1.2. Classification

Carbohydrates are classified based on their hydrolysis behavior:

1. Monosaccharides – Cannot be hydrolyzed further (e.g., glucose, fructose).
2. Oligosaccharides – Yield 2–10 monosaccharide units on hydrolysis (e.g., sucrose, lactose).
3. Polysaccharides – Yield many monosaccharides on hydrolysis (e.g., starch, cellulose).

Carbohydrates are classified into three main types based on how they react with water (hydrolysis):

1. Monosaccharides are the simplest form of carbohydrates. They cannot be broken down further and include sugars like glucose and fructose. Their basic structure consists of a single sugar molecule.
2. Oligosaccharides contain a small number (2-10) of monosaccharide units. When they undergo hydrolysis, they break down into these smaller sugar units. Common examples are sucrose (table sugar) and lactose (milk sugar).
3. Polysaccharides are long chains of monosaccharide units. They can contain hundreds or thousands of these sugar units linked together. Examples include starch and cellulose, which are important for energy storage and structure in plants, respectively.

Think of carbohydrates like a family tree:

• Monosaccharides are the individual family members (like glucose and fructose) who cannot be split into smaller parts.
• Oligosaccharides are small groups of family members who can be together for gatherings (like sucrose, which is made of glucose and fructose).
• Polysaccharides are the entire family reunion, with many members coming together to form complex structures (like starch or cellulose).

• Simplest sugars with the general formula Cₙ(H₂O)ₙ. • Classified as aldoses (with an aldehyde group) or ketoses (with a ketone group). Examples: • Glucose (aldohexose) • Fructose (ketohexose)

Monosaccharides, often referred to as the simplest form of sugars, have a basic chemical formula that can be represented as Cₙ(H₂O)ₙ. This means they consist of carbon (C), hydrogen (H), and oxygen (O) in a specific ratio. They are further categorized into:

1. Aldoses: These sugars have an aldehyde group (-CHO) and include glucose as a common example.
2. Ketoses: These contain a ketone group (C=O) and include fructose. Monosaccharides play a crucial role in metabolism and are key building blocks for more complex carbohydrates.

Imagine monosaccharides as the smallest building blocks of a Lego structure. Each individual Lego piece can represent a monosaccharide. Just like how a Lego piece can be a square or a rectangle (akin to aldoses and ketoses), when combined together, they can form larger structures—like houses or castles—which represent the more complex carbohydrates.

• Formed by glycosidic linkage between two monosaccharide units. Examples: • Sucrose = Glucose + Fructose • Lactose = Glucose + Galactose • Maltose = Glucose + Glucose

Disaccharides are formed when two monosaccharides are joined together through a special bond known as a glycosidic linkage. This bond is created during a process called condensation, where a molecule of water is released. Some common disaccharides include:

• Sucrose: Composed of glucose and fructose, commonly known as table sugar.
• Lactose: Made up of glucose and galactose, found in milk.
• Maltose: Formed from two glucose molecules, commonly found in malted foods.

Think of disaccharides like two friends shaking hands to form a new friendship.

• Sucrose is like a pair of friends (glucose and fructose) coming together to enjoy a meal, making it sweet like sugar.
• Lactose is like a comforting hug from family (glucose and galactose) shared over a glass of milk.
• Maltose can be imagined as two siblings (both glucose) sharing moments together, like playing with malted candies.

• Long chains of monosaccharide units. Examples: • Starch – Storage carbohydrate in plants. • Cellulose – Structural component in plant cell walls. • Glycogen – Storage carbohydrate in animals.

Polysaccharides are large molecules made up of long chains of monosaccharide units linked together. These carbohydrates serve various essential functions in living organisms. Here are some notable examples:

1. Starch: This serves as the primary energy storage form in plants. When plants make glucose through photosynthesis, they store excess glucose as starch for later use.
2. Cellulose: This is a crucial structural component of plant cell walls, giving them rigidity and strength. Our body cannot digest cellulose, but it adds important fiber to our diet.
3. Glycogen: Similar to starch, glycogen is stored in animal cells as a reserve energy source, primarily in the liver and muscles.

Imagine polysaccharides as a library:

• Starch is like all the books in the library stored neatly on the shelves, ready to provide knowledge (energy) when needed.
• Cellulose acts as the library’s strong cement walls that hold everything up, ensuring the structure stays strong and functional.
• Glycogen is like the secret storage room at the back of the library where additional resources are kept for quick access during busy times.

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