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Author Topic:   Application of the Scientific Method: Antibiotic Resistance
Faith 
Suspended Member (Idle past 1444 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


(1)
Message 4 of 20 (691876)
02-25-2013 11:53 PM
Reply to: Message 3 by Taq
02-25-2013 3:45 PM


Re: This is peer reviewed
I almost feel bad that I'm not joining in on this thread since you've invited me so many times, but I just can't relate to bacteria. For one thing they don't have enough junk DNA. Not "one of us" you see.
This particular example you are using here has been discussed before only I do have to say I don't remember the outcome. Supposed to prove that mutations happen on cue just when needed as usual I guess?

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 Message 3 by Taq, posted 02-25-2013 3:45 PM Taq has replied

Replies to this message:
 Message 5 by Taq, posted 02-26-2013 11:15 AM Faith has replied

  
Faith 
Suspended Member (Idle past 1444 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 6 of 20 (691922)
02-26-2013 11:45 AM
Reply to: Message 5 by Taq
02-26-2013 11:15 AM


Re: This is peer reviewed
Bacteria have junk DNA as well. They use the same basic genetic and metabolic systems we do. I really don't see why this is a problem.
I'm sure I read somewhere maybe Wikipedia that they have a lot less junk DNA than we have, a LOT less. It seems to me that this gives them a huge advantage over us, many more genetic possibilities that couldn't be extrapolated to our situation, maybe even the ability to mutate on demand or something like that. Not to mention that although I know there are "good" bacteria most of them seem to be out to kill us (E COLI???) so that I have a big problem identifying with them. (Half kidding, Taq, but it's also true).
This particular example you are using here has been discussed before only I do have to say I don't remember the outcome. Supposed to prove that mutations happen on cue just when needed as usual I guess?
That is certainly one hypothesis we can test. It is also one of the hypotheses that scientists seriously considered when faced with the observations found in the opening post.
So let's develop that idea a little bit. To be "on cue" it would appear to me that the mutations should be a reaction to the presence of antibiotics. That is, we should be able to tie the introduction of antibiotics to the appearance of the mutation. In fact, we don't even have to say that it is a mutation. This could just be a hidden phenotype that is turned on by the presence of the antibiotic.
Does this sound something like the hypothesis you would put forward?
I just find bacteria to be so alien it is very hard to come up with a hypothesis at all. And here you've got this down to a single cell as the progenitor of all the millions? How on earth does that compare to anything in the multi-celled kingdoms? How could an alternate phenotype be "hidden" in a single cell? In a phenotypically diverse colony, OK, but see I can't even be sure I'm talking about anything that could be compared to a multi-celled creature's situation at all.
I suppose given the description I'd be inclined to think in terms of mutation on cue just as suggested.

This message is a reply to:
 Message 5 by Taq, posted 02-26-2013 11:15 AM Taq has replied

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 Message 7 by Taq, posted 02-26-2013 12:03 PM Faith has replied
 Message 8 by New Cat's Eye, posted 02-26-2013 12:05 PM Faith has replied

  
Faith 
Suspended Member (Idle past 1444 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 9 of 20 (691925)
02-26-2013 12:10 PM
Reply to: Message 8 by New Cat's Eye
02-26-2013 12:05 PM


Plants
This is off topic for this thread but if you want to take it over to my thread I'll respond there.

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Faith 
Suspended Member (Idle past 1444 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 10 of 20 (691928)
02-26-2013 12:27 PM
Reply to: Message 7 by Taq
02-26-2013 12:03 PM


Re: This is peer reviewed
How could an alternate phenotype be "hidden" in a single cell?
The same way that it is hidden in animal species. Bacteria, just like animals, can change gene expression in response to a changing environment. They can alter their phenotype in response to physical cues just like animals do.
Taq, this sounds like a completely other theory of evolution than I'm familiar with.
The WAY I understand animals to "change gene expression in response to a changing environment" is by the reproductive selection of alleles that are best fitted to the new environment which can mean those not fitted have to die out before reproductive age, and all this is supposed to be more or less random. You keep talking as if there were some sort of PURPOSIVE or teleological ability to change the phenotype on demand that I always thought was rejected as a misunderstanding of how evolution works. All the processes are supposed to be random. If nonadaptive types die out before reproduction, then the alleles that are favored by the environment that are reproductively successful will have the opportunity to be expressed in greater and greater numbers until they come to characterize the population.
This is possible in multi-celled sexually reproducing animals that possess the "hidden phenotypes" for such adaptations, probably most often in the form of recessive alleles, perhaps for more than one gene, or perhaps dominant alleles have to work together with other genes to come to expression or something like that. In any case you have to have a situation that allows the adaptive alleles to find opportunity for expression which is usually because the nonadapative individuals aren't reproducing as much.
Isn't something like that the usual idea?
How a single cell could manage such a feat I have no idea. It WOULD have to change in response to the environment in some much more direct way it seems to me.
If you don't jmean to be implying something so directly teleological maybe it would help if you reworded it.
I suppose given the description I'd be inclined to think in terms of mutation on cue just as suggested.
So what we need to do is determine if the mutation conferring antibiotic resistance occurs before or after the bacteria are exposed to antibiotics, correct?
Hm. OK I guess. But even so it's hard to imagine that mutations that save the creature from death just turn up so fortuitously, whether right before or whenever they are "just in time." If before then it wouldn't be in response to the antibiotic of course, but why they should occur at all at such a convenient time is still rather mystifying. It seems to violate the rule of randomness. AND the other "rule" that I thought says that beneficial mutations don't occur all thjat FREQUENTLY.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.

He who surrenders the first page of his Bible surrenders all. --John William Burgon, Inspiration and Interpretation, Sermon II.

This message is a reply to:
 Message 7 by Taq, posted 02-26-2013 12:03 PM Taq has replied

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