Carbohydrates - SS1 Biology Lesson Note

Carbohydrates are one of the three main macronutrients, along with proteins and fats. They are a major source of energy for the body and play a crucial role in various bodily functions. Carbohydrates are made up of carbon, hydrogen, and oxygen atoms.

Carbohydrates are the body's preferred source of energy, especially for the brain and muscles. When we consume carbohydrates, they are broken down into glucose, which is then transported through the bloodstream to provide energy to cells. Excess glucose can be stored in the liver and muscles as glycogen for later use.

Carbohydrates can be classified into three main types based on their chemical structure and complexity:

1.     Monosaccharides: Monosaccharides are the simplest form of carbohydrates and cannot be further broken down into smaller units. They consist of a single sugar molecule. Examples of monosaccharides include glucose, fructose, and galactose. Glucose is the primary source of energy for the body.

2.     Disaccharides: Disaccharides are formed when two monosaccharide molecules combine through a process called condensation. Common disaccharides include:

§  Sucrose: Composed of glucose and fructose, sucrose is commonly known as table sugar. It is naturally found in sugarcane, sugar beets, and fruits.

§  Lactose: Lactose is made up of glucose and galactose and is commonly found in milk and dairy products.

§  Maltose: Maltose is formed by the combination of two glucose molecules. It is present in germinating grains and malted foods.

1.     Polysaccharides: Polysaccharides are complex carbohydrates composed of long chains of monosaccharide units. They can be further classified into two types:

§  Starch: Starch is the storage form of glucose in plants. It is found in foods such as grains (wheat, rice, corn), potatoes, and legumes. Starch is broken down into glucose during digestion and serves as a source of energy.

§  Fiber: Fiber, also known as dietary fiber, refers to a group of polysaccharides that cannot be digested by the human body. It is found in plant-based foods such as fruits, vegetables, whole grains, and legumes. Fiber adds bulk to the diet, aids in digestion, promotes satiety, and supports a healthy digestive system.

Figure 69 image from britannica.com