Carbohydrates Summary Notes

Biological Molecules: Carbohydrates

Carbohydrates>

A group of molecules containing C, H and O.

For every C atom there are 2H atoms and an O atom.

They act as:

A source of energy, ie. glucose

A store of energy, ie. starch and glycogen

Structural units, ie. cellulose and chitin 

Some carbohydrates are part of other molecules such as nucleic acids and glycolipids.

There are three main groups of carbohydrates: monosaccharides, disaccharides and polysaccharides. 

Monosaccharides>

The simplest carbohydrates.

Particularly important in living things as a source of energy. 

Suited as an energy store because of the large numbers of hydrogen bonds. 

Soluble in water and insoluble in non-polar solvents.

POLAR=WHEN THE CHARGE IS NOT EVENLY DISTRIBUTED ACROSS THE PARTICLE.

Disaccharides>

2 Monomers, (monosaccharides), bond together to form disaccharides. 

Sweet and soluble. 

Maltose, sucrose and lactose are typical examples.

When they join, a condensation reaction occurs to form a glycosidic bond. Two hydroxyl (OH) groups line up next to each other, from which a water molecule is removed, leaving an oxygen atom acting as a link between the monosaccharide units.

Disaccharides are broken into their monomers by the addition of water, a hydrolysis reaction.

Polysaccharides>

Polymers made from many monosaccharides.

3 important examples include: starch, glycogen and cellulose. 

Are polymers, high molecular weight. 

Diversity of structure.

Branched or linear chains. 

One or more monosaccharide type.

Major importance to plants. 

Minor roles in animals. 

Hetero/homopolysaccharides.

Glycosidic bonds can form when the 'reducing group' of one monosaccharide is joined by a condensation reaction. 

When you polymerise alpha glucose you produce an alpha helix. 

Due to H bonding, the polymer of alpha glucose spontaneously folds into an alpha helix. 

The helix structure allows a lot of glucose to be stored in a small space, highly compact structure. 

Beta glucose is linear.

Credits to http://andrewpover.co.uk/biology/ocr-as-biology-amylose-amylopectin-cellulose-and-glycogen-comparison-table/

ADDITIONAL NOTES