Prokaryotes and Eukaryotes

All living organisms belong to one of two major groups, either eukaryotes or prokaryotes.

The eukaryotes possess chromosomes contained in a defined nucleus.

The prokaryotes, such as bacteria, have no nucleus or chromosomes.

That's the definition in Guide To the Oceans, by Dr. John Pernetta.

Let's see what Dictionary.com has to say:

Eukaryotes

any organism having as its fundamental structural unit a cell type that contains specialized organelles in the cytoplasm, a membrane-bound nucleus enclosing genetic material organized into chromosomes, and an elaborate system of division by mitosis or meiosis, characteristic of all life forms except bacteria, blue-green algae, and other primitive microorganisms.

Origin: < NL Eukaryota, earlier Eucaryotes (1925) "those having a true nucleus," equiv. to eu- eu- + Gk káry(on) nut, kernel

Prokaryotes

any cellular organism that has no nuclear membrane, no organelles in the cytoplasm except ribosomes, and has its genetic material in the form of single continuous strands forming coils or loops, characteristic of all organisms in the kingdom Monera, as the bacteria and blue-green algae.

And what is Monera, you're asking yourself?

a taxonomic kingdom of prokaryotic organisms that typically reproduce by asexual budding or fission and have a nutritional mode of absorption, photosynthesis, or chemosynthesis, comprising the bacteria, blue-green algae, and various primitive pathogens.

Origin: < NL (1869), pl. of monēron, coinage based on Gk monrēs solitary, single, deriv. of mónos alone, only

So we'll start out this blog by discussing marine bacteria and algae.