Author Topic: First organic single cell life  (Read 1193 times)

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Online bgb

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First organic single cell life
« on: June 06, 2012, 10:23:09 AM »
Having a discussion with a christian.  He asked.  "Where did the first single cell organism come from?"  Can someone help me?  Science is not my strong area.
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Offline wright

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Re: First organic single cell life
« Reply #1 on: June 06, 2012, 12:49:45 PM »
Hopefully your Christian associate isn't envisioning abiogenesis starting with a fully-formed independent cell like a bacterium or amoeba, as we now have after a few billion years of evolution. Abiogenesis likely passed through several stages before cells we would recognize developed. Here's some of the currently contending theories for how things got started and cells might have formed... http://en.wikipedia.org/wiki/Abiogenesis#Lipid_world


To answer some of the common creationist objections to the natural origin of cellular life, Talk Origins is very helpful: http://www.talkorigins.org/indexcc/CB/CB010_2.html

To sum up: life didn't begin with fully-developed cells as we know them today. The evidence we have so far suggests that various components of cellular and multi-cellular life got going and eventually came together. The first protocells did not just "poof" into existence or spontaneously assemble like a whirlwind building a 747 in a junkyard (a common creationist parody that I suspect your acquaintance is aiming at).

Life on Earth has a long, difficult history. Every "stage" that we identify was preceded and followed by constant struggle with competitors and the environment. That we can now begin to investigate our fundamental origins is humbling and exhilarating.
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Offline Gill

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Re: First organic single cell life
« Reply #2 on: June 07, 2012, 08:50:19 PM »
Having a discussion with a christian.  He asked.  "Where did the first single cell organism come from?"  Can someone help me?  Science is not my strong area.

Nobody knows how life began.

Offline mrbiscoop

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Re: First organic single cell life
« Reply #3 on: June 07, 2012, 09:03:49 PM »
http://www.amazon.com/Life-Ascending-Great-Inventions-Evolution/dp/0393338665/ref=sr_1_1?ie=UTF8&qid=1339121249&sr=8-1
 The first chapter or two comes as close as we currently know to answering this question, IMHO.
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Offline inveni0

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Re: First organic single cell life
« Reply #4 on: June 08, 2012, 08:37:41 PM »
Yeah.  Your friend has a misconception about the origin of life (as most creationists do).  Life didn't start out as complex life.  It became complex through evolution.  When someone asks me this question, I say, "There was no first cell.  Only a bundle of chemicals working together.  They accidentally copied themselves, and the bridge to complex life began."
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Offline carpunky

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Re: First organic single cell life
« Reply #5 on: June 25, 2012, 07:40:41 PM »
What really amazes me is how these complex cells made both male and female versions of every species.

It has taken a million years to make a male...we really have no clue , just a example.

Then this complex cell finds another complex cell that has created a female....but wait, did these complex cells happen at the same time ?

One would certainly die before they could reproduce if ether had to wait a 100 yrs or more, and this has to happen for every species.

I mean what are the odds ?


Offline Quesi

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Re: First organic single cell life
« Reply #6 on: June 25, 2012, 08:10:04 PM »
Welcome to the forums carpunky!

There are certainly forum members who are better equipped than I am to discuss biology.  But I did want to point out that the vast majority of living beings on earth continue to reproduce asexually, or by means that do not incorporate "male" and "female" in the way that most of us think about gender. 

Bacteria, for example, reproduce asexually.  And they represent by far the largest percentage of living beings on planet earth. 

Bacterial biomass
 
There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. In all, it has been estimated that there are about five million trillion trillion, or 5 × 1030 (5 nonillion) bacteria on Earth with a total biomass equaling that of plants.[12] Some researchers believe the total biomass of bacteria exceeds that of all plants and animals.[6][7]
http://en.wikipedia.org/wiki/Biomass_(ecology)

Plants do not have gender in the way that most animals do.  Nor do corals, which are considered animals. 

It is possible (probable?) that only one evolutionary tree contained the mutations that we consider gender.  And that is the tree that lead to the fish and amphibians and reptiles and mammals that now populate the earth. 

I welcome any of our scientists to correct or clarify any errors that I might have made, and to help our new forum member (and the op for that matter) to better understand the relationships that the complex life forms that inhabit planet earth have to the simple, original, single celled organisms that started life on earth.   

Offline Mooby

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Re: First organic single cell life
« Reply #7 on: June 25, 2012, 08:42:03 PM »
What really amazes me is how these complex cells made both male and female versions of every species.
They didn't.  There are many, many species out there that do not have male and female cells, and there are many out there that have both cells.

It has taken a million years to make a male...we really have no clue , just a example.

Quote
Then this complex cell finds another complex cell that has created a female....but wait, did these complex cells happen at the same time ?

One would certainly die before they could reproduce if ether had to wait a 100 yrs or more, and this has to happen for every species.
Yes, things would certainly be different if every organism had to reinvent the wheel.  Luckily, this doesn't happen.  When one fish species splits into two new fish species, they don't have to reinvent gills, and when one bird species splits into two new bird species, they don't have to reinvent wings.  Similarly, not every species had to invent male and female cells (gametes.)

One of the biggest drivers of evolution is natural selection, which favors organisms that are better suited to their environment.  Because of this, the more options that are available, the better the odds are that one group of options is the best fit for that environment.  Mutation is one way to create new options, but it only does so one option at a time.  By combining our options, we can make a spectrum of options.

For instance, if we start off with blue paint, and then a mutation gives us yellow paint, we only have two colors: blue and yellow.  However, if we're allowed to combine those colors, we can make a spectrum of colors in various shades of blue, green, and yellow.  If our environment likes sea green, we're more likely to approximate that if we can combine.

So then how did organisms start combining?  If we made it mandatory from the start, then how would the first cells combine?  For it to even work at all, it'd have to be optional.

And that's exactly what we find.  There are bacteria that can either reproduce by themselves or combine material with other bacteria, in a process known as conjugation.  This process only requires one cell to be "equipped" for mating, which means our cell doesn't have to "wait" around for other cells to evolve this process!

As for male and female gametes, there are primitive creatures that make both gametes, and have them combine on the same organism.  So they mate with themselves to provide different variations of their own genes.  This is a step up from conjugation, but a step down from true sexual mating.

Going another step up, there are creatures that produce both gametes but mate with each other.  Earthworms are a prime example of this.

And then, another step up, there are creatures that only produce one gamete.  This appears to be the ideal as it shows up in higher order organisms, likely because it prevents self-mating and thus maximizes diversity.

So when we look at the history of mating, it appears that this is a gradual process that became more distinct as organisms evolved, rather than something each species learned overnight.
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Offline wright

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Re: First organic single cell life
« Reply #8 on: June 25, 2012, 08:54:57 PM »
Welcome, carpunky.

What really amazes me is how these complex cells made both male and female versions of every species.

It has taken a million years to make a male...we really have no clue , just a example.

Then this complex cell finds another complex cell that has created a female....but wait, did these complex cells happen at the same time ?

One would certainly die before they could reproduce if ether had to wait a 100 yrs or more, and this has to happen for every species.

I mean what are the odds ?

You have some misconceptions about the evolution of life in general and gender specifically. In brief, evolution acts on entire populations of organisms, not just individuals. So the scenario you pose is pretty inaccurate. Like most evolution, the development of sexual reproduction was a gradual, incremental change. At every stage, there would be hundreds of millions (if not more) of the same or related microorganisms undergoing the same process, so finding a reproductive partner would not be a serious difficulty.

If you're genuinely interested and not just trolling, here's a link to get you started on what current theory has to say on the subject:  (http://en.wikipedia.org/wiki/Evolution_of_sexual_reproduction)
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Offline Irish

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Re: First organic single cell life
« Reply #9 on: June 27, 2012, 02:26:21 PM »
As to the original post:

Having a discussion with a christian.  He asked.  "Where did the first single cell organism come from?"  Can someone help me?  Science is not my strong area.

bgb,

Check out the lab page of Jack Szostak for some videos and information about abiogenesis.
La scienze non ha nemici ma gli ignoranti.

Offline Irish

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Re: First organic single cell life
« Reply #10 on: June 27, 2012, 02:29:27 PM »
One would certainly die before they could reproduce if ether had to wait a 100 yrs or more, and this has to happen for every species.

(Bold mine for emphasis)

Sexual reproduction did not evolve separately for each and every specie that uses sexual reproduction.  The character only had to evolve once and all lineages after that used sexual reproduction.
La scienze non ha nemici ma gli ignoranti.

Offline Wrec

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Re: First organic single cell life
« Reply #11 on: July 02, 2012, 09:55:25 AM »
What you need is a self-replicating molecule and some fatty acids (lipids) that spontaneously organize into a layer. These layers form bubbles, much the same way oil in water forms bubbles. The fatty acids we have in the membranes of our cells are cool, because they have different properties on either end. One is hyrdophobic and the other is hydrophilic, meaning that the fatty acids organize themselves with the hydrophilic end towards the water, and the hydrophobic end toward other lipids, effectively creating a double layer of fatty acids that separate the fluid inside the vesicle from the fruid outside the vesicle. Now insert your self-replicating molecule into the vesicle, and boom, your very first proto-cell.

At least this is the most probable way it happened. I've yet to see magic, but I've observed molecules and I know chemistry. These molecules can form in puddles of water without any organised biological process.

This is further supported by the fact that RNA (which some viruses have instead of DNA like we do) is such a molecule. You just need one of these, which when the molecule replicates, spreads the molecule to new vesicles (which can also be shown can arise more or less from the basic chemical processes) and you have yourself the basis of evolution. This is because since resources are finite, they will run out when the competition increases. Next the replicators will have a hard time to find more raw materials to replicate. The ones that are most successful will continue to replicate, the others won't. You now have evolution, and about 3,7 billion years later your friend asks you about his ancestors.

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Wrec

Offline Tero

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Re: First organic single cell life
« Reply #12 on: July 27, 2012, 01:39:38 PM »
Sexuality evolved quite early in animals. The first ones had both male and female parts and were not complicated. Think earthworms.