The fun thing about that is there’s no way of knowing if the third item is meant to be that way or not!
I get dyslexic under stress, so I often don’t notice typos since I’m used to reading my own notes with scrambled letters . . . but then unscrambling can be dyslexic as well; the second word could get taken to be “lures”.
Perhaps because all science relies on math, so people expect that participants here should demonstrate at least a high school level of math comprehension.
If it was only three mistakes, rather than eleven, one might assume difficulty in expressing concepts, but with so many in such a small space that hypothesis is difficult to support.
You and two others (who I do not need to name) seem to take great delight in (trying to) put(ing) me down. I may let atheists off, but you should know better.
So you ignored my response(s).
So it appears that you and he cannot count. Shame that is a basic mathematical skill.
(Now please drop this. You do neither of us any favours)
T_aquaticus
(The Friendly Neighborhood Atheist)
368
Pointing out where people are wrong isn’t putting them down. There are times I am wrong about certain things, and I appreciate those who point out where I am wrong.
There were only a relative few generations from that single bacterium to the appearance of phage resistant bacteria.
What caused the appearance of phage resistant bacteria. This strikes me as essential as I assume no external factor operates in this experiment.
The bacteria that were sensitive to phage were killed by the phage. They essentially pop like balloons. That leaves the phage resistant bacteria to reproduce and pass on their phage resistance mutation.
Again, were the phase resistant bacteria formed spontaneously without an observable cause? From your next comment:
In the induced mutation model, the interaction with phage induces a specific mutation that results in resistance. Since all bacteria would presumably have the same system that induces a specific mutation in response to phage…
I assume that the resistant strain formed after your sample was exposed to phage – this is the difficulty that I see thus far. If the phage causes the formation of a small portion of the sample, there must be a time delay in the ‘popping like balloons’ action. i.e. the rate of popping should be compared to the rate of formation of the new resistant species. They concluded that a ‘spontaneous’ event occurred……
The results of the experiment matched the large fluctuations predicted by the spontaneous mutation model.
Such a conclusion must mean, as I see it, that resistant strain could spontaneously occur with or without addition of phage. Perhaps studies on the initial sample under high magnification may identify the formation of the spontaneous species, but I cannot see this in what you have provided. Your initial comment seems to contradict a spontaneous event (ie a few generations from …)
If there’s an error in the above-quoted paragraph, please point it out. I can’t see one. I definitely can’t see a miscount in that paragraph. The only number mentioned is “one”.
So what have I miscounted?
T_aquaticus
(The Friendly Neighborhood Atheist)
373
The cause is a mutation, a change in the DNA sequence of the E. coli genome. Of course, this experiment was first done in the 1940’s, so they didn’t have an understanding of the molecular basis of heredity. However, what they observed was phage resistance that was heritable and bred true for many, many generations.
Luria and Delbruck weren’t able to sequence DNA, so they wouldn’t have been able to measure the mutation. All they could see is a heritable trait. However, we do have that ability now and we know of mutations in the fhuA gene in E. coli that gives rise to this very same type of phage resistance. We also understand the causes of mutations, and they are spontaneous in the sense of any spontaneous chemical reaction.
That’s exactly what the experiment was set up to test, whether the mutation happens when the bacteria are exposed to phage or if they already had the mutation when they were exposed to phage. Those are the two models that I spoke of earlier: induced mutations and spontaneous mutations. You are proposing induced mutations in the part I quoted above. This would predict about the same number of resistant colonies over many experiments. If the mutation had already happened prior to being exposed to phage then you would get a lot of variation in the number of resistant bacteria from experiment to experiment because the mutation could happen in any number of generations. If the mutation happens in an early generation then you get lots of resistant bacteria. If it happens in a later generation then you will have fewer resistant bacteria.
I don’t think we have the technology necessary for watching DNA mutations as they happen.
1 Like
T_aquaticus
(The Friendly Neighborhood Atheist)
374
I understand your position just fine. I disagree with it.
You seem to be under the impression that if people just understood your beliefs they would believe the same thing. I don’t see why this would have to be the case.
But you see to think that anyting i say or believe must be wrong
(And anyting you say or beleive must be right)
Richard
T_aquaticus
(The Friendly Neighborhood Atheist)
377
That’s not true. I’m sure there are many things you say that are correct. When you say things taht are wrong I point them out as being wrong. Why is that a problem?
The problem is that you make everything personal. People keep correcting you not on the basis of any belief that they are “the holder of all truth” but on the basis that objectively things are one way and not another. It has nothing to do with opinion, it has to do with how things are actually defined, e.g. probability and statistics.