[00:00.00]Listen to part of a lecture in a biology class.
[00:03.96]Professor: Now, organic compounds, we'll talk first about amino acids and their molecular composition. [00:10.59]Since they make up their the building blocks of proteins, and all living organisms depend on them, human life wouldn't be possible without them.
[00:19.42]But first, I want to was maybe a little peripheral to our main concerns, but it's intriguing, at least. [00:25.74]I think it's interesting to think about. [00:27.35]It's also fairly controversial. [00:29.46]The question of how they arose, how organic compounds originated on earth. [00:35.41]And of course, there is several theories. [00:38.27]One theory says, we know these compounds are composed of carbon and hydrogen, right? [00:43.54]That's why we consider them organic. [00:46.19]But one idea is that they came originally from inorganic elements that amino acid can be, in fact, were created out of non organic components, that these non organic parts were present as separate elements on early earth. [01:01.69]And later combined in such a way to form organic compounds like amino acids. [01:07.14]But there's other evidence that says that points to meteorite as a source of organic compounds, on earth.
[01:14.47]Now, the idea that non organic elements combined really took cold when you may have heard of the Stanley Miller experiment.[01:25.90]In 1953, Miller, and he's graduate student at the University of Chicago. [01:29.18]And he has an idea that the first organic compounds might have formed from non organic compounds. [01:35.46]And he sets out to show how. [01:37.25]So he puts together an airtight apparatus, and he puts in water and a mixture of four gases, methane, ammonia, water, vapor, and hydrogen. [01:48.48]Those were the gases that were then thought to have composed the atmosphere of the earth in its early stages. [01:54.28]Okay? And he hooks up some electrodes to this system. [01:58.39]And for a week, he cycles the mixture through the apparatus and subjects it to intermittent jolts of electricity. [02:05.98]A week later, he analyzes the contents of the chamber, and he discovers that he's produced organic compounds. To check his results, he then conducts two control experiments. [02:18.55]He needed to rule out the possibility that the gas mixture was contaminated, that it contained trace amounts of organic elements. [02:26.50]So in the first control experiment, he sterilizes the gases for 18 hours at 130℃. [02:33.60]Before he subjects them to electricity, then he follows the original process, and he gets the same result. [02:41.39]So no contamination. [02:43.82]And then in his second control, he ran the experiment just like the original experiment, except without the electricity. [02:51.06]The the same mixture were water and gases, but he doesn't run electricity through it. [02:56.14]But this time, no organic compounds were produced. [03:00.17]So it seemed that electricity was a critical part of creating the organic molecules in his original experiment that provided the energy needed to combine the basic inorganic elements. [03:12.53]So this could show how it all got started on earth, right? [03:17.28]You've got water and these basic atmospheric gases, and they get struck by lightning. [03:22.61]And bingo, organic compounds are created, and you've got the building blocks of life, not life itself, just some of the necessary elements for life.
[03:33.28]Now, one criticism of miller's experiments was um, was that, well, later on, it was shown that the composition of earth early atmosphere was a bit different from the mixture of gases that Miller used. [03:46.95]But still, there have been experiments since then, which suggests that if you take the elements that we now think were present at that time, and subject them to some kind of burst of energy, whether it be from um, lightning or or from cosmic radiation or from extremely high temperatures or whatever that you can get simple organic compounds produced. [04:09.39]You get the same result the Miller got. [04:10.56]In organic elements, plus energy, yields organic compounds. [04:16.46]Okay? Not conclusive, but interesting, right? [04:21.81]But then you also have proponents of the meteorite theory. [04:26.64]Earth was bombarded with meteorite between about 3.8 billion and 4.5 billion years ago. [04:34.59]And there's some evidence that meteorite may have brought with them a number of elements that are critical for life. [04:41.47]Oxygen, sulfur, hydrogen, nitrogen, and organic compounds. [04:47.33]Um, and just a few years ago, they found a couple um meteorites that contained sugar related compounds, which uh, as will later study are critical to all known life forms.
[04:59.41]Okay? So two very different ideas about how the basic building blocks of life might have arisen on earth.
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