Endosymbiosis Theory and Abiogenesis Mr. Pontifis NGC 2014-2015

Endosymbiotic Theory Theory that explains the origin of mitochondria and chloroplasts and their double membranes. Can also explain the rise of cells and their organelles. Symbiosis: occurs when two different species benefit from living together Large host cell ingested a bacterial cell to benefit from one another

The Evidence Mitochondria and chloroplasts both contain their own dNA Their dNA is different than the dNA of the cells they are found in Their genomes resemble bacterial genomes(single/circular) Both organelles can only arise from preexisting ones by dividing themselves Contain their own protein synthesizing machinery Antibiotics that can block bacterial protein synthesis can also block protein synthesis in mitochondria and chloroplasts

Abiogenesis Theory Theory that attempts to explain the origin of life Scientist suggest that many yrs ago gases in the atmosphere had the ability to react upon being struck by lightning or other sources of energy Gases would assemble into organic compounds which would further assemble into more increasingly complex molecules such as proteins These proteins ultimately developed into living cells

The Experiment Miller-Urey: two scientists that attempted to replicate the conditions for the Abiogenesis theory Water was set to boil on a flask, the vapor would pass through a condenser and into a flask containing Ammonia, Methane, and Hydrogen (Atmosphere) Resulting mixture was subject to a 50K bolt spark The resulting tar like substance was then analyzed Amino acids where found (building blocks of life), as well as carbs

Miller-Urey Experiment

Problems With the Experiment It is difficult to create the same conditions that earth experienced many yrs ago Oxygen in the atmosphere could have prevented some of the reactions from forming organic compounds AA’s were formed but in the wrong confirmations (there are L-AA’s as well as D-AA’s) Left form AA’s are common in living things Coordination of many proteins in correct order is almost impossible to create a cell Too many probabilities

L-AA’s and D-AA’s L-form is the most predominant in life forms (left handed)