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Okay, so, you’re offended because I referred to your cite as a “puff piece”? Okaaayyyyy… I hereby withdraw the accusation.
[ahem]
“Let it be known to all and sundry that John Mason, Food and Rural Affairs Correspondent for the Financial Times, is a worthy journalist, and one to be taken seriously.”
Okay?
“Last reviewed back in antiquity”? I don’t think so. And I know when they were written.
Now, Parameter, are you saying that these cites are incorrect? Are their facts wrong concerning the size of the various plant genomes? I challenge you to show me how they are wrong.
The article about rice genomics in the New York Times mentioned that plants may need large genes precisely because they can’t move around. Since they can’t flee predators or changing environmental conditions, they’ve evolved about a bajillion sophisticated chemical tricks.
I thought plants didn’t have mitochondria–don’t they have chloroplasts and get their energy from photosynthesis?
I admit that I really don’t even know what “genome” means. I believe(d) that it meant the wad of genes as they were assembled into chromosones.
I still curious as to why plants’ mitochondria have such large genomes–so many more genes than do we animals. I understand the plant-chemical-warfare argument but why would the the mitochondria require such a big genome.
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D. D. Goose: I didn’t really mean to insult your references so badly but, as I read the footnotes, the dates that you mention were the dates the web-page was last reviewed and not the date they were written. The publication of the article referenced was in the journal Science, which would seem to be a highly reputable source.
It’s simply the entire genetic content of a living thing. This includes but is certainly not limited to actual genes. So two living things can have the same size genome with a different number of genes. Just like two books of identical physical sizes can differ in the total number of words.
According to my Cell Biology text book, there are a great number of creatures great and small with genomes that exceed the human: hany plants including beans, just about all cartilaginous fish including sharks, as well as many amphibians including frogs and newts. The lily’s genome length is about 100 times that of the human (about 100 billion or so base pairs). So as others have said, genome length really isn’t related to complexity. To continue my role as an analogy whore: Einstein’s Nobel Prize winning paper on the photoelectric effect is smaller than the hardcover edition of Hop on Pop .
I think you’re sorta falling into the same trap you did with the OP. A larger mitochondrial genome doesn’t necessarily mean the a plant mitochondrion will produce more ATP than an animal mitochondrion. It could be that plant mitochrondria simply require more proteins to extract energy through a non-photosynthetic pathway. This could in fact result in much less ATP than animal mitochondria produce, but since its essentially a back-up generator, it would not a big deal.
The date the research was written up does not signify.
The date the research was posted on the web page does not signify.
The length of time elapsed since the web page was last updated does not signify.
All that signifies is whether the information contained on the web page is correct.
So, is the information contained in those web pages incorrect?
No, I would venture to say that it is not. And if you think that the information is incorrect, then according to the SDMB ground rules, it is incumbent upon you to go and find cites that refute the facts given in my “old” cites.
Here is a website from 1996. Just because it’s six years old, would you automatically assume that its information is incorrect?
Here at the SDMB, if you’ve got a genuine beef with the accuracy of someone’s cites, then you are entitled to speak up. But if it’s merely that you think their cites are “old”, then keep it to yourself.
Plants have both mitochondria (which are functionally essentially identical to animal mitochondria, despite the fact that the plant mitochondrial DNA genome may be larger - the extra DNA appears to be “junk”, the actual proteins used by the plant mitochondrion are similar to the animal ones), and chloroplasts. Chloroplasts are where photosynthesis is performed. Mitochondria are used for aerobic respiration (the infamous electron transport chain you see illustrated in any basic biochemistry textbook). Plants respire just as animals do, and they require oxygen to “breathe” - it’s just that photosynthesis produces more oxygen as a byproduct than the plant’s aerobic metabolism consumes, so plants are net producers of oxygen rather than net consumers like animals.
Thanks, Alphagene and Artemis. I had gotten a little of that from the FSU site that I linked, but you have given a much more detailed and usable dose.
Should I them assume that the answer to “What does it mean?” in the OP is: “not much”? Or am I being overly simplistic with that dismissal?
I admit that I have always been fascinated by the mitochondria; much more so than by the bacteria. Perhaps that’s because they are the only organelles to have their own DNA. --Uhhh, I think that I just read somewhere that this is also true about the chloroplasts–are they and the mitochondria both members of a larger class?
I have a couple of Biochemistry texts at home, Artemis, but having never completed a Biology course has left me in sort of deep water trying to read them.
Thanks for your help again. Do we quit discussing rice or is there yet more to be gleaned?
Yeah, parameter, I’d say that that’s a fair assessment. There’s no simple relationship between an organism’s complexity and it’s genome size (although to be fair, I’d consider angeosperm plants to be complex organisms).
Yes, they are evolutionarily related. In fact, current thinking is that eukaryotic cells (cells with a true nucleus, the type of cell found in plants and animals) are the result of a type of bacterial symbiosis - chloroplasts and mitochondria are genetically related to Archaebacteria, and it’s thought that in the dim and distant past their ancester entered another type of bacterial cell (either in an attempt to parasitize it, or more likely the other cell tried to consume the Archaebacteria and didn’t completely succeed), and over time, a co-operative relationship developed between the two, with each relying more and more on the other. Now neither can survive on its own - the mitochondria and chloroplasts have to import the messenger RNA for some of their necessary proteins from the nucleus of the eukaryotic cell, and of course the eukaryotic cell needs its mitochondria (and, if a plant) chloroplasts to perform essential biochemical reactions. It’s a complete symbiosis, and kind of eerie when you stop to think about it - our cells have cells of their own inside them!
What does it mean?..to quote Mr Natural, ‘it don’t mean shit.’
As SNenc wisely put it, it’s all about proteins, or to be thoroughly up-to-date, proteomics, which is the quantitative analysis of the entire complement of proteins in a living system. Genes are simply information on how to build proteins. An awful lot of the information (read base pairs) in any given gene is related to regulation of the gene (should I, or shouldn’t I make this protein), or contains instructions on how the nascent protein is to be processed and/or transported. Only about 2% of the genome ends up as an mature, expressed protein.
Genomics is dead. Long live Proteomics!!!
Before I can swallow that “Genomics is dead. Long live Proteonics” you have **got to **talk about the missing 98% of the genome. I’m assume that by “expressed” you have included such things as processing and/or transporting the constructed proteins in the 2%.
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Many, many thanks, artemis. And what Eggles said–for your posts.
