Abiogenesis
See also: Origin of Life
Abiogenesis is the scientific theory as to how nonliving matter could give rise to living organisms. The theory revolves around the idea that simple polymers that can easily be formed in the primitive Earth conditions could give rise to more complex structures such as liposomes, small spherical structures made of fatty molecules. Small molecules such as bases could pass through the membrane but could not leave because once inside, they would bond to other bases, becoming to large to exit. These pseudo-life forms "reproduced" through mechanical breakage from water currents.
The bases that entered the liposome consisted of adenine, guanine, uracil, and cytosine: the components of RNA. Because trillions of the liposomes formed in the primitive Earth's pools of water, there is a high chance that self copying RNA began to form. In fact, scientists have been able to create self replicating RNA molecules through minimalist construction.
Liposomes grew in size when they came into contact with each other, thus they grew collectively larger in size. In addition to self replicating RNA, other forms of polymers began to arise, most notably polymers with the ability to bind to other polymers. This allowed for two liposomes to link together. The significance to this is that this is the basis for multicellular life. Because the enzymes formed by RNA become denatured at high temperatures, liposomes can not exist at higher water levels where the heat is greater (due to thermal vents). Thus liposomes bound together had the advantage of being able to use their higher mass to stay in optimal temperatures; this is one of the earliest examples of evolution. This process has been observed in yeast. http://www.bti.umn.edu/gateway/011912travisano_article.html
Another important aspect to abiogenesis is the endosymbiotic theory. Endo meaning inside, and symbiotic meaning coexisting life. This theory is widely agreed upon by biologists primarily due to the difference in genetic material between mitochondria, chloroplasts, and the cells they inhabit. The theory states that mitochondria and chloroplasts were once free living bacteria like organisms that were engulfed through phagocytosis by large liposomes. Thus, they began to provide and generate energy for the liposome while being given protection from mechanical forces. We can observe the foreign behavior of mitochondria and chloroplasts today. Mitochondria and chloroplasts reproduce independently of the cells they exist in and reproduce through binary fission rather than mitosis. Additionally, they do not follow Mendellian genetics. This unique trait of mitochondria is used today in genealogy and forensics to track down people through their mothers, as only the egg provides mitochondria for the zygote.
In summation, abiogenesis is a widely accepted theory that provides the foundation for the theory of evolution. Multiple experiments have been carried out proving this theory, most notably the Miller-Urey experiment (although the experiment was later discredited, researchers created a more accurate experiment that yielded the same results).
Historical Meanings
Abiogenesis may also refer to spontaneous generation, an archaic theory that stated that life could appear spontaneously under particular conditions. For example, pieces of cheese and bread wrapped in rags and left in dark areas were thought to produce mice, because after several weeks, mice appeared in the food. The same reasoning was applied to the appearance of maggots on decaying meat. [1]. This theory was finally put to rest by experiments by Louis Pasteur.
Biblical Origin of Life
See also: Origin of Life
The most famous example of abiogenesis begins in Genesis 1:20, when God created life:
And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven. Genesis 1:20 (KJV)
