BIOMOLECULES

Carbohydrates

Carbohydrates

• Includes sugars, starches, and cellulose• Function to store energy and to provide

shape to organisms• Composed of carbon, hydrogen, and

oxygen

Carbohydrates (cont.)

• Can be divided into 3 groups based on their size:– Monosaccharides: simple

sugars like glucose, galactose and fructose

– Disaccharides: double sugars like sucrose, lactose and maltose

– Polysaccharides: chains of sugars like starch, glycogen, cellulose and chitin

Monosaccharides• Glucose - "Blood sugar" is the immediate

source of energy for cellular respiration. It is a moderately sweet sugar found in vegetables and fruit.

• Galactose - Galactose is not normally found in nature, but is mostly hydrolyzed from the disaccharide lactose, which is found in milk.

• Fructose - Fructose is also called the fruit sugar. Fructose is found in fruits, honey, and the sole sugar in bull and human semen.

Disaccharides• Lactose is the second most common double

sugar and is found in milk. It is a combination of glucose and another small sugar called galactose.

• Maltose is the third most double common sugar. It is not found in the foods that we eat. Instead, the body makes it when a person eats foods that contain starches such as potatoes and bread.

• Sucrose is the most common double sugar that people eat in common foods. It is found in fruits, potatoes, pasta, breads, cereals and other common foods.

Polysaccharides• Starch: a storage polysaccharide in plants • Glycogen: a highly branched storage

polysaccharide in animals. • Cellulose: a structural polysaccharide in plants.

Cellulose is a major component of plant cell walls.

• Chitin: a structural polysaccharide in fungi and animals. Chitin stiffens the cell walls of fungi and some algae and is an important component of the exoskeletons of insects and crustaceans.