ydoaPs Posted August 2, 2004 Share Posted August 2, 2004 Last year I had to take a bio class. Early in the book, it talks about Cell Theory. In second semester it talked about cells evolving from bubbles of lipids(it had a name for them, but i don't remember it). They aren't compatible. Which one is in the standard model for biology? Link to comment Share on other sites More sharing options...
admiral_ju00 Posted August 2, 2004 Share Posted August 2, 2004 The cell theory is. I've not heard of that other one. As for that 2nd one, are you sure you're not talking about a cell membrane as opposed to an actual theory? Link to comment Share on other sites More sharing options...
DimShadow7 Posted August 2, 2004 Share Posted August 2, 2004 I think the other thing with the cells bubbling out of puddles of lipids is called chemical evolution. I have a vague memmory of this but I remember that both were compatible to some extent. Could you expand on why they are not compatabile? Thanks, DimShadow7 Link to comment Share on other sites More sharing options...
ydoaPs Posted August 2, 2004 Author Share Posted August 2, 2004 part of cell theory is "cells only come from other cells". i was not confusing it with cell membrane. i was talking about these bubbles of lipids that my bio book said cells evolved from. Link to comment Share on other sites More sharing options...
Sayonara Posted August 2, 2004 Share Posted August 2, 2004 When you say "evolved", do you mean the historical structure of cells as a group, or the development of a single cell? Link to comment Share on other sites More sharing options...
ydoaPs Posted August 2, 2004 Author Share Posted August 2, 2004 the first cell Link to comment Share on other sites More sharing options...
LucidDreamer Posted August 2, 2004 Share Posted August 2, 2004 "Micelles form from amphipathc lipids that position the hydrophobic tails in the center of the lipid aggregations with the polar head groups facing outward" Micelles form spontaneously when amphipathic lipids are placed in water. It has been suggested that the first cell was just a piece of DNA or RNA, capable of reproducing, contained within a micelle. Because they lack fossil records they really have no idea what life was life before the earliest found prokaryotes. Link to comment Share on other sites More sharing options...
admiral_ju00 Posted August 2, 2004 Share Posted August 2, 2004 It has been suggested that the first cell was just a piece of DNA or RNA, capable of reproducing, contained within a micelle. I don't think it could have been the DNA. RNA, is a better candidate. Link to comment Share on other sites More sharing options...
Skye Posted August 2, 2004 Share Posted August 2, 2004 Even RNA is a bit tricky as a starting point, as polymers of RNA don't form very easily. So it may have been something similar, but not quite the same. Anyway, cells are bubbles of lipids (with lots of other stuff) so it's not really contradictory to say that cells formed from bubbles of lipids. Whether they actually did or not is very difficult to say though. Link to comment Share on other sites More sharing options...
ydoaPs Posted August 2, 2004 Author Share Posted August 2, 2004 cell theory makes it contradictory. i don't think a piece of random RNA in a lipid bubble counts as life. there was no metabolism or reproduction capabilities Link to comment Share on other sites More sharing options...
Sayonara Posted August 2, 2004 Share Posted August 2, 2004 We call things like erythrocytes "cells". Link to comment Share on other sites More sharing options...
ydoaPs Posted August 2, 2004 Author Share Posted August 2, 2004 what is wrong with calling red blood cells cells? Link to comment Share on other sites More sharing options...
Sayonara Posted August 2, 2004 Share Posted August 2, 2004 They have no metabolism or reproduction capabilities, which are the criteria by which you claimed "a piece of random RNA in a lipid bubble" is not a cell. Link to comment Share on other sites More sharing options...
ydoaPs Posted August 2, 2004 Author Share Posted August 2, 2004 "a piece of RNA in a lipid bubble" is not produced by a cell; red blood cells are. I should have phrased post #10 better. when i said it wasn't a cell, i meant it wasn't life. Link to comment Share on other sites More sharing options...
ydoaPs Posted August 2, 2004 Author Share Posted August 2, 2004 my point is "a piece of DNA in a lipid bubble" is not produced by cells, so it shouldn't be considered a cell. Link to comment Share on other sites More sharing options...
LucidDreamer Posted August 2, 2004 Share Posted August 2, 2004 "Cells are the basic units of life. They are the building blocks of all organisms, from bacteria to animals. Cells are thought to be the units for life. This is stated in the cell theory. The cell theory is as follows: 1. All living things are composed of one or more cells. 2. Cells are organisms' basic units of structure and function. 3. Cells come only from existing cells." Cell theory only applies to life today. Saying that early life and proto-cells don't adhere to the principles of cell theory is like saying early mammal ancestors don't meet the qualifications of mammals--such as warm-blood, mammary glands, fur, etc. Of course mammal ancestors don't meet the qualifications. Before there were mammals there were no mammals. Before there were modern cells that meet the qualifications of cell theory there were proto cells that acquired the modern characteristics as they evolved. Link to comment Share on other sites More sharing options...
ydoaPs Posted August 3, 2004 Author Share Posted August 3, 2004 early mammal ancestors weren't mammals they were early mammal ancestors. photosynthetic protists were the ancestors of plants, but they aren't plants. Link to comment Share on other sites More sharing options...
admiral_ju00 Posted August 3, 2004 Share Posted August 3, 2004 early mammal ancestors weren't mammals they were early mammal ancestors. photosynthetic protists were the ancestors of plants, but they aren't plants. And your point being....?!? Link to comment Share on other sites More sharing options...
ydoaPs Posted August 3, 2004 Author Share Posted August 3, 2004 "Saying that early life and proto-cells don't adhere to the principles of cell theory is like saying early mammal ancestors don't meet the qualifications of mammals--such as warm-blood' date=' mammary glands, fur, etc. Of course mammal ancestors don't meet the qualifications. Before there were mammals there were no mammals. [/quote'] he said that protocells didn't obey cell theory, because early mammal ancestors didn't have all the qualities of mammals. i said early mammal ancestors weren't mammals, so that argument is useless. Link to comment Share on other sites More sharing options...
LucidDreamer Posted August 3, 2004 Share Posted August 3, 2004 he said that protocells didn't obey cell theory, because early mammal ancestors didn't have all the qualities of mammals. i said early mammal ancestors weren't mammals, so that argument is useless. hmm, that’s not what I was trying to say. I was trying to say that there is no use in applying cell theory to early proto-cells because that theory was intended for modern cells. However, I suggested that early cells could have been pieces of RNA (that’s for admiral ju) capable of reproducing within micelles. This organism would qualify for all of the cell theory principles. Except of course for the first cell ever which would not qualify under the 3rd requirement. Link to comment Share on other sites More sharing options...
ydoaPs Posted August 3, 2004 Author Share Posted August 3, 2004 a piece of RNA in a lipid bubble cannot reproduce. it would need other chemicals to replicate the RNA. how would it devide. Link to comment Share on other sites More sharing options...
LucidDreamer Posted August 3, 2004 Share Posted August 3, 2004 Modified RNA and RNA derivatives can perform certain chemical functions but beyond that I have no idea how early cells replicated. If I did I would have already picked up my Nobel Prize. Link to comment Share on other sites More sharing options...
Skye Posted August 3, 2004 Share Posted August 3, 2004 Well using the mammal analogy, I can postulate that all mammals come from pre-existing mammals. All observations of mammal reproduction support this position. But of course, at some point a mammal was born from something that wasn't a mammal. That was the start of mammaldom. Link to comment Share on other sites More sharing options...
Arg Posted August 4, 2004 Share Posted August 4, 2004 Of course you're running into problems reconciling everything: it's all a classification issue. There aren't any mammals, or reptiles, or bacteria, just stuff on a spectrum grouped for convenience. You can say that a mammal is a being with all these various characterstics, and you can convincingly lie to yourself about that most of the time, but if you go backwards in their evolution you'd run across creatures so close to mammals it'd be hard to tell the difference. At that point, all that separates this from that is a wish and a whim. Too many so-called scientists forget that. Link to comment Share on other sites More sharing options...
Sayonara Posted August 4, 2004 Share Posted August 4, 2004 Whooooooooooooooooooooosh. Watch out for low-flying points. Link to comment Share on other sites More sharing options...
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