Question

Much research has been published showing that if the prescribed doses of an antibiotic are NOT taken to completion, a strain of bacteria resistant to that specific antibiotic is likely to develop. Why does this research support the commonly accepted theory that organisms all share a common line of descent?

Answer 1

Drug-resistant strains all have the exact genetic sequence.

Exposure to environmental factors will produce beneficial mutations.

Only the resistant organisms will reproduce.

The surviving bacteria have adapted to the presence of the antibiotic.

Answer 2

those are the choices

Answer 3

Well, the question is talking about a "common line of descent."

In other words, it's talking about genetics.

And the choice that most CLEARLY involves genetics is the first choice.
That's why I personally lean on that choice.

But I DO have doubts.

Because the drug resistant bacteria would definitely have some genes in common.
I just don't know if they would have the EXACT SAME genetic sequence.

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I wish I could offer you solid answer. But I'm very curious, myself.

Answer 4

Hmm, in my opinion, drug resistant bacteria will not have the exact genetic sequence because there are some bacteria with multiple drug resistant gene so each will survive at different conditions if they have the resistant gene. Bacteria get these genes via transformation, transduction and conjugation.

Also in natural selection, those that cannot survive in the presence of antibiotic will die, leaving those bacteria with the drug resistant gene to survive and spread.

There are also mutation occurs during DNA replication since there will be error in replication for every 1 out of 10^9 nucleotides. This make bacteria strain to have different sequences although they are from same species and family.

I am not familiar with evolution but I hopes this help.

Answer 5

If the surviving bacteria have adapted to the antibiotic and are able to reproduce, they still remain the descendants of the same line of organisms. Survival of the fittest doesn't remove the line of inheritance. I would say a combination of the last two answers makes the most sense.

Answer 6

*natural selection/(survival of the fittest)

Answer 7

I think that because the genetics of all organisms is 98% (or somewhere in the 90's, can't remember) similar, and when they become mutated and acquire resistance to anything, it is a slight difference. Both types originated from one strain, and only a certain percentage died, and the rest (of the same strain, which originally had the same genetic material) changed just enough or had a few select chromosomes that gave them the traits for resistance. I'm not sure if I'm communicating my idea effectively.

Answer 8

Are you saying that bacteria will only develop beneficial mutations AFTER they are exposed to the antibiotic?

Answer 9

No, some have them. But if they are all the same strain of bacteria, they will all have mostly the same genetic material. The differences will be smaller. Which is why they are of the same "strain".

Answer 10

In fact, those who have the resistant gene are typically the only ones who survive, especially if the gene is in the plasmid or in the central DNA and becomes activated. They might develop a mutation though.

Answer 11

So how is it that the bacteria would have adapted to the presence of the antibiotic?

Answer 12

What I think is that the antibiotic would accelerate the RATE of mutations.

But at the same time, the mutations would be random.

Is that right?

Answer 13

It's possible. Bacteria replicates itself exactly because there is no mitosis, but I'm sure it has to do with transduction and conjugation. It could also be the plasmids that are activated in those who have the resistant gene (on the plasmid). I am so new at this that I'm not sure.

Answer 14

Mmm, ditto.

Answer 15

Recombination makes the most sense to me. I don't think that the presence of the antibiotics cause mutations (although I very well may be wrong), I think that through conjugation and transduction, bacteria, which already multiply at a very high rate, can acquire new traits very quickly if they are beneficial. This is all speculation on my part.