Large Molecules In the Structure And Functioning Of Cells
Large biological molecules are found in all cells, in plant and
animals cells too. There are many different large biological molecules
such as carbohydrates, proteins, lipids, nucleic acids which are all
extremely important to the functioning and structure of living cells.
We would not be alive if any of these groups were missing. This
signifies their importance.
Carbohydrates contain three elements. Carbon (C), Hydrogen (H) and
Oxygen (O) Carbohydrates are found in three forms. Monosaccharide,
Disaccharides (both sugars), and Polysaccharides. Disaccharides and
glycosydic bonds are formed when two monosaccharide are condensed
together. One monosaccharide loses an H atom from carbon atom number 1
and the other loses an OH group from carbon 4 to form the bond. The
reaction, which is called a condensation reaction, involves the loss
of water (H2O) and the formation of a 1, 4-glycosidic bond. Depending
on the monosaccharide used, this can be an ï¡-1, 4-glycosidic bond or a
ï¢-1, 4-glycosidic bond. The reverse of this reaction, the formation of
two monosaccharide from one disaccharide, is called a hydrolysis
reaction and requires one water molecule to supply the H and OH to the
sugars formed. Examples of Disaccharides are sucrose (glucose +
fructose), Lactose (glucose + galactose), Maltose (glucose + glucose)
Polysaccharides such as starch are made up of two polymers: amylase
Lipidsare made up of the elements carbon, hydrogen and oxygen but in
different proportions to carbohydrates. The most common type of lipid
is the triglyceride. Fats and oils are very similar in structure
(triglycerides). At room temperature, fats are solids and oils are
liquids. Triglycerides are made up of 3 fatty acid chains attached to
a glycerol molecule.
In the fatty acid chains the carbon atoms may have single bonds
between them making the lipid saturated. These are usually solid at
room temperature and are called fats. If one or more bonds between the
carbon atoms are double bonds, the lipid is unsaturated. These are
usually liquid at room temperature and are called oils.
Proteins:There about 20 different amino acids that all have a similar
chemical structure but behave in very different ways because they have
different side groups. Hence, stringing them together in different
combinations produces very different proteins.
Each amino acid has an amino group (NH2) and a carboxylic acid group
(COOH). The R group is a different molecule in different amino acids
which can make them neutral, acidic, alkaline, aromatic (has a ring
structure) or sulphur-containing.
When 2 amino acids are joined together (condensation) the amino group
from one and the acid group from another form a bond, producing one
molecule of water. The...