Mutation Balance: Lost Traits & Complicated Species

[binbots]

If a organism has a dna mutation, would this not imply that some trait is lost. If there is a mutation then somewhere in the dna there is a difference which would cause something to be missing. Is this right? If this is the case then how come complicated speices still have all there original DNA. Are the DNA mutations some sort of extra DNA? thanks

 

[zhermes]

I think the best answer to your question is 'yes.' Most mutations are "deleterious," they cause a loss/decrease in normal abilities. However there are lots of other things to consider:

In humans (and similar organisms), most DNA is "non-coding" DNA, and the purpose it serves is largely unknown (although there are many reasons to think it does serve numerous purposes). Mutations in this type of DNA, has little or no effect.

Additionally, single mutations even in DNA that is "coding" is often not enough to have a significant effect: i.e. i may make a protein a little worse at what it normally does, but it might still work.

No species has all of its 'original' DNA.

 

[Skrambles]

There are several different types of mutations or changes that can occur in DNA. A single base or letter may change or whole segments may even be copied many times in several locations.

http://en.wikipedia.org/wiki/Mutation

The single base change, or point mutation, is likely not going to make much difference. The coding sequences are highly redundant, so more than one three-base set represents each amino acid. A point mutation may not change the protein in any way, and if it does manage to change one amino acid it may not change the shape of the protein in the end.

There are also chemical changes that alter the way DNA is expressed without changing the code.

http://en.wikipedia.org/wiki/Epigenetics

"Non-coding" parts of DNA do indeed seem to serve a purpose by coding for microRNA molecules that can regulate protein production and expression.

http://en.wikipedia.org/wiki/Micro_Rna