Origin of Cells (1.5)
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Notes on Cell Basics, Stem Cells and Origins of Cells (Topic 1.1, 1.2, 1.5) |
Experiments and the Origin of Life
Two major experiments:
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Possible Stages of development to the first cell
If spontaneous generation is not possible, then how did the first cell arise? As this defies one of the fundatmental tenants of the Cell Theory (All cells come from pre-existing cells) AND we can not go back to observe early earth we must rely on historical science and the few experiments we can do. However, there are still so many issues with even the stages presented below.
1. Production of Carbon compounds such as sugars and amino acids from hypothetical early earth’s atmosphere
2. Assembly of carbon compounds into polymers
3. Formation of membranes
4. Development of a mechanism for inheritance
1. Production of Carbon compounds such as sugars and amino acids from hypothetical early earth’s atmosphere
- The Miller Urey Experiment is no longer accepted as completely accurate, as the conditions they used are no longer thought to be accurate of early earth.
- Similar experiments have been repeated using different sets of conditions with similar results producing some amino acids and sugars.
2. Assembly of carbon compounds into polymers
- Necessary energy needed to do so, plus the complicated nature of what is expected make this a difficult aspect to actually demonstrate in the first place.
3. Formation of membranes
- Phospholipids gather together to form bilayers resembling membranes
- Could possibly allow cell formation – if this is the case there is a lot more complicated chemical reactions required to create a single cell
4. Development of a mechanism for inheritance
- DNA contains the genes need to pass on traits.
- To do this, DNA needs to replicate.
- Some scientists think RNA may have served as an early form of DNA; as RNA serves as both catalyst and information storage in eukaryote cells.
- But this still does not explain the enzyme/replication problem
Endosymbiosis Theory
Endosymbiotic Theory - learn genetics (University of Utah)
Endosymbiotic Theory - theory that eukaryotic organisms evolved from prokaryotic cells through a cell engulfing another cell. Evidence includes:
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