- 2903 - PREHISTORIC EARTH - how did life get started? Four billion years ago, Earth was covered in a watery sludge swarming with primordial molecules, gases, and minerals, nothing that biologists would recognize as alive. Out of that prebiotic stew emerged the first critical building blocks, proteins, sugars, amino acids, cell walls, that would combine over the next billion years to form the first specks of life on the planet.
---------------- 2903 - PREHISTORIC EARTH - how did life get started?
- Dedicated chemists have devoted their careers to puzzling out the early chemical and environmental conditions that gave rise to the origins of life. With scant clues from the geological record, they synthesize simple molecules that may have existed billions of years ago and test if these ancient enzymes had the skills to turn prebiotic raw material into the stuff of life.
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- A team of such chemists have identified a single, primitive enzyme that could have reacted with early Earth catalysts to produce some of the key precursors to life: the short chains of amino acids that power cells, the lipids that form cell walls, and the strands of nucleotides that store genetic information.
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- Diamidophosphate (DAP) that’s been shown to drive a critical chemical process called phosphorylation. Without phosphorylation, which is simply the process of adding a phosphate molecule to another molecule, life wouldn't exist.
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- If you look at life today, and how it probably was at least three billion years ago, it was based on a lot of “phosphorylation chemistry“. Your RNA, DNA, and a lot of your biomolecules are phosphorylated, the same as are sugars, amino acids, and proteins.
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- The enzymes that trigger phosphorylation are called “kinases“. They use phosphorylation to send signals instructing cells to divide, to make more of one protein than another, to tell DNA strands to separate, or RNA to form. DAP may have been one of the first primordial kinases to get the phosphorylation ball rolling.
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- To test his theory simulations of early Earth conditions in the lab, using both a water base and a muddy paste set to varying pH levels. They combined DAP with different concentrations of magnesium, zinc, and a compound called imidazole that acted as a catalyst to speed the reactions, which still took weeks or sometimes months to complete.
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- For DAP to pass the test, it had to successfully trigger phosphorylation events that resulted in simple nucleotides, peptides, and cell wall structures under similar conditions. Past candidates for origin-of-life enzymes could only phosphorylate certain structures under wildly different chemical and environmental conditions.
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- DAP could do it all, phosphorylating the four nucleoside building blocks of RNA, then short RNA-like strands, then fatty acids, lipids, and peptide chains. Does that mean that DAP is the pixie dust that transformed random matter into life?
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- The best we can do is try to demonstrate that simple chemicals under the right conditions could give rise to further chemistry which may lead to life-like behavior. We can't make a claim that this is the way that life formed on the early Earth.
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- We have no proof that DAP even existed four billion years ago. We synthesized the molecule in the lab as a way to solve one of the fundamental challenges to phosphorylating in wet, early Earth conditions. For most phosphorylation reactions to work, they need to remove a molecule of water in the process.
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- How do you remove water from a molecule when you are surrounded by a pool of water which is thermodynamically an uphill task.? DAP gets around that problem by removing a molecule of ammonia instead of water.
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- Geochemists are working to identify potential sources of DAP in the distant geological past. Phosphate-rich lava flows may have reacted with ammonia in the air to create DAP, or it could have been leached out of phosphate-containing minerals. Or maybe it even arrived on the back of a meteorite forged by a far-off star.
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- One thing is clear, without DAP or something like it, Earth might still be a lifeless mud puddle. Not a pleasant thought. But, all this happened a little before my time. Here are some other reviews about mother Earth:
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- 2875 - EARTH - climate change got us here? A coupled increase in atmospheric CO2 and decrease in surface ocean pH, global warming, changes in productivity and oxygen depletion have been reported worldwide, which suggests that the scenario outlined here may be relevant to understanding future environmental and climatic trends.
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- 2869 - EARTH - waster, water everywhere? There remains a number of mysteries on our planet including the elusive origin of the blue water on the Earth. Scientists have found the interstellar organic matter could produce an abundant supply of water by heating, suggesting that “organic matter” could be the source of terrestrial water.
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- 2486 - EARTH - Third Rock from the Sun. The Sun’s energy itself is changing in its light energy. It has several cycles of its own , “Could Our Sun Be a Variable Star?” . Today we are considered to be in a normal warming trend. Global warming is claimed to be exacerbating this warming trend with human burning of fossil fuels and putting greenhouse gases into the atmosphere.
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- 2441 - EARTH - an Amazing Place? These are interesting facts about Mother Earth. Some are so amazing they are hard to comprehend. You lucked out!
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- 2383 - measurements from ICESat satellite.
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- 2033 - The Earth is doomed. Also lists 10 more reviews about the Earth, an amazing place to live.
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- 1785 - measurements from the Space Station.
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- 1721 - the closets stars and more perfect Earths.
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- 1401 - a satellite sees the loss of ground water.
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- 1295 - how the Earth was formed?
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- 1256 - why do I have earthquake insurance?
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- 1190 - thank your children for all the resource you consume.
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- 537 - the Garden of Eden
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- 511 - the density of the Earth?
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- November 13, 2020 PREHISTORIC EARTH 2903
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--------------------- --- Monday, November 23, 2020 ---------------------------
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