Question about chloroplasts / mitochondria

[MNova]

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Hi,

Are chloroplasts and mitochondria self-replicating? Do they replicate during the S phase of interphase along with the other organelles but do it by themselves?

Also, per the endosymbiont hypothesis, I know chloroplasts are supposed to have originated from prokaryotic autotrophs. What about mitochondria? I believe Kaplan mentioned that they originated from prokaryotic heterotrophs, but was hoping someone could confirm / deny that.

Thanks!

 

[ethanyoo726]

They are self-replicating. They replicate on their own accord. You don't have to know when they do it, but it would make sense they would replicate with the rest of the cell considering that they are somewhat dependent on it.

Hmm...I think the mitochondria did come from a prokaryotic heterotroph. I could be wrong.

 

[joonkimdds]

I read somewhere that G1 phase makes mitochondria.

and yes they were anaerobic heterotrophs.

 

[MNova]

Awesome, thanks guys!

 

[Kneecoal]

i'll try and explain because i just read this a day or 2 ago. others will have to verify/back me up.

think of them like mini bacteria living inside the cell. essentially that's what they were before they became swallowed up by mama cell. i think what happens is that when mama cell splits up into 2 baby cells, mitochon./chloroplasts get distributed between the two, and then those will do their own splitting up when they're good and ready.

and it makes sense to distinguish chloroplasts as prokaryotic autotrophs form mitochon. as prokaryotic heterotrophs. if they weren't heterotrophs, they'd be autotrophs, which they're not. not a very good argument, but hey.