T H E   G R E E N H O U S E

Chemicals of Life
 &nbsp- Water
 &nbsp- Lipids
 &nbsp- Carbohydrates

Carbohydrates



Carbohydrates are made of only :

Carbon

Hydrogen

Oxygen

Their main role is to be an easy accessable source of energy. They are grouped according to their size and complexity, and include :

Monosaccharides - Least Complex
Disaccharides
Polysaccharides - Most Complex
Monosaccharides

"mono" means one, so it bascially means 1 sugar. Its formula is shown below, and "n" is the number of carbon atoms in this molecule.

(CH2O)n


The most common monosac. is called the hextose sugar, and it has 6 carbon atoms. Glucose is a hextose sugar. The shape of the hextose sugar is very important, and can be related to the other types of carbohydates as well.

Features - A ring structure made of 5 carbon, and 1 oxygen atom.
These are branches off the main structure. Branches of H, OH(hydroxyl), and 1 CH2OH(alcohol).
Its carbon atoms must be numbered 1-6 in a clockwise direction, starting at the extreme right

There are some varients of hextose sugars, that aren’t glucose. They differ only in that some of the branches have different elements at their ends. For example, fructose is the same as glucose, except that its CH2OH is swapped with the H in position 1. These different forms are called isomers – a different positioning of atoms in a molecule.

Examples of monosaccarides are : Glucose & Fructose & Galactose.
Monosaccarides are soluble, sweet and form crystals.
Disaccarides are built up from monosaccarides.

Disaccarides

This is 2 monosaccarides joined together. Because "di" means 2. The interesting thing(and the thing we get examined on) is the process where they join to form a disaccaride. The formula for a disaccaride is:

CnH2nOn-1


When the 2 monosaccarides join, water is released, and a glycosidic link formed between the two(a covalent bond). This loose of water is called condensation.

Maltose - the combination of 2 glucose molecules.
Sucrose - the combination of glucose and fructose. Very common in plants. Found in sweets.
Lactose - the combination of glucose and galactose. It is the sugar found in milk.

The reverse process, where disaccarides split, to form 2 monosaccarides is called hydolysis, and water is needed to be added for this to occur.

Polysaccarides
These are bascially long strings of monosaccarides. They are insoluble in water, do not taste sweet and connot be crystallised. These long chains of monosaccarides can be folded, branched and be in different patterns/structures. This gives them the ability to be compact - making them easy to store - because they are too big to diffuse out of a cell. Monosaccarides break off the chain by hydrolysis to be used as energy.
Starch, glycogen & cellulose are all polysaccarides.

Starch

It is found in plants, and consists of two sorts of molecules – amylose and amylopectin. It is made up of a long chain of glucose units, and the chain is coiled in a helix pattern.


Home     The Creators
Chemicals of Life     CellularRespiration     Photosynthesis     Transpiration     Human Respiration     Human Circulation
    Human Digestion     Human Excretion     Biology Links
Thinkquest Team 22016
Andrew Griffiths
Tim Sindle
Ben Harper