Biological Molecules – Carbohydrates 1

Sugars, starch, cellulose

Examples of carbohydrates

Monosaccharide

Monomer form of carbohydrates

Glucose, galactose, fructose, ribose

Examples of monosaccharides

Chemical formula of monosaccharides

Usually (CH₂O)_n. For example, glucose, galactose, and fructose are C₆H₁₂O6.

Disaccharide

Dimer form of carbohydrates

Maltose, lactose, sucrose

Examples of disaccharides

Simple sugars

Monosaccharides and disaccharides

Isomers

Molecules with the same chemical formula but different arrangements of atoms. E.g., Glucose, galactose, and fructose are isomers. They all have the chemical formula C₆H₁₂O₆.

Main function of simple sugars

Most serve as the main energy source for living things. Cellular respiration converts glucose and oxygen to form carbon dioxide, water, and energy.

Polysaccharide

Polymer form of carbohydrates (also known as ‘complex carbohydrate’)

Starch, glycogen, cellulose

Examples of polysaccharides. All three are formed from glucose.

Main function of starch

Energy storage in plants

Main function of glycogen

Short-to-medium-term energy storage in animals and fungi

Main function of cellulose

Makes up the cell walls in plants

Glycosidic bond

Bond formed between monomers of carbohydrates to produce dimers or polymers.

Polysaccharide (carbohydrate)

Polysaccharide (carbohydrate)