How is it an amoeba can have 200 times the DNA a human has ?

[dr.syntax]

How is it that an Amoeba has 200 times the DNA of a human ? An onion 12 times as much. A rasberry has 12% of the DNA of a human wich seems logical. It`s a simpler organism and would require less DNA to produce the fewer attributes to be expressed. As far as I know ,no one has come up with a cohesive answer yet. If someone did I did not read of it. The Harvard Gazette is where I got the figures used here. There is speculation out there but no decisive answers. I appears to me amoebas have simply been piling up random DNA that occurred through mutation as long as it did not prove fatal or detrimental to it`s survival over the 2 billion year history of thier existance. No delete function or unesessary files clean up function and have continued to carry about a massive ammount of DNA that serves no purpose. I`ve read articles stating about 95% of human DNA is junk. Anyone else have any thoughts , information on this they`d like to share ? ...Dr.Syntax...... Post Script: eukaryotes generally do have manitudes more DNA than prokaryotes. Total DNA content is known as C-value. Humans do have more genes than amoebas. This massive discrepency between human DNA to amoeba DNA content is NOT confined to amoebas and is known as the C-value paradox. The energy required to store and replicate this DNA in Amoebas is massive and slows the replication process significantly. I`m getting all this information from: " Power Sex suicide: mitochondria and the meaning of life". Written by Nick Lane. The link I found is ridiculously long and those long type never work for me any way. ...ds

Edited September 28, 2009 by dr.syntax

[insane_alien]

another question would be why should we expect it to have less?

 

all it means is that it never encounteredselection pressures that favoured it having a reduced genome.

 

infact, it is highly plausible that there were selection pressures favouring a large genome. such as increased mutation rates(could be from a variety of sources, chemical/radiation etc.).

[JillSwift]

A rasberry has 12% of the DNA of a human wich seems logical.

That statement is the core of your problem understanding this stuff.

 

Nature is under no requirement to meet our ideas of what is logical. All life is doing is existing within the parameters that allow it to exist. (That is, the only reason life does not exist outside those parameters is because it's impossible.)

 

One of the most fascinating aspects of the cosmos as a whole, and DNA in particular, is emergence. The "information" in a strand of DNA is not simply the pattern of nucleotides, but how each part interacts with the other parts. In this way an allele can be lost, and a phenotype gained. Also, if you look at DNA more as a "recipie" for an organism, you can see how environment plays a more direct role on individual organisms. For instance, height is a trait that sees an 85% inheritance in groups with constant good nutrition and health care, while seeing only 60% in groups with variable access to nutrition and health care.

 

Hope this helps.

[dr.syntax]

That statement is the core of your problem understanding this stuff.

 

Nature is under no requirement to meet our ideas of what is logical. All life is doing is existing within the parameters that allow it to exist. (That is, the only reason life does not exist outside those parameters is because it's impossible.)

 

One of the most fascinating aspects of the cosmos as a whole, and DNA in particular, is emergence. The "information" in a strand of DNA is not simply the pattern of nucleotides, but how each part interacts with the other parts. In this way an allele can be lost, and a phenotype gained. Also, if you look at DNA more as a "recipie" for an organism, you can see how environment plays a more direct role on individual organisms. For instance, height is a trait that sees an 85% inheritance in groups with constant good nutrition and health care, while seeing only 60% in groups with variable access to nutrition and health care.

 

Hope this helps.

 

Reply: There is a tremondous energy cost to the amoebas. The massive amount of DNA required of them not only to carry around with them but more importantly the replication of such massive amounts of DNA and the energy and time required for this task plus an additional task of maintaining exact copies of all this information would seem to create a serious natural selection downside.This is called the C-value paradox. Was it really necessary for you to start your reply to me with :"That statement is the core of your problem understanding this stuff". What statement are you refering to ? Why is it you find it necessary to begin this new thread by once again belittling me ? It is not me who gets this stuff started. Try refraining and I will do the same. ...Dr.Syntax

Edited September 27, 2009 by dr.syntax

[JillSwift]

Reply: There is a tremondous energy cost to the amoebas. The massive amount of DNA required of them not only to carry around with them but more importantly the replication of such massive amounts of DNA and the energy and time required for this task plus an additional task of maintaining exact copies of all this information would seem to create a serious natural selection downside.

As I said, nature is under no obligation to make sense.

 

The bottom line is, the situation works. It does not have to be optimal, it just has to work.

 

Was it really necessary for you to start your reply to me with :"That statement is the core of your problem understanding this stuff". What statement are you refering to ? Why is it you find it necessary to begin this new thread by once again belittling me ? It is not me who gets this stuff started. Try refraining and I will do the same. ...Dr.Syntax

Yes, it was necessary. You aren't grasping some concepts and I was pointing out a possible reason why.

It was an attempt to help.

 

The statement was the one I quoted - that statement assumed that your logic was being ignored by nature. Which is a problematic viewpoint.

 

It was not an attempt to belittle you. It was not personal in nature. Stop assuming you are under attack, it's really gettin' annoyin'.

[mooeypoo]

Dr Syntax, if you intend to stay in this forum, you have to stop being so defensive. You asked a question and people are trying to help you. Pointing out where your logic may be flawed is PART of answering you.

 

If you intend on being defensive and claiming everyone's out to get you, maybe you shouldn't post here at all.

 

Maybe you shouldn't deal with science at all, either, seeing as this community is nice and cuddly compared to a true peer review process.

 

~moo

[iNow]

[CharonY]

This depiction is rather unrealistic. At least unless the paper accepted sign is actually a concealed trap.

[JillSwift]

Naturally, CharonY. It's what you don't see that should worry you.

[CharonY]

You mean the tar pit between the chain saw guy and the axe lady? I saw that from a mile away.

[JillSwift]

You mean the tar pit between the chain saw guy and the axe lady? I saw that from a mile away.

Yeh sure, rub your experience with peer review in muh face

 

That would have gotten me, I thought it was just shiny pavement.

[Sisyphus]

Um, anyway. Some thoughts:

 

1) You're still stuck on thinking of humans as the most complex organisms. Until you realize that's not true (or only true according to one highly specific definition), I predict a lot of things aren't going to make sense. Stop thinking anthropocentrically!

 

2) Clearly (right?) there's a lot more variation in amoebas than in humans, though most of it isn't immediately obvious.

 

3) The amoeba in question is one giant cell (giant for a cell, that is), and all metabolic function has to be controlled somehow.

 

4) It seems like more DNA would mean more mutation, which would mean faster (and better?) adaptation to changing circumstances.

 

5) Amoebas are, in a sense, a whole lot "more evolved" than us, because they've had so many more generations since our common ancestor in which to evolve.

 

6) Amoebas are wildly successful, evolutionarily speaking. Large animals like us come and go, but they were here long before us and they'll be here long after us, and they vastly outnumber us.

[bascule]

Natural selection, being a process that finds solutions "by accident", doesn't have the advantage of finding the minimal amount of nucleotides to represent a particular organism. However many it takes is what it ends up with.

[dr.syntax]

Dr Syntax, if you intend to stay in this forum, you have to stop being so defensive. You asked a question and people are trying to help you. Pointing out where your logic may be flawed is PART of answering you.

 

If you intend on being defensive and claiming everyone's out to get you, maybe you shouldn't post here at all.

 

Maybe you shouldn't deal with science at all, either, seeing as this community is nice and cuddly compared to a true peer review process.

 

~moo

 

Response: stick with scientific arguments ,don`t make personal attacks. Look at what is being directed toward me. The ridicule and such. Are these scientific arguments? I made some mild comment to someone about not belittling me and you start to threaten me again with expulsion. This new thread I started has become a place for many people to heap abuse upon me once again and I am not allowed to defend myself . Many of you make me unhappy . What a bunch of neurotic egomaniacs some of you are and how very well you all stick together and support each other. The only peer review going on around here is with some of the newer guys. The rest you spend all your time sucking up with each other. Whatever ...Dr.Syntax

Edited September 28, 2009 by dr.syntax

[mooeypoo]

Response: stick with scientific arguments ,don`t make personal attacks. Look at what is being directed toward me. The ridicule and such. Are these scientific arguments? I made some mild comment to someone about not belittling me and you start to threaten me again with expulsion. This new thread I started has become in a place for many people to heap abuse on me once again and I am not allowed to defend myself . many of you make me unhappy . What a bunch of neurotic egomaniacs some of you are and how well you all stick together and support each other. The only peer review going on is with some new guy. The rest you spend all your time sucking up to each other. Whatever ...Dr.Syntax

Stop looking at what others do, and start making sure YOU are following our rules, dr syntax.

 

I have no patience to argue with you about how to enforce the rules. If and when I see something inappropriate, the moderators respond. You have a button on top of each post with a red triangle you can click and REPORT A POST. That brings it to the moderators' attention, and we deal with it.

 

This isn't YOUR forum, and these arent YOUR rules. I will not argue with you abotu how to enforce OUR rules.

 

Everyone is being very patient so far with your continuous insistance to avoid giving evidence to your claims. Instead of arguing science, you resort to calling everyone else bullies, when all they do is call you out on the FACT that you have no evidence.

 

This is the bottom line: You have no evidence, and yet you argue as if you do. People call you out on it, because that how scientific arguments are done. Instead of coming back with a scientific argument, you're whining about your treatment.

 

If you cannot handle criticism, don't post in a forum. Any forum, for that matter, not just ours, because you're going to get criticism everywhere.

 

We're not here to cuddle you, we're here to debate, and you're not making our lives any easier by avoiding answers. No one cursed, no one bullied, no one called you names. People stated - justly so - that your evidence are nonexistent.

 

Grow up. Start debating like an adult, follow our rules, and stop being so defensive. Not everyone who criticizes your post is out to get you.

 

We have better things to do. Seriously.

 

~moo

[dr.syntax]

Um, anyway. Some thoughts:

 

1) You're still stuck on thinking of humans as the most complex organisms. Until you realize that's not true (or only true according to one highly specific definition), I predict a lot of things aren't going to make sense. Stop thinking anthropocentrically!

 

2) Clearly (right?) there's a lot more variation in amoebas than in humans, though most of it isn't immediately obvious.

 

3) The amoeba in question is one giant cell (giant for a cell, that is), and all metabolic function has to be controlled somehow.

 

4) It seems like more DNA would mean more mutation, which would mean faster (and better?) adaptation to changing circumstances.

 

5) Amoebas are, in a sense, a whole lot "more evolved" than us, because they've had so many more generations since our common ancestor in which to evolve.

 

6) Amoebas are wildly successful, evolutionarily speaking. Large animals like us come and go, but they were here long before us and they'll be here long after us, and they vastly outnumber us.

 

Wrong,I never said I thought of humans as the most complex organisms, I went so far as to suggest porposes,whales,and elepants where equally if not more complex.Also,large animals like us do not always come and go. Sharks have been around for 400 million years. For what it`s worth,you are the one who got me interested in all this. At least I now know what to call it, the: C-value paradox. ...Dr.Syntax

Edited September 28, 2009 by dr.syntax

[Mokele]

A key thing to remember is that, while copying more base pairs costs more energy and more nutrients, energy and nutrients aren't always the most important thing.

 

All other things being equal, organisms will try to economize, but all other things are almost never equal. Consider the energetic penalties of sexual ornamentation, or being built for high speed (which often requires a high basal metabolic rate too, reducing even resting energy expenditure).

 

Furthermore, organisms can add DNA rapidly (anueroploidy, whole genome duplication, etc.), but loss of DNA isn't nearly so fast - dropping a whole chromosome might cause problems during meiosis for sexual organisms, so they have to lose it by little bits.

 

Last but not least, whole genome duplication often results in physical transformation - polyploids are often larger, stronger, more resistant to disease, etc. which is why so many common crops are polyploid. In a species where size may have definite advantages (a frog that can lay more eggs, an amoeba that can eat bigger things), the benefits of keeping the extra DNA may outweigh the costs.

[Mr Skeptic]

Compare the computer programs of decades past with those of today. Back in the day, computer programs fit on punch cards and later diskettes. Now no one bats an eye at programs thousands of times bigger. Have the computer programs become thousands of times better? No, simply the need to carefully economize on program size has nearly vanished due to new technology, and instead we revert to economizing on programmer's time.

 

Likewise, if the selection pressures don't require compact DNA, you can expect the genome size to expand. Because eukaryotes have a far quicker DNA replication method (replicate at multiple sites) and also slower replication cycles, we don't have nearly the selection pressure prokaryotes to minimize DNA.

 

Another thing to consider: you say an amoeba is less complex than a human. Consider, however, whether an amoeba is more or less complex than a human cell? Do human cells live in a more or less dangerous environment than amoeba cells, and do they have more or less tasks to do?

[dr.syntax]

Compare the computer programs of decades past with those of today. Back in the day, computer programs fit on punch cards and later diskettes. Now no one bats an eye at programs thousands of times bigger. Have the computer programs become thousands of times better? No, simply the need to carefully economize on program size has nearly vanished due to new technology, and instead we revert to economizing on programmer's time.

 

Likewise, if the selection pressures don't require compact DNA, you can expect the genome size to expand. Because eukaryotes have a far quicker DNA replication method (replicate at multiple sites) and also slower replication cycles, we don't have nearly the selection pressure prokaryotes to minimize DNA.

 

Another thing to consider: you say an amoeba is less complex than a human. Consider, however, whether an amoeba is more or less complex than a human cell? Do human cells live in a more or less dangerous environment than amoeba cells, and do they have more or less tasks to do?

 

REPLY: Hello Mr. Skeptic, you made some good points. I have read some others thoughts on the subject known as the: C-value paradox. It is a very complex topic and many scientists have thought about it. I am not at all sure the complete and final answer is in at this time. There is no clear pattern that I see. A plant such as an onion can have 12 times as much DNA as a human and another plant, a rasberry can have but 12% of the DNA of a human. A frog has about 2.3 times as much DNA as a human. I`ve been looking for a chart showing different C-values [ DNA counts ] for a wide range of organisms and have not yet found one. Oh Well, ...Dr.Syntax

[StringJunky]

Dr Syntax: Is this what you are looking for?

 

http://www.genomenewsnetwork.org/articles/02_01/Sizing_genomes.shtml

 

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GenomeSizes.html

[dr.syntax]

Dr Syntax: Is this what you are looking for?

 

http://www.genomenewsnetwork.org/articles/02_01/Sizing_genomes.shtml

 

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GenomeSizes.html

 

Thank You my friend. I printed them up. I appreciate it very much. ...Dr.Syntax

[Sisyphus]

Wrong,I never said I thought of humans as the most complex organisms, I went so far as to suggest porposes,whales,and elepants where equally if not more complex.Also,large animals like us do not always come and go. Sharks have been around for 400 million years. For what it`s worth,you are the one who got me interested in all this. At least I now know what to call it, the: C-value paradox. ...Dr.Syntax

 

Fair enough. Still, why the assumption that animals are inherently more complex than plants? Plants can be bigger than us, they've been around longer, they vastly outnumber us, they can survive just fine without us but we can't survive without them, etc. I don't know enough about it, myself, but from what I gather from botanists, plants in general are actually much more sophisticated in a lot of ways than animals. Although I suppose a botanist would be biased, and, as has been said a lot, there is no objective measure of complexity or sophistication.

[Mr Skeptic]

I would like to point out that a lot of the complexity in us animals actually exists in the nervous system, rather than having a genetic basis. For example, the genetic information of a human fits on a CD. But how much information is stored in the nervous system? I would wager we have amoebas beat in that sense. At the cellular level, though, human cells are not at all impressive.

[Sisyphus]

I would like to point out that a lot of the complexity in us animals actually exists in the nervous system, rather than having a genetic basis. For example, the genetic information of a human fits on a CD. But how much information is stored in the nervous system? I would wager we have amoebas beat in that sense. At the cellular level, though, human cells are not at all impressive.

 

That's at least superficially true. But then, where does the complexity of the nervous system come from? It's a pattern emerging from the "rules" dictated by the genome. So in a sense the complexity is already there, just in "compressed format." While in a single-celled organism, I guess everything is expressed all the time, and the genome has to do things that in a multi-celled organism would be done by emergent macrostructures?

[PhDP]

First of all, if you're looking for the C-value of several organisms, there are entire databases devoted to this;

 

Animals: http://www.genomesize.com/

 

Plants: http://data.kew.org/cvalues/homepage.html

 

...

 

The term "C-value paradox" is quite misleading, "C-value enigma" makes more sense. It's not a paradox in the sense that we very well know what mechanisms could generate such pattern. It was a paradox only until we discovered that so much DNA is noncoding, "junk". In short, again, if the concept of C-value and junk DNA are so difficult to understand for some people, it's because they are either convinced natural selection is the main driving force of evolution, or, even worst, they think it's the only one.

 

Now, the C-value enigma is not to be solved with a simple answer, there are too many things going on inside the genome; some groups have more transposable elements than others, some groups are more likely to experience whole-genome duplication, some selective pressure seem to keep the genome small in some group with high energy demands (like: flying organisms) and genome size also has an impact on the phenotype (cell size, development rates...), so negative selection is certainly not out of the picture...

 

You're certainly not going to get any good answer to your question here, the various solutions to the C-value enigma are currently actively debated, you would likely not even get the same answer from two scientists working on the subject. Still, if you want to study the question further, I suggest Gregory's "onion test" (http://www.scientificblogging.com/genomicron/junk_dna_and_the_onion_test), it's a nice, well-written article, and "the evolution of the genome" (a book edited by Gregory). He's specialized in the genome size debate, and he's also a skilled science popularizer.