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jerrywickey

"How Life Began" -- History Channel

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History channel aired the show "How Life Began" will air again 10 PM Saturday June 21

 

Very disappointing. Full of platitudes and they spent only one minute on the very title of the show, "how life began." It took place behind a curtain about which the narrator commented that no one understands how life began.

 

 

I think the show should have gone more like this. Perhaps anyone can chime in and suggest errors I made.

 

 

1) chemicals and condition necessary for abiogenesis

 

????? presto chango -- ABIOGENESIS of one or more first replicators over perhaps 100 to 500 million years ???????

 

2) first replicators adapt to acquire nutrients and avoid fatal circumstances

 

3) replicators successful at step 2 utilized DNA as info storage and developed RNA transcript and protein coding expression regulatory mechanisms

 

4) somehow all alternate expression mechanisms ceased leaving only the one we see today.

...............and

gene splicing mechanisms developed so that separate organisms could share genes

 

5) earliest life we observe, first O2 producing algae, complete with DNA promotion, transcription, genetic code for translation and gene splicing mechanisms that we see today.

 

6) gene splicing rotates and tests genetic combination for perhaps 3 billion years but accomplishes little.

 

7) about half a billion years ago something happens in a geologic blink of an eye that 3 billion years of gene splicing was unable to accomplish, all life categories we see today emerge.

 

8) today

 

 

This still doesn't address exactly how life began. Of course, that is a mystery as the show said. No one knows and no one has yet demonstrated a suitable first replicator molecular system.

 

Jerry

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I found the below useful, and a good (although, very high-level) overview for those not very familiar with the topic. It was framed in the context of defeating the religious angle, but it does go into the basics after a minute or so:

 

http://www.youtube.com/watch?v=ozbFerzjkz4&feature=related

Well one problem with that video i see already is that when the chemicals were put together and made nucleotides they were not in conditions similar to the early earth, they were under the opposite conditions to what scientists believe the early earth was like, they were under oxidising conditions and the early earth was reducing.

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the narrator commented that no one understands how life began.

I think it is more the case of that there a re many different and plausible methods of how life could begin, but it is that we just don't know which if them is the one that actually happened.

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But each can be evaluated for probability. It's not like they are all on equal footing. Some are definitely more plausible than others.

 

 

This comment is more to supplement Ed's point than to challenge it.

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But each can be evaluated for probability. It's not like they are all on equal footing. Some are definitely more plausible than others.

You are right. And this is also why we have a "flavour of the week" situation with the different theories. Something will be discovered that will make one theory more likely (say knowing what types of chemicals were in the atmosphere, or that a type of clay can catalyse certain reactions) than another. But as new discoveries are made all the time, this leads to one theory being replaced as the most likely by another (only to be replaced when another discovery is made).

 

This makes it easy to construct the strawman argument that "Scientists have no idea how life got started".

 

It is not that we don't have an idea, it is exactly the oposite, it is that we have so many. :eek::doh:

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History channel aired the show "How Life Began" will air again 10 PM Saturday June 21

 

Very disappointing. Full of platitudes and they spent only one minute on the very title of the show, "how life began." It took place behind a curtain about which the narrator commented that no one understands how life began.

 

 

I think the show should have gone more like this. Perhaps anyone can chime in and suggest errors I made.

 

 

1) chemicals and condition necessary for abiogenesis

 

????? presto chango -- ABIOGENESIS of one or more first replicators over perhaps 100 to 500 million years ???????

 

2) first replicators adapt to acquire nutrients and avoid fatal circumstances

 

3) replicators successful at step 2 utilized DNA as info storage and developed RNA transcript and protein coding expression regulatory mechanisms

 

4) somehow all alternate expression mechanisms ceased leaving only the one we see today.

...............and

gene splicing mechanisms developed so that separate organisms could share genes

 

5) earliest life we observe, first O2 producing algae, complete with DNA promotion, transcription, genetic code for translation and gene splicing mechanisms that we see today.

 

6) gene splicing rotates and tests genetic combination for perhaps 3 billion years but accomplishes little.

 

7) about half a billion years ago something happens in a geologic blink of an eye that 3 billion years of gene splicing was unable to accomplish, all life categories we see today emerge.

 

8) today

 

 

This still doesn't address exactly how life began. Of course, that is a mystery as the show said. No one knows and no one has yet demonstrated a suitable first replicator molecular system.

 

Jerry

 

 

Its not that we don’t have any idea, its just a rather complex question;)

 

With that being said if you look at organic synthesis for instance you might start to find various reaction mechanisms that are many step and have various conditions that need to be met such as ph and of course time or thermal conditions. so in reality the chain of reaction that may have lead to life originally might not just be one continuous mechanism but say for instance that you had to have three different mechanisms, each one bearing its own complexity, to add to this what if the whole deal of reactions for just one part takes say 50 years to complete!

 

looking at organic functional groups I do not find this hard to imagine. I don’t know of many reaction mechanisms in the real world that are over say 1000 steps. I don’t know if its fair to label something like that a reaction mechanism but hey I don’t know all the words to use in such a situation.

 

Plus its probably not all just chemistry. what if it involved a proto virus like entity coming into contact with say protobionts in some kind of a nutrient rich patch.

 

again the question is vastly complex and blurs the line of what can be called life being virus entities have been created from scratch. Not to be to rude on the question but you might even find yourself having to do quantum engineering type equations and stuff or nanotechnology. I mean what happens if you have a few amino acid chain reaction going on and you add in an iron ion containing group, its not something that’s going to be solved by tomorrow at any rate. I think a good place to study is metabolism that can retain some sort of heredity, maybe with thermophiles.

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is also quite good.

 

One thing I didn't understand in that one: Why did the cells not "want" to lose lipids?

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I was just about to start a new thread on a similar topic, but this one will do!

 

I have been thinking about which came first - the gene or the protein that allowed the gene to be transcribed and translated?

 

I have read something about autocatalytic replication of RNA, but subsequent events become a little hazy.

 

Somebody out there must have a hypothesis...

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I was just about to start a new thread on a similar topic, but this one will do!

 

I have been thinking about which came first - the gene or the protein that allowed the gene to be transcribed and translated?

 

I have read something about autocatalytic replication of RNA, but subsequent events become a little hazy.

 

Somebody out there must have a hypothesis...

 

There is no real consensus that I know of. You have a small list of competing ideas about how it started. I think it boils down to trying to reduce say evolution to microorganism level and then looking for clues there, such as does a thermophile have the most basic metabolism to support life, or the other side of the coin tries to figure out how life could be supported from the chemistry level looking up, and combined with this you have various experiments, such as what lead to protobionts.

 

Its just what something like that video lacks or any current documentary on the issue is really the complexity involved. A modern metabolic pathway in say some minor bacteria can be mind boggling really, simple put it relates to behavior from a cell for instance. So just in terms of trying to reduce that chemistry to something primordial is really a difficult task i would imagine. I mean just cutting out Anaerobic respiration by itself wont help for instance.

 

Then trying to build something like a cell from a chemistry viewpoint? Its not going to happen tommorow:D Its not impossible but at the point we could recreate how life evolved on earth to the point of being able to make a living cell would imply a huge technological advantage to where we currently sit technology wise. Just our understanding of nanotechnology alone would have to be rather astounding compared to its current place.

 

So in short I don’t think anyone could answer your question really past a hypothesis.

Edited by foodchain
- an f

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foodchain thanks for the answer. I agree with you and it is a difficult point to answer. However, I suppose it is possible for RNA to code for a protein which then subsequently specifically modifies the activity of the RNA so perhaps I have answered my own question partially. It's just a matter of hypothesising when DNA came into the picture. However, I do take your points on board about the sheer complexity of the simplest biochemical pathways in bacteria.

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One thing I didn't understand in that one: Why did the cells not "want" to lose lipids?

It was not that the cells didn't "want" to loose lipids, it is just that cells that lost the lipids didn't reproduce as fast. Because they didn't reproduce as fast, then the cells that had the lipids would reproduce quicker and out compete them.

 

It is just a short hand way of summing up the complexities of what is going on.

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It was not that the cells didn't "want" to loose lipids, it is just that cells that lost the lipids didn't reproduce as fast. Because they didn't reproduce as fast, then the cells that had the lipids would reproduce quicker and out compete them.

 

It is just a short hand way of summing up the complexities of what is going on.

 

Right I just didn't get why cells with more lipids would reproduce faster. I figured it out, though. It's the mechanism of reproduction: The more lipids, the bigger the vesicle, the more likely it would break apart and carry the nucleotides with it.

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