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DNA strand lengths?

Discussion of everything related to the Theory of Evolution.

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DNA strand lengths?

Postby Kukagra » Wed Sep 15, 2010 8:46 am

Okay, I my question is if the human if the length of a human Genome is a specific number of base pairs and that length is the same for all humans but the genome differs in lengths from one organism to another then is that length changing? Because if it did then the theory of evolution could be true because we could see the length changing from one generation to another. Now if an organism has had generations then the longer it Genome should be. If the length of the Genome changes then that would explain changes in Evolution of that organism it picks up those traits while adding new genes. So, do Genomes stay the same length or get longer and shorter.
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Postby Kukagra » Wed Sep 22, 2010 7:48 am

For anyone who cares I found an answer from a Dr. that teaches at a local Community College.
"We do know that among bacteria, the genome size varies from genus to genus. For example, E. coli has ~4 million base pairs, whereas P. aeruginosa has ~6.3 million base pairs. Which species came first is speculative. Size appears to be only one of many ways to derive an evolutionary ladder.

How have organisms like P. aeruginosa acquired additional bases? We know that by acquiring plasmids via conjugation, some genes of the plasmid or the entire plasmid can integrate into the chromosome. Another way is by viruses infecting the cell, and then inserting their DNA into the bacterial chromosome. We know that HIV, HPV and a few others will do this after they have invaded a human cell as well. And one other mechanism called transformation allows some species to take up DNA from the environment. Finally, and this applies to humans as well, there are genetic sequences which have the ability to duplicate themselves. Thus, bacteria can gain new genetic material or duplicate existing DNA and thus increase their genome size. In the process, a new species may develop. But again, is the increase seen along a time line, with the size increasing as time passes.

Now, does this same process explain the increase in genome size among species seen in the fossil record? I don't know. Should it? Increasing complexity suggests it should."

Now this is not me saying this this information comes from Dr. Gaeddert
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Re: DNA strand lengths?

Postby JackBean » Wed Sep 22, 2010 10:43 am

Well, for the lower organisms (like from viruses to low vertebrates/plants), there is kind of correlation between genome size and the organism complexity as seen here:
Image
credit
(not the picture I was looking for, but you can get the idea...)

The size of genome varies between each two organisms, you can have several indels (smaller or even larger, just look to many diseases), even the chromosomes can be rearranged.

And how to gain the extra DNA? Basically as you already said. If we forget about the viruses and transposones and are interested only in coding genes, you can have duplications of some areas of rearrangements of chromosomes, which could lead to gain of extra DNA.
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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