Explain.

Short Answer

Step by step solution

1. Introduction to carbohydrates

2. Monosaccharides

3. Disaccharides

4. Polysaccharides

4.1 Homopolysaccharides

4.2 Heteropolysaccharides

Key Concepts

Monosaccharides

Disaccharides

Polysaccharides

Glycosidic Bond

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