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5 Billion Years Ago
The solar system was a swirling mass of gas and dust. Materials were then pulled together by gravity, forming the sun. The remaining gas and dust still circled the sun. Planets were formed by collisions of space debis. -
4.6 billion Years Ago
The earth began to form. It grew larger as gravity began to pull in more debris. Collisions between earth and space debris released thermal energy, smoothing out the earth's surface. -
A Billion Years Ago
During this time, the ozone (O3) was formed. The ozone was created when oxygen reached the upper part of the atmosphere where it was bombarded with sunlight. this broke apart the oxygen bonds and created O3. The ozone layer helped to protect organisms from harmful UV rays so that the could live on earth. -
4 Billion Years Ago
The earth continued to increase in size, and organic molecules such as rock began to accumulate. Scientists estimate that this is the estimated age of the earth. -
4 Billion Years Ago
Archeabacteria, the first cellular living thing on earth, began to appear. -
3.5 Billion Years Ago
Lynbaya cells began to grow in colonies called stromatolites. In this time, cyanobacteria began to form. -
3 Billion Years Ago
During this period of time, life forms started to become photosynthetic. -
2.2 Billion Years Ago
During this time period, oxygen, as a byproduct of photosynthesis, was damaging a great number of the early unicellular organisms. Oxygen destroyed the coenzyme that was essential to the cells function, killing the organisms. In some organisms, oxygen was bonded to the compounds, this bonding prevented the oxygen from doing damage to the cell. This bonding of oxygen was the first step of aerobic respiration. -
2 Billion Years Ago
During this time periond, oxygen levels reached today's levels. This happened by the oxygen having reached the upper part of the atmosphere where it was hit by sunlight. Some of the wavelangths of sunlight split into O2 and formed highly reactive single oxygen atoms, O. O2 and O reacted with eachother, forming the ozone, O3. -
1.5 Billion Years Ago
A type of small aerobic prokaryote was engulfed by and began to live and reproduce inside a larger anaerobic prokaryote. This lead to the development of eukaryotic cells . The creation of these eukaryotic cells and the process of their formation was called endosymbiosis, and eventually developed into the formation of mitochondria and chloroplasts. -
Thomas Cech
In the 1980's Cech found that a type of RNA found in some unicellular eukaryotes is able to act as a chemical catalyst or enzyme, he called this molecule a ribozyme. -
Urey and Miller
These graduate students set up an experiment based off of Oparin's theory that the elements found in the early atmosphere reacted so that the formed amino acids. Their apparatus created a variety of organic compounds including amino acids. -
RadioMetric Dating
Radiometric dating is a method of establishing the age of materials such as rocks. This is done by determining the relative proportions of particular radioactive isotypes that are present in a material such as a rock. -
Lynn Margulis
He proposed that early prokaryotic cells may have developed a mutually beneficial relationship. this developed into the theory endosymbiosis, which is when a small aerobic prokaryote was engulfed by and began to live inside of a larger anaerobic prockaryote, both benefiting from the presence of the other. -
Antony Van Leeuwenhoek
Antony Van Leeuwenhoek was the person to make and use a real microscope. He was a Dutch scientist and draper, and an inventor of the microscope in the 17th century. The first microscope was hand held and had a single lens. The way Leeuwehoek had great success is that he developed ways to have a greater lens. He would take a class ball and grind it and the polish it to eventually get a magnification of 270X. That was the best magnification of that time. -
Francesco Redi
He noticed different forms of flies and disproved spontaneous generation. He questioned this theory when he observed this, by putting meat in a jars, one was sealed and the other wasn't. When maggots were found only on the meat that wasn't sealed, Redi concluded that microorganisms do not just spontaneously appear, put are carried in the air. -
Spallanzani
. Scientists believed that since there was no logical explanation for these microorganisms and how they got there that they must be spontaneously generated. He was going to test broth to see if microorganisms in the air are really spontaneously generated. He sealed one flask and left one flask open. At the end of the experiment the sealed flask was clear while the open flask was cloudy. He proceeded to conclude that the microorganisms came from the air. -
Louis Pasteur
Louis Pasteur was a scientist that wanted to clear u all the confusion about spontaneous generation. He fixed the problems from Spallanzani’s experiment. Instead of closing the flask off he made a curved neck so that the solid particles like microorganisms could not get into the flask. This broth stayed clear for a year in this experiment. When he took one of the flasks and broke of the neck the broth got cloudy within a day. -
Sidney Fox
He researched the physical structures of the first cells, structures shuch as the microsphere and coacervates. -
Oparin
Oparin though that many organic compounds went through many reactions that eventually lead to more complex molecules. He thought that these molecule formed coacerates, or colloid aggregates. Oparin believed that the earth contained methane, ammonia, hydrogen, and water vapor. In his opinion, these were the raw materials for the evolution of life. This would eventually lead to the first forms of life
