Quote:
Originally Posted by
Darthtang AW http:///t/396331/private-schools-and-evolutionary-theory/80#post_3531376
If all living things evolved from one organism, where does plant life turn into "animal" life. And what is the progression of evolvement (is that a word) of plant life?
Now I'm repeating things that I have been taught. I have not done any of my own personal research nor do I have any experience with it beyond it being in a book... I'm going to use wikipedia as references, but anyone with two brain cells can go and dig through scientific journals.
The Miller-Urey experiment was one of the first experiments that replicated early conditions of life on Earth. (http://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment) In this experiment, they put elements into a series of tubes and heated and cooled everything in various conditions and even shocked it with electricity to replicate lighting scenerios. At the end of the experiment, vials were collected and tested in the lab. Within the vials contained 20+ different types of amino acids that are the building blocks of proteins. have a protein put it together and they form peptide bonds. Put many of these peptide bonds together and you come with with secondard, tertiary and quarternary structures that form various proteins. RNA, Ribosomal Nucleic Acid is also a very, very simple compound and is now thought of to be one of the first organic molecules to come into existance, because early RNA didn't have to have proteins to cleve itself, it could do it on it's own. DNA was the next thing to form - and it's so simple because if RNA is already existing, then all it takes is to add an oxygen molecule to a five carbon sugar and you get Deoxyribose Nucleic Acid. DNA is a double stranded helix, and it doesn't take much to reason that DNA was the prefered information storage molecule because it's much more stable with the additional oxygen molecules. RNA started to associate with these strands and began to make proteins through Ribosomes... early replication. Since ribosomes are nothing more than long strands of RNA in a quarternary structure with associated proteins, it's not hard to think that these molecules would not want to interact with DNA. Through trial and error, Natural Selection and natural chemical occurances, a phospholipid bilayer was formed so that DNA, RNA and proteins would have at least some protection from the environment. Now, this is the first cell.
As far as scientists have been able to test for, a type of cyanobacteria was one of the first organisms on Earth. This is great, because it was able to "fix" nitrogen in the atmosphere and use it to it's advantage. Over time and through allopatric speciation, other cells began forming with their own functions - like mitochondria organelles actually are now theorized to be bacterial cells that early Eukaryotic organisms engulfed and figured out that it's a highly beneficial cell (makes ATP, or useable energy.) That's considered horizontal gene transfer. http://en.wikipedia.org/wiki/Horizontal_gene_transfer . Chloroplasts - those pretty green looking pigments in plants, are also one of those early bacterial cells that were engulfed by early Eukaryotic cells. Eventually, there has come to be ____ different types of organisms on earth, and probably many more to be discovered: Prokaryotes like bacteria, archaebacteria, protista and Eukaryotes like plants, animals and we will put fungi to the side... Plants got the chloroplasts and mitochondria, animals are sans chloroplasts and got mitochondria to respire. So on and so forth.
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Plants developed around the ability to harness the power of light to make organic carbon molecules like glucose (sugar), but depend on bacteria in the soil to fix nitrogen into useable forms. Harnessing light doesn't require the ability to move, but to out-compete it's neighbor for space, nutrients and light. Therefore, they went down a different evolutionary path than animals did. Animals don't have the ability to make their own food, so they have to catch food - or move - in order to compete with their neighbors... so evolution selected for animals who were faster, stronger, better equipped or smarter in order to survive - hence natural selection being one of the driving forces for evolution.
I hope all of that made sense. If it doesn't, I'll try to clarify on any points. Chemistry and time...
Now, saying all that, and knowing in my head that it all makes sense because of my education doesn't say that I don't believe in God. I think S/He exists, but I don't think that S/He has no interest in our affairs.
