"what are the current models for the orgins of prokaryotic and eukaryotic cells

Question

ap biology

Answer 1

do you mean organs or origins?

Answer 2

The endosymbiont theory would suggest that an early prokaryotic cell actually surrounded/engulfed another prokaryotic, but did not digest that cell.  Instead, that cell continued to live inside of it symbiotically much like algae living inside coral polyps.  The big cell may have been capable of eating heterotrophically, and the cell inside of it would have been able to produce nutrients photosynthetically.  Both would have benefitted the other.  You can imagine a number of arrangements where a cell living inside of a cell would be a mutually helpful living arrangement.

Anyway, after many many many generations, this endosymbiotic relationship would have evolved into one of absolute necessity where you end up with a eukaryotic cell with complex organelles like chloroplasts and mitochondria.  As evidence for this, both chloroplasts and mitochondria have their own little set of DNA (that resembles prokaryotic DNA) and a double-layered membrane, much like as if they had their own single membrane and were then engulfed within a larger cell.