You brought a really good point about the 32 - 23 chromosomes; my answer is some of them would become useless thus discarded.

An individual with chromosome disorders may have some different traits from its relatives, but the chromosome disorder may not affect the individual's ability to have offspring and ability to find a mate. Example.

Mutations do not involve entire chromosomes, you're thinking of things like down syndrome and stuff, yeah? That's not the same type of mutation as we are talking about in evolution, as I will explain. They consist of T, C, G, & A. Ts can only coincide with Cs and As can only coincide with Gs. Though I think I may be oversimplifying it there.

so here would be a little snippet of a chromosome.

T - C
A - G
G - A
C - T

Another thing then comes along and 'reads' this code by taking only three of the letters on one side. So if it took the first three for the above chain on the left side the code would be TAG, and the right side would be CGA. TAG would be a code to go make a certain enzyme and CGA would be a code to make some other protein or whatever.
One chromsome consists of chains way, way, larger than the one I just gave you. A mutation is just when one of those codes changes, thus changing the overall three letter code and making something entirely different be created instead.

I hope this makes sense, I tried to sorta put it in laymen's terms as much as possible. I will be happy to go into more depth if you want.

EDIT: Nice Wiki picture showing notable mutations that often occur with humans. I think it will reinforce what I have explained very well.

See how only one letter has to change in the three letter code to produce an entirely different chemical? That is a mutation.


Uh also just want to clarify in the picture there is a U in place of a T. That is because in RNA it is a U, it is DNA that is a T.

Post has been edited 3 time(s), last time on May 27 2011, 11:30 pm by Oh_Man.

You're trying to make the case that not all mutations are bad, and then you show us a chart of nothing but bad mutations?

If you look at the chart, you can see that some amino acids have several different base combinations. If your DNA codes for a certain amino acids, no matter what are the bases, your body will still use that amino acid to make a protein, and the amino acid will always work normally no matter which combination codes for it. For example, you can see on the chart that Phenylalanine is coded by both UUU and UUC. If a mutation changes your RNA from UUU to UUC, nothing happens. The resulting amino acid/protein is still the same.

Ahh, but my point isn't that a TGCA can't turn into a TCGA, my point was that a TGCA can't turn into TGCA-TGCGATCG
If different animals have different lengths of chromosomes, you are assuming that new strands of DNA could have just appeared or disappeared, as opposed to changing to something else.

This has been my argument all along. I don't have a problem with natural selection. I have a problem with genes being added or subracted and assuming that they will both have positive effects on the individual specimen, too the point where they would be more successful than their relatives and still be able to produce offspring.

Well you shouldn't, because it has been demonstrated in laboratories that genes are added, deleted or changed, and that this can have beneficial effects on the organism (and also deleterious effects). See also: anti-biotic resistant bacteria, fruit fly genome mapping and evolution. At best, you might argue that what applies to insects and bacteria doesn't apply to animals and higher organisms, but I think you'd be hard pressed to come up with some logical reason for to assert that although the different types of organisms have DNA that works in much the same manner in all other aspects, the DNA of bacteria/insects can somehow undergo mutations while higher organisms cannot.

Oh, so sometimes something bad doesn't happen; nothing happens. How are we showing beneficial mutations again?

I'm saying that sometimes things go like that. Good mutations can occur if a mutation turns the DNA into the code for a better protein.

Again you aren't getting the point. It's not that They can't mutate, it's that they would not be able to reproduce in that mutated state. Their DNA would be longer or shorter than the mates, and it wouldn't not combine correctly. At best, it would be some weird half way in between thing, and it still wouldn't be the same as the original mutant. i.e. if a horse (32 Chromsosomes) mutates from a donkey (30 chromosomes), and since it's the only horse on the planet, it would have to breed with a donkey, and the result is a mule (31 chromosomes) This is the only example I know of where two animals reproduced with different numbers of chromosomes, and the resulting animal cannot reproduce because of it.
Bacteria does not suffer from this problem because they reproduce asexually. The newly mutated bacteria would keep it's mutations unless it died or lost its ability to multiply.

And fruit flies?

I don't know why you're so hung up on addition or deletion of chromosomes. Those are very very big mutations that happen rarely. I'm sure there are theories that adequately explain how it is possible - we aren't all biochemists here, you know (except maybe Faz).

Yeah I already explained this in my last post, we are not talking about entire additions of chromosomes. Just additions of those base pairs. One addition of them is not enough to stop them to reproduce. Over time, more and more additions keep getting added until they would be unable to reproduce with their old population, this is when they are characterized as a new species.

Makes sense?

No, your post is about changing genetic code not adding to it. If you take 100 and subtract 1 and then add 1 again you aren't going to get 101.
I haven't heard of any group of people having longer or shorter segments of genetic code, just different swapped out pieces. And yes, adding one gene would make a big difference in a genetic code, unless one was first removed. It would offset every digit afterwards and would make something completely different that I'm guessing would kill it, so theres about a 1 in 3 chance that a set of 3 digits would be added. Even now, we have the technology to alter DNA to make plants grow bigger faster, and make cats that glow in the dark, but none of these genetically altered species are able to reproduce. Could it be that maybe they are unable to reproduce because their DNA is a different length?

You state that evolution is "still only a theory," but I must ask: as opposed to being what? Do you realize that the scientific definition of a "theory" is completely different from the colloquial definition you're familiar with? Evolution is just as much of a theory as quantum mechanics, electromagnetism, and gravitation are.

And what you're referring to is not evolution but abiogenesis, and they are in no way related. Evolution describes the behavior of life that's already there. It's like asking a psychologist to first explain where the human species came from.

Excuse me if I'm completely wrong about this as I lack familiarity with biological concepts, but don't retroviruses add information to the host cell by inserting their own DNA sequence onto an arbitrary point on the host's DNA?

Post has been edited 4 time(s), last time on Jun 4 2011, 7:27 am by grAffe.

Consult the chart Oh_Man posted some posts earlier. Every 3 consecutive base pairs on a strand of DNA codes for an amino acid in the way shown in the chart, and amino acids are attached to each other to make proteins. Now the problem with DNA is that mutations aren't that uncommon, so the DNA includes strands of completely unused DNA, called introns, which are removed during RNA replication. When a mutation occurs on an intron without tricking the cell into thinking the modified intron is a piece of useful DNA, the cell is unaffected. When the amount of genetic code in a strand of DNA is changed, the "ripple" of changed DNA code only affects along the direction at which enzymes read the DNA strand, not necessarily the whole or most of the DNA strand.
When an organism is mutated or genetically engineered, it will only be rendered infertile if the changes to it protein directly affects its ability to mate, find a mate, develop functioning sex organs, or its ability to survive long enough to have children. For example, a mutation that makes a man's semen neutral or acidic (semen is normally slightly basic due to the amount of alkali in it) may make him infertile, while a mutation that makes him have a lot more digits may not.

I'm not so familiar with viruses. I know they are made out of DNA. I'm fairly certain they take over some functions of a cell and then use it's DNA as parts to produce copies of itself. It also happens at the... ribosomes? Can anyone verify this?

A virus injects the host cell with its DNA, then combines with the hosts' DNA. Then it just sits there, being duplicated every time the host cell(s) divides, multiplying in number until a certain condition, like a pressure applied upon the host cell, urges the host to start manufacturing copies of itself, then break out of the host.
The virus is a good example of harmless addition to DNA material (well, except for the taking charge of and breaking out of the host cell), because when it combines with the host's DNA, it doesn't affect the hosts' DNA because it is a complete DNA code and doesn't cause a frameshift.

I have been watching the conversation idly, but just to point out, no it isn't. They are all "theories" in the same sense that they have yet to be disproved (which is what I hope you meant), but evolution certainly has much less experimental evidence supporting it than the other things you've mentioned there. Not all scientific theories are equal.

It's a theory as in it is an extremely well-supported and well-documented scientific explanation for phenomena in the observable universe. Again, a theory in science doesn't mean "a guess" or "something put out there until something better comes up." It isn't waiting to become a proof or a law (the former which exists only in mathematics and the latter refers to a completely different idea in the scientific method). You almost seem to imply that evolution is closer to a hypothesis than a scientific theory. In the scientific community, there is no controversy to evolution. As for your comment about evolution having inadequate experimental evidence, do you have any reliable sources to back that statement up with?

What do you mean "again"? Do you believe you've addressed me at some point previously? I know full well what a scientific theory is. Since you seemingly missed it:


That is the most important part of the definition for scientific theory. Feel free to look it up.


Uh, seriously? I just dropped a pen on the floor. Hey, more experimental evidence of gravity.