mutations arise from insertions of nucleotides, excision of one or more nucleotides, inversion of a strip of nucleotides, replacement of one or more nucleotides, and several other things. Since DNA transcribes into RNA and then into proteins at ribosomes, mutations causing the wrong amino acids than were intended to be a part of the proteins are generally a bad thing.
[/quote]No they generally don't do anything.
from the website...
[quote]Most mutations are neutral. Nachman and Crowell estimate around 3 deleterious mutations out of 175 per generation in humans (2000). Of those that have significant effect, most are harmful, but the fraction which are beneficial is higher than usually though. An experiment with E. coli found that about 1 in 150 newly arising mutations and 1 in 10 functional mutations are beneficial (Perfeito et al. 2007).
I think I have acknowledged that due to the fact that a lot of the mutations that arise happen in non-coding areas they don't matter.
this is how proteins are formed for those that don't know. The transcribed RNA is taken to ribosomes where it is translate into proteins... basically for each codon there is a corresponding amino acid. there are more than one codon for some amino acids... in this way some mutations don't cause a problem... but if they do code for a different amino acid then it messes with the protein it is a part of... and this is how. proteins at the primary level are just a string... or interacting strings... of amino acids. these amino acids have different characteristics. some are polar, some are of neutral charge, some are acidic, some are basic...etc. These different AA characteristics interact with other AA's and form bonds. According to how the bonds are formed and how the amino acids interact, the peptide chain, or protein, folds in on itself and makes a globular quaternary structure. The functioning areas of the protein are dependent on the shape of the protein
protein structure are broken down into primary, secondary, tertiary, and quaternary parts... the primary one may actually just be the individual AA's and their bonds and the secondary one might be the chain but the designation is irrelevant to my point.
if the wrong amino acid is made then it has the potential to completely denature the protein that is supposed to be made. basically meaning it won't work. If its just a problem with the ribosome then it doesn't matter. the messed up protein will be destroyed by a lysosome or some other organelle. if it is due to a mutation in the dna then that problem will happen every time that part of the chromosome is transcribed. if it just happens in one cell then that cell will, if the problem is lethal, die. If it isn't then something might happen and the cell might reproduce wildly... if the cell's tumor inhibitting area of DNA is tampered with or turned off... sounds odd but its true.
its possible that a mutation will insert an amino acid that actually is better than the one intended... hence beneficial mutations.
as seen from the posted website... most significant mutations are harmful... while more than previously thought are beneficial.
this was slightly off topic and a condensed version of an entire chapter out of a book (sorries for the poor conversion from memory)
but I felt I needed to defend my previous statement.
and another thing... although similar... e coli do not have the same replicatory DNA polymerases that are found in humans. the web document... although highly similar to humans can't be seen as something worth going by for humans or other types of organisms. e coli is prokaryotic... prokaryotes account for most bacteria if i remember correctly. humans and lots of other organisms are eukaryotic. I'm pretty sure that there are differences in the fidelity rates in DNA replication of both types of organisms
i mean it probably makes little to no difference because of the scale of the numbers, but there are those out there that think DNA from all organisms is replicated and done the same way in all organisms... the base pairs (adenine, guanine, cytosine, and thymine) are universal, but the enzymes for the different types of organisms are different and can't be used to explain organisms of a different type accurately enough to state such postulations resolutely.
