I got into a conversation yesterday about amoebae, in which I confessed to having always been fascinated by these little critters. For one thing, an amoeba multiplies by dividing, which appeals to the punster mathematician in me. For another, all members of an amoeba species have the same genetic makeup. After all, when two amoebae split, they each retain the original DNA.
And this last point leads to another wonderful paradoxical question: Is a species of amoebae a collection of some of the world’s tiniest animals, or is it actually a single geographically distributed individual, which would make it one of the world’s largest individual creatures on earth?
I was inspired by these musings to try to make an animated amoeba. Nothing like the real one, which is all gnarly with weird little textured spots, but rather a sort of cartoon version, an impression of an amoeba to match the not very accurate image of an amoeba that I’ve carried around in my head since I was about seven years old.
In my typical fashion, I made my amoeba friend last night as a Java applet. If you have a Java-enabled Web browser, you can play with it for yourself. It just kind of hangs out in its space, until you drag your mouse near it, and then it tries to chase your mouse cursor.
I have a sort of “amoeba-cam” trained on it, a camera that is always centered on the amoeba. Otherwise it might just ooze right out of the applet frame and devastate the countryside.
You can play with my new little friend here.
Identical Twins also share the same DNA… So, are they just one geographically seperated person? 🙂 A clone, I’d argue, is just a chronologically seperated person.
But, back to the amoeba… Can we do something about this dysentery thing? It’s made so many travelers afraid to drink the water…
Well, actually, identical twins are not genetically identical. There’s definitely a stronger argument to be made in the case of a clone.
Fortunately my java applet amoeba only poses a health threat to travelling java applet people. 😉
From what I understand, identical twins have the same genotype, but, not the same phenotype…
so, the DNA is the same, but the fingerprints are different… you can’t distinguish identical twins with dna tests.
this is based, of course, on online wiki answers, as I am not a professional geneologist. (which of course, would make me Mormon, and we’d be back to the old prop 8 discussion….)
No, identical twins do not have identical DNA. By the way, the Wikipedia article on twins refers to this report on the genetic differences between monozygotic twins.
Like I said, my evidence came from online and unsubstantiated information from simply typing “Do Twins have the same DNA” in google… The first page of articles all said, “yes”. Such as the first one, http://ask.yahoo.com/20010213.html
Being neither a geneologist, nor a dNAtisist, or even a biologist, but, somewhat of an evangalist, I can only base my results on the number one response from my oracle, “Google.com”.
I will read your reference to the misogynistic twins referenced above… It would be really interesting if they were female.
I read your referenced article. It had a lot of “might” “may” and “mostly” but nothing definitive other than the theory that splitting cells may sometimes make mistakes in transferring DNA to their daughters.
The most definative statement in the article was “Now scientists have learned that all identical twins may actually differ genetically”
In science, “may” is not a very strong word… This may be the reason that Mononuclear twins may or may not develop mononucliosis… Whether they kiss in the womb or not…
Scientists are always careful in these statements to err on the side of caution. I’d already seen some of the underlying scientific data a while back, and it’s compelling. I also have the inside scoop because my brother works in the field of DNA analysis. What it boils down to is that “sometimes” turns into a significantly large number when you’re talking about the replication of three billion base pairs.
Well, I have to admit that my brother has lots of DNA but knows nothing about this…
Oh jeez Troy, you can do better than that. It’s not about him being my brother, but about the difference between getting info from the Wikipedia versus from someone who actually works in a field. You should know that difference as well as anyone.
You haven’t said a thing about my cool java applet. Are you trying to hurt my feelings?
Here’s probably a stupid question, but maybe one you or your brother can answer… How do we know that DNA is helical? I can’t seem to find any source images that aren’t renderings… Maybe I didn’t look far enough, but, couldn’t find anything. I don’t believe the molecules are large enough to be directly observed, so, just curious…
Also, if the monozygotic twin starts with the same DNA, and this DNA is sometimes “mixed up” when cells split… wouldn’t that also be true of the amoeba? Or, is it’s genome too simple to get confused?
Just saw your comment about my brother… It was just a joke. I was basically restating the fact that you have access to information that I really know nothing about.
You stated that your brother works in the field of DNA and I was joking that my brother works in the fields and has lots of DNA. Nothing more than random silliness… Sorry to break my promise so soon to stop commenting… 🙁
Amoeba Applet, BTW, is very cute. Is it a girl? Perhaps you could teach it to multiply through division…
Glad you liked the applet!
Ah yes, making silly jokes on the internet – it’s so hard to get the tone right. Happens to me all the time. 🙂
I phoned my brother, after doing a little research on my own, and he set me straight. Amoebae are actually all different, and that’s why they survive so well. Mitosis does produce errors, and an amoeba can have over 200 times as many base pairs as a human. For example, one amoeba species is known to have around 670 billion base pairs in its DNA, as opposed to our paltry three billion.
Only a very small number of those base pairs express proteins, but the fact that the genus has been around on such a vast time scale means that it has a huge store of accumulated alternative genes to work with. It’s basically a genetic survival machine, far more robust and adaptable than we are (we’ve only been around as a species for a blip in time compared with the amoeba).
Errors in replication during mitosis, combined with the sheer massive parallel scale of amoeba replication, result in a variety of individuals in each new generation that are collectively prepared for an enormous range of possible environmental conditions.
So I stand corrected – it’s not one individual, it’s an army. One that has evolved in away that will likely let it be around long after our species is gone from the planet.
Did you ask him how they know the shape is helical?
As it happens, amoeba are able to have sex. So, there is the potential for lost of genetic diversity int he group.