from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Having or consisting of one cell; one-celled: unicellular organisms.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Describing any microorganism that has a single cell
- n. A single-celled organism; a unicell.
from the GNU version of the Collaborative International Dictionary of English
- adj. Having, or consisting of, but a single cell.
from The Century Dictionary and Cyclopedia
- Consisting of a single cell, as some infusorians and some cryptogams; pertaining to or exhibiting only a single cell, as most of the protozoan animals and protophytic plants, and the undeveloped ova of all metazoan animals.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. having or consisting of a single cell
Sorry, no etymologies found.
So Mike has been cataloging a number of components that have one use in unicellular life, and a different use in multicellular life, to show that front loaded designs wouldn't necessarily be lost in the future.
Cytosine deamination, controlled variation and the immunological functions are nicely linked and analogous systems in unicellular organisms can be found.
For example purposeful behavior surely occurred in unicellular eukaryotic ancestors of modern organisms like paramecia and euglena who perform rather complex adaptive movements.
A prediction of front-loading is genes required for multicellularity being discovered in unicellular organisms, and I have previously suggested looking at amoebae, one of the oldest eukaryotes.
As one who believes that mutations in unicellular organisms are not random this proposal is particularly intriguing.
Have RAs or related molecules been discovered in unicellular organisms?
"Have RAs or related molecules been discovered in unicellular organisms?"
If we can't find RAs or related molecules (that they could have evolved from) in unicellular organisms, then it would seem to point to at least a second design event, wouldn't it?
It hasn't been demonstrated that RAs or their precursors existed in unicellular organisms.
Work during the past few years has show that cyclic AMP exerts several regulatory functions of vital importance in unicellular organisms, functions governing the adaptation of the cell to its surroundings.