CHAPTER 3BIOLOGICALMOLECULESBiological MoleculesBy Onjila bouprasertPrincess Sirindhorn’s College
CHEMICALS OF LIFE Photosynthesis converts light energy into the chemical energy of sugars and other organic compounds. This process consists of a series of chemical reactions that require carbon dioxide (CO2) and water (H2O) and store chemical energy in the form of sugar. Light energy from light drives the reactions. Oxygen (O2) is a byproduct of photosynthesis and is released into the atmosphere. The following equation summarizes photosynthesis:
6 CO2 + 6 H2O → 6(CH2O) + 6 O2 sugar Photosynthesis transfers electrons from water to energy-poor CO2 molecules, forming energy- rich sugar molecules.
When the plants are eaten, these carbon- containing biological molecules will become part of the animal which ate the plant.
TriglyceridesFats are formed when fatty acids become linked with glycerol.
TriglyceridesA triglyceride is a fat molecule which has three fatty acid chains Attached to its glycerol backbone.
Weight for weight,triglycerides produce twice the amount of energy of carbohydrate. They are an important store of energy. They are to store,being large,uncharge and insoluble in water. They are stored in spaces around organs like the kidneys,and in the layers under the skin.
There are many different types of steroids. They are all lipids. Their functions vary. Some common steroids are: SEX STEROIDS ANABOLIC STERIODS CHOLESTEROL
TESTING FOR LIPIDS•Grease spot test/Brown paper test
Phospholipids Phospholipids make up the plasma membrane of cells.One end of the phospholipid molecule is water-soluble or hydrophilic. The other end is water – insoluble or hydrophobic.
This allows the molecules to arrange of phospholipids.The water-insoluble end face ench other on the inside of the membrane.While the water-soluble ends face the aqueous environment inside and outside the cell.