About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.
Yes,it makes perfect sense. Here, another question arises.
Does absence of endomembrane system have to mean that it can't be multicellular??
Since prokaryotes have lot of unevenings in their plasma membrane(invaginations and outgrowths)and because of their small size, they have a high surface area which completely outnumbers the need for endomemebrane system as the absorption and transport of food molecules and others can take place much easily than in that of the eukaryotic plasma membrane. well, what do all of u have to say??
I would tentatively suggest the answer to this question is probably no because the history of all life on Earth is almost entirely about the history of prokaryotic life, and in all the billions of years prokaryotes ruled the Earth to the exclusion of all other forms of life they had ample opportunity to develop into multicellular versions of themselves. There should be something in the fossil record to show that multicellular organisms composed of different tissues and organs existed during the eons time when there were only prokaryotes around - nothing found so far that I'm aware of. But, and it's a pretty big but, I'm only just beginning my studies into biology, so this is just my hunch.
I don't know of any hard and fast rule as to why prokaryotes can't be multicellular by definition. I think some of the examples in this thread could quite convincingly be argued as basic multicellular organisms.
I think there is an important distinction between prokaryotes and eukaryotes that would prevent prokaryotes from forming complex multicellular organisms with differentiated tissues. That is energy. Since they lack mitochondria, they must undertake cellular respiration themselves, whereas a eukaryote may have hundreds or thousands of mitochondria per cell, each able to generate ATP. This means the genome can be much larger. If each specialised and nucleated animal cell has the full genome, that is a lot of energy expenditure on genes that will never be expressed. The fact that Prokaryotes are limited in their energy production by not being able to offload cellular respiration to someone else means that their genomes will always be limited in size and so will their complexity and ability to specialise.
More info here http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3152533/
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