Download Biological Molecules

Biological Molecules
Chapter 2
99 percent of all life is made of:




Carbon
Hydrogen
Oxygen
Nitrogen
Macromolecules
Polysacharides
 Proteins
 Nucleic acids
Polymerisation
 Repeated reactions to build up larger molecules
Carbohydrates
 Carbon, Hydrogen and Oxygen
 General formula Cx(H20) y
 Consisting of monosacharides, disacharides and
polysacharides
monosacharides





Sugars, with the general formula (CH2O)n
Named according to the number of carbon atoms
End in -ose
triose, pentose and hexose
Used mainly as an energy source (conversion
between ATP and ADP)
 Two can monosacharide molecules can join to form a
disacharide (also a sugar)
Polysacharides
 Formed by polymerisation of monosacharides
 Can form thousands of chains in length.
 Usefull polysacharides include starch, glycogen and
cellulose
 Starch (plants) and glycogen (animals) are formed so
as not to interfere with cell chemistry and osmosis.
They can be quickly broken down to glucose and used
as energy. (hydrolysis)
Cellulose
 A strong molecule forming the cell wall in plant cells
 High tensile (pulling force) strength near equal to
steel.
 Allows the cell wall to withstand high pressure when
the membrane exerts pressure.
Lipids
 Group includes Triglycerides (commonly called fats and
oils)
 Insoluble in water, though soluble in organic compounds
such as ethanol.
 Saturated and unsaturated, refers to wether or not the
maximum number of hydrogen bonds have been formed.
 Used as an excellent energy source (more calorific than
carbs) and insulation, and bouyancy in marine life.
Water solubility
 Hydrophobic ( water hating or scared of water)
 Hydrophilic (water loving)
Proteins




Used to build cell membranes
Used to build heamoglobin
Used to build enzymes
All made from the group of 20 exsisting amino acids.
Amino acids
 Several hundred amino acids can join to form a
protein.
 Ribonuclease is a very important protein
Testing for biological molecules
 Lipids – Disolve in ethanol, then add mixture to water.
A milky emulsion is a positive result.
 Reducing sugars- add Benedicts solution and heat. A
brick red colour is a positive test.
 Protein- add to buirett solution. A dark purple colour
is a positive result.
 Cellulose- Add iodine solution. A black colour is a
positive test.