myers@tybalt.caltech.edu.UUCP (05/06/87)
There's been a certain degree of talk about kingdoms of life: how life
is generally classified. I think the most commonly accepted version is
now:
Type General Characteristics
-------- -----------------------
Animals Multicellular, no cell walls, no photosynthesis, usually mobile
You know what an aminal is.
Plants Multicellular, cell walls, photosynthesis, generally sessile
You know what a plant is.
Fungi Multicellular, cell walls, no photosynthesis, generally sessile
Fungi of all sorts -- mushrooms, etc.
Protists One-celled life with a cell nucleus
Protozoa, yeasts, most one-celled algae
Monerans One-celled life, no cell nucleus
Bacteria, cyanobacteria ('blue-green algae')
-------------------------------------------------------------------------------
Bob Myers myers@tybalt.caltech.edu
...seismo!tybalt.caltech.edu!myersjerryn@tekig4.UUCP (05/07/87)
In article <2597@cit-vax.Caltech.Edu> myers@tybalt.caltech.edu.UUCP (Bob Myers) writes: >There's been a certain degree of talk about kingdoms of life: > You know what an aminal is. Yes, an aminal is a jeast what balks in the wungle. Anyone who doesn't know that is an asbolute ingoramus! :-)
pan@well.UUCP (Philip Nicholls) (05/10/87)
And then, there are those pesky slime molds. What is the latest with them, anyway?
simon@its63b.ed.ac.uk (ECSC68 S Brown CS) (05/10/87)
In article <2597@cit-vax.Caltech.Edu> myers@tybalt.caltech.edu.UUCP (Bob Myers) writes: >There's been a certain degree of talk about kingdoms of life: how life >is generally classified. I think the most commonly accepted version is >now: > > Type General Characteristics > -------- ----------------------- > > Animals Multicellular, no cell walls, no photosynthesis, usually mobile > > Plants Multicellular, cell walls, photosynthesis, generally sessile > > Fungi Multicellular, cell walls, no photosynthesis, generally sessile > > Protists One-celled life with a cell nucleus > Protozoa, yeasts, most one-celled algae > > Monerans One-celled life, no cell nucleus > Bacteria, cyanobacteria ('blue-green algae') > > >Bob Myers myers@tybalt.caltech.edu > ...seismo!tybalt.caltech.edu!myers I'd thought* that these "kingdom" classifications were a sub-category of the eukaryotes, and that the prokaryotes (bacteria and stuff) were completely separate - ie: Life ----- | | -------------------------------------- | | Eukaryotes Prokaryotes ----------- ----------- | | | | | | | | | | | | a p f ..... [various bacteriological "kingdoms"] n l u i a n (anyone know what there are?) m n g a t i l s s I can't remember what the fundamental differance between the eukaryotes and the prokaryotes is, or even if there really is one at all! I do remember that all the prokaryotes are haploid, so it would be very nice and convenient if the eukaryotes were all diploid, wouldn't it? Anyone know anything about any of this? ------------------------------------------------------------------------ *Disclaimer: I'm a mathematician, not a biologist, so I probably don't completely know what I'm talking about here. ------------------------------------------------------------------------ -- ---------------------------------- | Simon Brown | UUCP: seismo!mcvax!ukc!{its63b,cstvax}!simon | Department of Computer Science | JANET: simon@uk.ac.ed.{its63b,cstvax} | University of Edinburgh, | ARPA: simon%{its63b,cstvax}.ed.ac.uk ... | Scotland, UK. | @cs.ucl.ac.uk ---------------------------------- "Life's like that, you know"
gallagher@husc4.UUCP (05/15/87)
In article <396@its63b.ed.ac.uk> simon@its63b.ed.ac.uk (ECSC68 S Brown CS) writes: > >I can't remember what the fundamental differance between the eukaryotes >and the prokaryotes is, or even if there really is one at all! I do remember >that all the prokaryotes are haploid, so it would be very nice and convenient >if the eukaryotes were all diploid, wouldn't it? Anyone know anything about >any of this? > >---------------------------------- >| Simon Brown | UUCP: seismo!mcvax!ukc!{its63b,cstvax}!simon Prokayotes and eukaryotes are very different. The most obvious difference is that eukaryotes possess a discrete nucleus (eu-caryon = true nucleus), while prokaryotes do not. Also, prokaryotes have only 1 chromosome, without histones, while eukaryotes have more than 1 chromosome, with histones. Prokaryotes do not have a nucleolus, endoplasmic reticulum, golgi apparatus, mitochondria, lysosomes, or microtubules, while all eukaryotes do. Prokaryotes have ribosomes that are 70 S long, while eukaryotes have 80 S ribosomes (except in their mitochondria and chloroplasts). Prokaryotes exchange genetic information with plasmids, while eukaryotes do it by gamete fusion. Electron transport takes place in the cell membrane of prokaryotes, while it takes place in the organelle membranes of eukaryotes. There are many other differences. The difference between prokaryotes and eukaryotes is probably the most basic difference among living things. Prokaryotes are often divided into two kingdoms: Eubacteria and Archebacteria. Some people may recognize other kingdoms as well. Unfortunately, I'm not too familiar with bacteria, but a good place to look would be in books by Lynn Margulis, a BU professor who studies them. I think it is believed that the Progenotes - the ancestral cells - gave rise to the Archebacteria, Eubacteria, and the Urkaryotes (a completely extinct kingdom). Apparently, eubacteria started living inside urkaryotes and this was the first eukaryote (or protist). This is known as the "endosymbiotic hypothesis." The mitochondria and perhaps the nucleus of the eukaryotic cell are thus the descendants of eubacteria, and the cytoplasm of the cell is the descendant of urkaryotes. Later, another eubacterium containg chlorophyll started living inside the cell, and this became the chloroplast of photosynthetic protists and plants. Paul Gallagher
lucius@mit-prep.ARPA (Lucius Chiaraviglio) (05/19/87)
>In article <396@its63b.ed.ac.uk> simon@its63b.ed.ac.uk (ECSC68 S Brown CS) >writes: >>I can't remember what the fundamental differance between the eukaryotes >>and the prokaryotes is, or even if there really is one at all! I do remember >>that all the prokaryotes are haploid, so it would be very nice and convenient >>if the eukaryotes were all diploid, wouldn't it? Anyone know anything about >>any of this? Paul Gallagher said most of what needed to be said about the differences between prokaryotes and eukaryotes, but I should also add that eukaryotes can have any sorts of ploidys. Organisms are known which are monoploid (haploid) all the way up to at least octaploid, with gradations into situations where the various genomes are different enough that they can no longer be called copies of each other, although the organism is still called polyploid because the genomes are similar, all the way to the point where all the genomes are very different and cannot do with each other, at which point they have merged. Also, some organisms are known that do not have integer numbers of copies of their genomes -- these include things as diverse as ciliated protozoa which have macronuclei in which the genes are present in huge numbers of copies but the spacers between genes have been mostly degraded, and some insects such as scale insects in which all cells except the germ cells lose certain chromosomes. In article <1991@husc6.UUCP> gallagher@husc4.UUCP (paul gallagher) writes: > . . .eukaryotes have more than 1 chromosome, with histones. Except for some such as dinoflagellates, which seem to have no histones, although they do have some proteins associated with their DNA. > Prokaryotes do >not have a nucleolus, endoplasmic reticulum, golgi apparatus, mitochondria, >lysosomes, or microtubules, while all eukaryotes do. Prokaryotes have ribosomes >that are 70 S long, while eukaryotes have 80 S ribosomes (except in their >mitochondria and chloroplasts). But see note about urkaryotes below. . . Also, 'S' is not a unit of length. It is a measure of sedimentation velocity, which is dependant on weight, density, and shape. I don't rremember its exact composition (it has a 10**13 and a seconds somewhere in there, but I don't remember whether they are in the numerator or the denominator), but units of length and molecular weight are definitely absent from it. (I should really remember exactly what it is -- I'll go look it up, but not now.) >I think it is believed that the Progenotes - the ancestral cells - gave rise >to the Archebacteria, Eubacteria, and the Urkaryotes (a completely extinct >kingdom). Apparently, eubacteria started living inside urkaryotes and this >was the first eukaryote (or protist). . . . According to a commentary in a recent issue (2 - 3 weeks ago) of either Science or Nature (I think the latter), some urkaryotes (though the article did not name them that, calling them primitive eukaryotes instead) may still be around, and Giardia may be among these. They had examined a different parasitic organism, and found that although it had a nucleus and either Golgi apparatus or endoplasmic reticulum (I forget which) as is characteristic of eukaryotes, it lacked mitochondria and microsomes, and had 70S ribosomes which were approximately equally unrelated to both prokaryotic and eukaryotic ribosomes (according to inspection of their nucleotide sequences, that is). While they did not examine the ribosomes of Giardia and its free-living relatives, they have the other characteristics of these above-mentioned parasites, and some of the free-living ones manage to use oxygen without either mitochondria or peroxisomes (details not given). Also, some of these candidate urkaryotes have sizes characteristic of prokaryotes. -- -- Lucius Chiaraviglio seismo!tardis!lucius lucius@tardis.harvard.edu