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Mitosis Theory


Moonchild
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Assuming all organisms that reproduce primarily via mitosis - and never by meiosis - have done so since the first few prokarya and archaebacter, and since DNA in mitosis never changes - is it possible that some, most or all single-cell bacteria that reproduce by mitosis have the exact same DNA genetic makeup as the first organisms, w/o any mutations? I mean, if the first single-celled organisms reproduced with mitosis, and there are some that never ceased mitosis, avoided meiosis and avoided other virusesand haveDNA that survived to this day since mitosis doesn't change DNA, then doesn't that mean that some bacteria, right now, on the face of this planet, are completely identical to their 4.5 bya ancestors?

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Moonchild

 

Not a chance.

 

DNA mutates. It is a fact of life, which no organism knows how to prevent totally.

 

Also the environment changes over time. Temperature, predators, parasites, diseases, competitors, even the composition of air and water. No single unchanged organism is likely to have remained successful over all that.

 

Frankly I doubt there is any organism that has been around for a long time, without some mechanism for at least occasionally sharing genetic information. It would be at too much of a disadvantage when its environment changes.

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Blame...

just a question... How can you say "Not a chance" then follow it with "is likely to have"... Either there IS a chance, or there is NOT a chance. You shouldn't have an absolute followed by a possibility.

 

Regardless, Moonchild - I think Uncle Martin is correct in stating that 'if' all of your statements 'could' happen, THEN 'yes, there is a chance'. Right back to that whole probablility thing that we like to discuss around here occasionally...

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Irish

 

You got me.

 

Ok there is a chance that a single unmutating organism could survive all environmental changes so far.

 

However you forget my first argument. All life DOES mutate. To deny that would at least require the concept of genes that can be stored and transcribed without any errors. Not ever, or at least over 4.5 billion years. There are bacteria with unusualy good error corection mechanisms*, but that good?

 

*My apologies for not finding the link.

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Irish... You got me.

 

I'm the lucky girl today!

 

Please understand that I'm not disagreeing with your conclusion. I find it HIGHLY improbable that it could/would/did happen. I guess I've just learned by now that you have to be very careful with the words you choose lest someone come along and point out your (usually MY) mistake for all to see. No offense intended, and I think you are most likely correct in your response. And don't worry about not finding the link...I have no doubt someone will post it soon enough. There are a few around here that seem to know GOOGLE better than GOOGLE knows itself...

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nonononoo!!!! noooo!

 

bacteria exchange genetic make ups..

 

its something called "conjungation" and "transduction"?... darn i forgot the spelling...

 

2 ways of getting new genetic make up:

1. obtain free genetic materials from the environment... such as the genetic make up from dead bacteria.

2. a "bridge" between 2 bacteria are built, and they exchange a tiny loop of genes.

 

edit:

i messed up with the information a little bit:

there are 3 ways of changing geneic make ups beside mutation (the usual way):

conjugation: exchange genetic materials

transformation: obtain free DNA from enviroment

transduction: virus "infection" in bacteria, changing DNAs

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