random mutation explination help

[gebreab]

Hi I am new, I just had a question on my mind, and after searching google for a while I couldn't find an answer. I was hoping someone on this forum might be able to help.

edit: before you read, i dont mean this to be anti-religion or anti-science, i am not implying anything by my question!

 

So, the question I have is about random mutation. I just don't really understand how a gene can randomly mutate and have new traits? or alleles? however it works??

 

so what has always bothered me is the idea that at one point in our history on earth there were lots of creatures, but none of them had bones. so what i dont get is how through natural selection and random mutation did we end up with bones? my brother always says over time... but what i mean is, how can even the first step toward bones take place? was bones already available in dna but not used? was bones created?

 

i guess the core of my misunderstanding is that how can a mutation in coding(i think) create something that has never existed before? how does it have the knowledge? or how can the code be so powerful that it can create what has never existed?

 

Does this mean that the code or dna can create anything? if it can create bones and muscles and all this stuff then does that mean it can really create anything givin the time? and how can it do this? where does its knowlege come from? or how does the power in the code, mixing the a t g c up exist?

 

do scientist know if dna already had this blueprint already stored up? like potential energy? waiting to be expressed? or did longer codes and more time end up with more creations of complex things.

 

I hope someone can discuss with me because I like the idea of evolution, it makes sense to me. but there are some things that i cant really make sense of. Please lend me your thoughts, Thanks!

[akh]

There is a lot of area to cover here by your questions. The simplest answer is just what your brother said, "over time". You can get a point mutation that can alter a gene or expression of the gene so that there is a very slight phenotypic change. This change may give an individual an advantage, that ultimately realates to greater reproductive success over its peers. As such, this altered gene increases it frequency in a given population. Over time, given enough mutations, new structures emerge.

 

This is a very simplistic view. There is no way to cover much more than the very basics in a thread. This basic info will not be thorough enough to answer all your questions. I suggest that you google search Berkley University History of Evolution. They have a great website set up that explains evolution and answers many of your questions.

 

Sorry, a better search is Berkley Evolution 101. Great resource with other links too. Also look up evolution of the eye and evolution of ears.

[dmaiski]

random mutation is just a blanket term for a lard swathe of not so random events that can happen to your poor abused DNA strands

 

examples of such things are(drum roll)

 

1. mutagens(natural, artificial and biological)

examples: virus, uv light(and everything above it), chemicals, reactive oxygen species, physical damage(hitting your toe with a hammer)

 

2. your own body

examples: DNA replication(its done by proteins that have the copying ability of a 8 year old; atagagg atagagg atacagg atacagg...), DNA repair systems not repairing things so well, wear and tear from all the busy unwinding rewinding transcribing that goes on(fits into DNA repair)

 

3. not so spontaneous events

simply put at the molecular level sometimes "shit happens" and molecular bonds may decide that they would much rather be attached to that sexy little water molecule then the long boring DNA strand and can kind of run off with it(or if your going with the analogy elope) it happens rarely and there is mathematics physics and chemistry that will explain the why, when, where, and how sexy an oxygen attached to 2 hydrogens atoms can be(but i don’t know all those equations and am not writing a 500 page report on it).

 

 

[jp255]

People often ignore the contribution of crossing over/Homologous meiotic recombination to evolution. Which has some useful evolutionary mechanisms which allow for genome changes of varying size (mis-aligned crossing over), exon shuffling (crossing over within a gene), allele shuffling (crossing over outside a gene), and gene conversions (one allele is converted to other form, resulting in two of the same alleles). Recombination itself has tons of different types of recombination mutations within these categories that can lead to gross changes of the genome and alteration of genes/alleles by exon shuffling or partial gene conversion (leads to new allele).

 

 

 

random mutation is just a blanket term for a lard swathe of not so random events that can happen to your poor abused DNA strands

 

It is generally accepted that these are random events in regards to position in the genome at which they occur. Sure they are not random in terms of mutation rate due to chemistry/maths, but position wise they are considered random. There are non-random mutations though, such as crossing over, which is known to occur at hotspots. These hotspots give rise to Linkage disequilibrium. Also hotspot usage (in meiotic recombination) is largely controlled by genetic loci in humans, and varies between populations resulting in the different LD maps in Hap map. Since those Hapmap studies, it has been investigated further and the gene controlling meiotic recombination in humans is PRDM9. I believe this is one of few mutations are considered to be non-random in regards to position.

 

 

 

[gebreab]

hey thanks for helping me figure this out. I will definitely check out that Berkley website, i still have a lot of questions!

Edited September 5, 2012 by gebreab

[Jens]

so what has always bothered me is the idea that at one point in our history on earth there were lots of creatures, but none of them had bones. so what i dont get is how through natural selection and random mutation did we end up with bones? my brother always says over time... but what i mean is, how can even the first step toward bones take place?

 

Bones actually did not start as bones. It started long before there were any animals on land. It started around 800 million years ago when all the different types of animals evolved. There was one type (the predecessor of the fishes, which were predecessors of the amphibia which were predecessors of mamals) which moved more quickly through the water by snake-like movements. Now I give you a hypothetical way of evolution just to illustrate the possibilities: A mutation had as effect that cells around a central axis produced more extracellular structure proteins so that a more rigid axis appeared. Those individuals could actually swim faster and were more successful. On the following generations additional mutations occured so that the cells of the central axis produced even more structure proteins. A next mutation lead to a copy of the structure protein gene, which did not change anything but even more structure protein. A next mutation lead to a situation that the copy was only active in the central axis cells. This specifically increased the structure protein in the central axis cells. This copy changed to become a protein which was much more rigid than the original protein (and let the fishes swim faster). Ultimativly this lead to an axis of cartilage. In some fishes (not in sharks for example) this axis evolved into something even more rigid -- the first bones.

 

Was bones already available in dna but not used?

 

No.

 

Does this mean that the code or dna can create anything?

 

Partially yes: Anything can be created which can be done by proteins or RNA or by chemical substances which can be synthesized by proteins or RNA and which can be reached via intermediate states which are not deadly (lethal) to the organisms.

(nuclear fusion for example is definitely out of reach, or metallic aluminium)

 

where does its knowlege come from? or how does the power in the code, mixing the a t g c up exist?

 

There is no knowledge. The power lies in the proteins coded by the DNA, not in the DNA itself. The sequence of A T G C codes for 20 different amino acids. This means depending on the sequence of the A T G C a protein is produced in the cells that is a sequence of 20 different amino acids. Depending on this exact sequence the proteins form a precise 3D structure. This 3D structure determines which function a protein has. This function can be making a chemical reaction or forming chains to build stable structures (like in the cartilage mentioned above) or other things.

 

do scientist know if dna already had this blueprint already stored up? like potential energy? waiting to be expressed?

 

No. There is no blueprint waiting to be expressed.

 

or did longer codes and more time end up with more creations of complex things.

 

Yes.

 

i guess the core of my misunderstanding is that how can a mutation in coding(i think) create something that has never existed before? how does it have the knowledge? or how can the code be so powerful that it can create what has never existed?

 

Just take as example the immuno response which takes place in every human during his lifetime. This is no evolution in the strict sense, but it is a similar principle: How does the body know to fight against microbes, which did not even exist at time the human individual was born? How can a stupid system of chemicals in the human body distinguish between human cells to be preserved and microbes to be killed? Nobody is designing it. The answer is random production and selection. (I am now simplifying a bit:) During the early months of life cells with many millions of different antibodies are produced by randomly combining different DNA pieces into one gene (of course attached to a fix part, which ensures the antibody function). Each cell produces exactly one variant of antibody. Those cells are all not active yet. They all pass through the thymus. In the thymus there are specific cells which can activate the immuno cells. There are also cells which produce all of the surface proteins of human cells. Any immuno cell binds to one of those cells in the thymus is killed. Only those who do not bind are activated.

 

hope that gives a first insight

Edited October 20, 2012 by Jens