Question: What gives a DNA its unique properties?

[Shams al-Ma'rifa]

Hey guys, I have a question that has been bugging me for a very long time. I never found out the answer to it so I was hoping one of the more science-minded people on these forums might give me a good explanation.

The question is quite simple really; what gives a DNA its unique properties? It's intriguing to me because DNA by itself is just a simple acid yet it can completely rearrange itself and give rise to life. It fascinates me that a non-living entity, like a virus, which is basically DNA in a protein coat, can function like evil robots and and actually kill you. Furthermore these things can actually mutate when an organism develops resistance to it.

This behavior is all dictated by DNA. You never see any other chemical behaving this way, it seems to actually have a mind of its own.

Can anyone please explains why DNA actually behaves in such a way. What sort of chemical processes occur within a molecule of DNA which gives it this unique "mind" which no other chemicals possess. Thank you

[Clibby]

This is one heck of a question that geneticists are still trying to answer.

First, you do see other compounds behave like DNA. There are viruses out there that contain only RNA and can reprogram cells to replicate them. The only reason viruses are not considered living is because they cannot reproduce on their own nor can they create/find their own food.

I guess the easiest way to understand it is that the DNA is just a code spelled out with those nucleic acids: adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T). A very small code may look something like this: ATTGGAGTACCCTCAGCTTCAGAAATTAATTAA. Alone, it could do nothing. However when certain proteins read that code, they can use it as a template to make RNA. (Very similar to DNA, but slightly different compound. RNA doesn't use T, instead it has uracil (U). RNA is less stable than DNA and can mutate easier, but will not interfere with the DNA). These RNA strands do not copy the entire DNA strand, only the parts the DNA lets it. (DNA has start and stop points for the RNA creating proteins.) This is possible because the two strands of DNA are weakly held together by something known as a hydrogen bond (same thing that holds water together in a droplet). These strands of RNA are then used by ribosomes in the cell (ribosomes are a type of protein) to make new proteins. It is these proteins that make things happen in the cell. Various outside influences can determine which RNA strand is made at any given moment. Cells have numerous receptors for those stimuli that cause a chain reaction leading to the production of proteins that help the cell to adapt to changes.

So the DNA doesn't have a "mind of its own." It provides the framework for all the other interactions to happen, most of which are influenced by factors outside the cell.

If you want to know more, you will need to do some serious research. Wikipedia has a decent intro article : http://en.wikipedia.org/wiki/DNA

However if you are really interested, you will need to take many, many courses at a university. I hope this helped somewhat, but your question has very complex answers.

[Sphere]

Its just a historical legacy that DNA as we know it is used as the information backbone for life on earth. I cant remember who exactly, it was either Francis Crick or Paul Nyren that developed a theoretical "DNA" using different amino acid groups that would be more efficient than DNA as we know it.

That being said, Richard Dawkins has an unsupported preposition which I think is probably correct, that if there is life outside of Earth it will have something like DNA.

[mp0295]

That being said, Richard Dawkins has an unsupported preposition which I think is probably correct, that if there is life outside of Earth it will have something like DNA.

As in some genetic material with repeating sequences. I highly doubt it will be exactly DNA

[Sphere]

As in some genetic material with repeating sequences. I highly doubt it will be exactly DNA

He uses the term the same properties of DNA, so yes you are correct. Though given our understanding of chemistry that does somewhat narrow down the possible molecular makeup, I.e. carbon or perhaps silicon based. Carbon and silicon have the same valence electron shells which give them their unique properties, and the next element in the carbon column, Germanium, is getting just too rare/heavy, indeed heavier than Iron, to be feasible.

[Clibby]

Carbon and silicon have the same valence electron shells which give them their unique properties, and the next element in the carbon column, Germanium, is getting just too rare/heavy, indeed heavier than Iron, to be feasible.

Too rare on earth. All weight is relative. If an organism were to exist on a much larger planet with a stronger force of gravity, then germanium would not seem to heavy. It would have its own problems in terms of size, but I cannot rule out its use elsewhere in the galaxy. We know so little about life that I could not make any concrete conclusions about life elsewhere in the universe. I mean look what NASA did in California. They were able to create a bacterium that incorporated arsenic into its DNA. Who would have thought of that?

[Sphere]

Too rare on earth. All weight is relative. If an organism were to exist on a much larger planet with a stronger force of gravity, then germanium would not seem to heavy. It would have its own problems in terms of size, but I cannot rule out its use elsewhere in the galaxy. We know so little about life that I could not make any concrete conclusions about life elsewhere in the universe. I mean look what NASA did in California. They were able to create a bacterium that incorporated arsenic into its DNA. Who would have thought of that?

By heavy I simply meant the number of protons. The more protons something has the less of it is created in a dying star and therefor the less of it there is in the universe as a whole.

[SoggyFrog]

It's not just the fact that it's a code, it's the fact that it's a self-replicating code. DNA strands are composed of nucleotides, each of these has one of four bases: guanine, thymine, adenine, or cytosine. What gives DNA its function is that each of those bases has a complementary base; guanine matches with cytosine, thymine with adenine. Lone nucleotides can just match up with their complementary nucleotides in an existing DNA strand to produce a complementary strand, although in an actual cell the process would be mediated by a number of enzymes.

However when certain proteins read that code, they can use it as a template to make RNA.

I'm not sure Clibby explained it correctly. Enzymes (proteins) are involved in the replication of DNA in living organisms, but the ability to self-replicate that makes DNA key to life is inherent in the DNA itself. If you just throw a bunch of complementary single nucleotides into water, they will form a double helix composed of two complementary strands as that is the lowest energy configuration possible.

If the following confuses you, just ignore it, it's a bit of an aside to clarify... Because enzymes have to prepare DNA for reading or replication, they do have sections that bind/are attracted to particular lengths of DNA code. However, the actual reading of the code that makes the whole of the RNA molecule is "done" by the RNA nucleotides themselves.

[Dr. Oza]

Some would say that is is Phosphorus and its ability to hold the helix together and such things, but arsenic-based pseudo DNA has been found.

Honestly, this is a question most scientists don't even bother answering, its not so much the why as the how, and the how is understood but we can never know the why. Most likely, as with evolution, there is no why. DNA arose sometime after protobionts and there is evidence that life originally consisted of RNA-based lifeforms, RNA is basically a simpler version of DNA, with the discovery of large macro-viruses , there is also a hypothesis that the earliest lifeforms (chemicals enclosed in membranes, or something of the sort,) were infected with proto-viruses which is how and why we have RNA-DNA.

Sidney Fox and Alexandr Ogarin found that Proto-Bionts, which like i said, are defined as "aggregates of abiotically produced organic molecules surrounded by a membrane or a membrane-like structure," and were the precursors of prokaryotes, can be formed spontaenouslly in conditions similar to a young earth, (a young earth had a reducing atmosphere which acted to facilitate chemical formation) and Ugrey-Miller proved that many of the chemicals: acids, lipids, etc, that were present in these proto-bionts could be formed in dust clouds in space and were found on asteroids (though this is not thought to amount to a significant %)

So basically, chemicals were in an environment where they could form into acids and fats and such things (randomly) and began to form membranes around themselves (why?, we dont know) and RNA which is also basically an acid and could also be formed as the acids and fats were somehow was trapped in these membranes (or had formed membranes of its own(like viruses) and "infected" the proto-bionts) and through billions of years of evolution, these early pseudo lifeforms began to specialize and grow more complex in order to thrive and grow in their environments. Life itself was not really possible until heritable informations (RNA or later, DNA) could be transmitted, you could say that these earliest of "life-forms" were like viruses, not alive, but kinda alive.

DNA in its current form is a conservative system, it does not allow rapid mutation (relatively) and in eukaryotes not rapid at all. Thats because much of the essential framework of life, cellular respiration and metabolic controls, evolved rather rapidly after the proto-bionts.

[Shams al-Ma'rifa]

I'm more interested in DNA and how it relates to consciousness. When you bacteria moving around under the microscopic, are their actions triggered by an unconscious programming (like robots) or conscious thought (like humans). Supposedly, its actions are triggered by certain parameters which determine the most efficient way to gather energy, etc, and that the actions of these organisms are mechanically triggered by these parameters. It's fascinating to see these robotic creatures move in such an organic fashion.

Bees for example, have a certain programming which allows them to solve this mathematical problem in under a second, while it takes the average supercomputer a few days to find the solution for the same problem: http://en.wikipedia.org/wiki/Travell...lesman_problem

It's amazing to me that an unconscious entity such as nature could create biological super robots and even sentient creatures out of a random pile of chemicals. Evolution is the most beautiful concept in the universe, not just the actual nature of it but the philosophical subtext behind it.

[SoggyFrog]

It's an interesting idea, and there's no authoritative answer on where consciousness emerges, but I don't think that you can assign it to DNA. It's a molecule that follows very clear, automatic rules, and its role in the higher functions of an organism is facultative, not direct. Everything that DNA is directly responsible for is at such a small scale and what you would consider involuntary, but beyond even that, processes that you cannot be consciously aware of in your own body except for being told that they are there. Consciousness emerges at some level of the nervous system, at which point you're talking about groups of cells.

Yes, DNA and the way that it is read is responsive to changes in the environment, whether in unicellular or multicellular organisms, but these changes are themselves programmed in the code of DNA. So within an organism, considering a particular length of DNA, it does not actually act or adjust itself to what is going on, even if these epigenetic responses are present they are also in a way part of that existing piece of DNA. The behaviour of your nonsentient bacteria or your sentient human comes from all the proteins that have been created by the DNA and all of the cell components they eventually manufacture as enzymes. The DNA itself changes only through generations undergoing evolution (though it's a bit more complicated considering bacterial genetic exchange and the like). Evolution is definitely amazing, but it and DNA are entirely unconscious.

It's not because DNA wants to replicate itself that it thrives, it's that DNA whose properties will lead to its replication does thrive.

[Plant]

There's no reason why conscious thought is not simpy an illusion of unconscious programming. In fact, it's beginning to look that way.

[Helm]

According to Pastafarianism the FSM when he was designing life on Earth came up with the idea for the helix structure of DNA based on rotoni pasta.



It behaves in a unique way because he is constantly touching the structures with his noodly appendages, so it's all linked together within the cosmic order.

[SoggyFrog]

Moreover, there are many notable instances...* where interdomain transfer has clearly resulted in the displacement of an isofunctional enzyme.

*The citation here was, 'W.F. Doolittle and J.M. Logsdon Jr., Curr. Biol. 8, R209 (1998); M. Ibba, J.L. Bono, P.A. Rosa, D. Soll, Proc. Natl. Acad. Sci. U.S.A. 94,14383(1997).'

In layman's terms, a gene belonging to an organism in one domain (bacteria) somehow° entered the genome of an organism in another domain (archaea), then drove the equivalent gene in that archaea species to extinction, while the species of archaea itself remained.

If that doesn't seem to make any kind of sense, you can reinterpret it as the descendents of an archaea that gained the gene outcompeting related archaea, then another archaea losing the archaeal gene and outcompeting related archaea. I don't know if that accurately describes the sequence of events, but it's easier to understand if you think about it that way.

However, you don't have to think about it in that conservative way I just described; it's fascinating to think about organisms only being incidental in terms of pieces of DNA competing with other pieces of DNA. This is an extreme example because the gene was established in the second organism long after the two species' ancestors diverged.

° There's a number of ways that this - the process is called lateral gene transfer - can happen.

[Cannibalking]

Unique compared to what?

I think part of the answer is Polymerase and replication.

Because of how easy DNA replicates compared to other molecular structures, it can have large amounts. Thanks to PCR(PRC? Can't remember) we can speed up DNA replication.

I think the reason it can adapt and/or change is because of its fast replication. Also, DNA and Polymerase both has a strong resistance to heat. Most heat DESTROYS protein structures, but not Polymerase or DNA.

As for what the deoxyribose sugar has to do with helping/or increasing adaptability compared to RNA I do not know.