Antibiotics are medicines used to treat infections or diseases caused by bacteria (e.g. respiratory tract infections such as pneumonia and whooping cough). Antibiotics are used for a range of other infections caused by bacteria, including urinary tract infections, skin infections and infected wounds.
Miller- Urey experiment suggested the primitive earth's atmosphere and proved the chemical origin of life. A primitive earth's atmosphere was simulated in an experimental set up with methane, ammonia, hydrogen and water. Electric sparks were created similar to lightning and the water vapour generated was allowed to cool and condense. This sample, when analysed after purification was found to contain amino acids. Thus, proving the chemical origin of life.
Though the experiment proved the synthesis of amino acids which are the building blocks of proteins, it failed to explain the assembly of proteins from the amino acids. The information for the coding these proteins in presence of the DNA or the RNA was also not explained. Also, the gases used in the experiment were not abundant in the primitive earth's atmosphere. Thus, scientists now believe that Miller-Urey experiment was not an accuarate depicction of the conditions on the early earth.
The arrangement of phospholipid molecules makes up the lipid bilayer. The phospholipids of a cell membrane are arranged in a double layer called the lipid bilayer. The hydrophilic phosphate heads are always arranged so that they are near water.