MonosaccharidesMonosaccharides

• (CH2O)n

• If n=3, triose (glyceraldehyde)• If n=5, pentose (ribose)• If n=6, hexose (glucose, galactose)• Monosaccharides are used for

– Energy– Building blocks

Can you…

Draw on the diagram where a glycosidic bond will form and complete the diagram to show the disaccharide that will be produced.

Can you…

Draw on the diagram where a glycosidic bond will form and complete the diagram to show the disaccharide that will be produced.

Examples of DisaccharidesExamples of Disaccharides

Maltose

Formed from 2 glucose molecules, formed in germinating seeds from the breakdown of starch, providing energy

Sucrose

Formed from 1 glucose and 1 fructose molecule and is the form in which carbohydrates are transported in the phloem in plants

Lactose

Formed from 1 glucose and 1 galactose molecule, it is an energy source found in the milk of nearly all mammals

PolysaccharidesPolysaccharidesCarbohydrates which are made from many linked monosaccharide

monomers form long chain-like molecules

called polymers.

- made from glucose

monomers

polysaccharides cellulose

glycogen

starch

Starch

Made of α glucose molecules linked by glycosidic bonds.

Used as an energy store in plants.

Not soluble.

Forms solid grains inside plant cells (often inside chloroplasts).

The chains coil up into a basic spiral shape making the molecules compact.

Hydrogen bonds hold the polysaccharide chain in the compact spiral shape.

GlycogenThis is the storage polysaccharide in animals(equivalent to starch in plants).

Found in liver and muscle cells where a store of energy is needed.

Many fungi also store glycogen.

Similar in structure to starch - but more branched.

Forms tiny granules inside cells which are usually associated with smooth endoplasmic reticulum.

Each glycogen molecule contains a few 1000 glucose units.

Cellulose

Most abundant organic molecule.

It is very slow to decompose.

20-40% of the plant cell wall.

Made of β glucose units.

Every other β glucose is rotated through 180° - this makes the chains straight, not coiled.

Hydrogen bonding between monosaccharide molecules in the chain gives strength.

Hydrogen bonding between cellulose molecules cause bundles called microfibrils to develop. These are held together in fibres.

A cell wall will have several layers of fibres running in different directions - gives great strength almost equal to steel.

Provides support in plants and stops plant cells bursting.

Freely permeable to water and solutes.

Can you…

Draw on the diagram where a glycosidic bond will form and complete the diagram to show the disaccharide that will be produced.

Hydrolysis