Carbohydrates contain carbon

Carbohydrates contain carbon, hydrogen and oxygen. They are small, water-soluble molecules that have a sweet taste. They divide into two groups; monosaccharides and disaccharides.
Monosaccharides are the simplest unit of carbohydrates. They refer to any type of sugar that cannot be hydrolysed to give a simpler sugar since they are already in their simplest form. There general formula is (CH20)n, where n is any number that is equal or greater than 3.
Disaccharides are made when two monosaccharides form together by the dehydration synthesis reaction resulting in a glyosidic between the two monosaccharide molecules.
Cellulose – cellulose is made up of monomers of B-glucose. It is a huge component of tough cell walls that surround plant cells and provides plant cells their rigidity. It does this by grouping the cellulose molecules together to make micro fibrils. The cellulose cell wall also prevents the cell from bursting as water enters by osmosis, it does this by exerting inward pressure that stops any inward pressure influx of water.
Glycogen – glycogen has short chins and is highly branched. It is the main carbohydrate storage product in animals, in animals it is stored as small granules mostly in muscles and liver. Its structure suits its function of storage because it is insoluble so therefore does not draw into cells by osmosis, and it is compact, so a lot of it can be stored in a small space.
Starch – starch is made up of two glucose compounds; amylose and amylopectin. The amylose is a long unbranched glucose chain this makes it more compact, however amylopectin is a polymer, this contains lots of branches so glucose molecules can be broken down quickly and can release energy for fast actions. This makes it a very suitable molecule for storing energy.
Lipids are molecules that contain hydrocarbons and form the building blocks of the structure and function of living cells.
Phospholipids – phospholipids and lipids are very similar except that one of the fatty acid molecules is replaced by a phosphate molecule in a phospholipid. These fatty acid molecules ward off water, the phosphate. The phospholipid molecule is thus made up of two parts: hydrophilic, which interacts with water but not fat, and is also made up of hydrophobic, which orientates itself away from the water but mixes willingly with fat. This structure makes it perfectly suited to make a phospholipid bilayer.