Re: Good Mutations.

Moorad Alexanian (alexanian@UNCWIL.EDU)
Tue, 02 Dec 1997 14:15:42 -0500 (EST)

At 07:43 AM 11/27/97 -0600, R. Joel Duff wrote:

>I often get the same question. I answer with a question: What do you mean
>by mutation? I find that most of the time the person is either overtly or
>subconciously defining a mutation as something detrimental to the organism
>thus cannot conceive of a mutation doing "good." Good and bad mutation are
>highly subjective terms depending on what we think is progress. Point out
>that there are many types of mutations: point mutation, chromosomal
>mutations etc... In each catagory there are mutation that are detrimental,
>helpful, or effectively neutral to the survival (fitness) of the organism.
>Off the top of my head I would give a bacterial example:
>If you plate some bacteria on a media with high salt all will die but a
>couple. These potentially had mutation that allowed them to survive. Take
>a single bacteria and grow it up and plate it on a media with double the
>salt concentration and most of them will die but a few may survive. Most
>of them were genetically the same as the original bacteria and couldn't
>handle the higher salt concentration and so the few that survive you may
>surmise had some sort of mutation. Is this a "good" mutation? It is if
>you are interested in bacteria that live in high salt environments. It
>isn't if you didnt' desire the bacteria to live.

I am not sure I understand. Is it possible that the bacteria have a sort of
bell-shaped curve of characteristics that determine what the bacteria is and
by means of environmental changes we can select the parts of the bell-curve
which we desire. Sort as animal breeding. Do we indeed have to talk of
mutations? Can we tell at the molecular level? What makes us say that we are
dealing then with the same bacteria?