Question about a cell

Question

How can you look at a diagram (of plasmodium falciparum’s simplified cell structures) and prove that apicoplasts once evolved from free-living, prokaryotic organisms?

the diagram showed the nucleus, golgi, ER, mitochondria, apicoplast with DNA

Answer 1

I'm guessing that in class, you looked at the deductions that support the idea that mitochondria and chloroplasts are captured cells rather than 'inventions' of eukaryotic cells. Briefly, we observe that most organelles DON'T have their own genetic material (DNA), since they arose from structures within the cell and thus there would be no pathway and no need for them to have their own genetic instructions. Having DNA in an organelle creates all sorts of challenges for the cell, so it's difficult to imagine how such an arrangement came about.

Nonetheless, mitochondria and chloroplasts have their own DNA... and most tellingly, everything about that DNA looks more like BACTERIAL DNA than eukaryotic DNA--its circular, the machines that are coded for resemble bacterial ones, the way the coding is done resembles bacteria more than the host cell.

Note that in your list, you report that the depicted apicoplast has DNA; check the STRUCTURE of the DNA as well (if shown). Bacterial DNA is circular; eukaryotes have linear DNA.

Another thing to check for is the membrane surrounding it. For mitochondria and chloroplasts, there are at least TWO layers of membrane around the organelle. One is a remnant of the ORIGINAL membrane of the captured organism; the OTHER was contributed by the cell that captured it, because eukaryotic cells eat by engulfing (wrapping in membrane). Look up 'phagocytosis' images to learn more.