Question on genom...

[camel]

Good morning, I need an answer to the follwoing question:

Why has the lungfish a 30 times longer genome than the mouse?

I am not a biologist anf it will be very helpful if somebody knows.

Thank you very much!

[JackBean]

they can contain many doubled/tripled/... genes, repetites etc.

Our genome is larger than that of mouse too, yet we have approx. the same number of genes.

[Jillo725]

possibly because lungfish has been around for a much longer time than mammals and therefore had a much longer time to accumulate transposons and other "extra" DNA that has become incorporated.

[kolean]

Because a lungfish is a different organism than the mouse, and has its own genome. Just like every organism has its own genome, and thus makes them unique for their species.

Why, do you think length/size matters?


in the genotype of the organism that is? Do you think because the lungfishes' genome is 30 times that of a mouse, that the lungfish is 30X more complex (and perhaps it does have 30X more genes: could be duplicates or multiplicates of the same gene though, or even unique different ones but not functional) than the mouse?

[JackBean]

possibly because lungfish has been around for a much longer time than mammals and therefore had a much longer time to accumulate transposons and other "extra" DNA that has become incorporated.

I think, that mammals are here exactly the same time as other now-living organisms, aren't they? At least in the form of their ancestors. Or always, when someone evolves into new species, he loses all the mess in his genome?

Do you think because the lungfishes' genome is 30 times that of a mouse, that the lungfish is 30X more complex than the mouse?

Well, there is actually some correlation for lower organisms

[camel]

Thank you very much all for your answers They gave me a good idea

(by the way, size does matter , but in a different way...around 80 questions to be answered for a course )

[franzb]

by the way, size does matter

It does! But only sometimes!

[Jillo725]

I think, that mammals are here exactly the same time as other now-living organisms, aren't they? At least in the form of their ancestors. Or always, when someone evolves into new species, he loses all the mess in his genome?

Oh duh! I didn't think about it that way!

[Orome]

Actually It is not known for what purpose the lungfish needs it giant genome. But it was observed that there is a correlation of giant genome size with neoteny in urodeles. Those with the largest genomes are those with the most obligate form of neoteny and the longest history of neoteny within the family.

[kolean]

I do not think that a lungfish 'needs' a giant genome. I think that it is stuck with it. DNA is a very opportunistic biochemical and can utilize alot of functions. Repetitious DNA segments can be added quite easily, and if the epigenetic pattern can bind it up so that it is not utilized by the organism, then it can be replicated and passed on down. More mutations and more transposons can take a repetitious piece of DNA and make it into a psuedogene, and the epigenetic pattern can be mutated so that the psuedogene gets expressed and see how the organism does with that new gene (die off or procreate with a new gene). Also duplications of nonrepetitive DNA segments can also be made into new genes, with the catalytic domain of one and the DNA binding of another. So a lungfish perhaps does not have the DNA repair systems, but has an awesome suppression/epigenetic silencing mechanism, and can pack in the DNA.