Hi, I have a question as title: Does transcription occurs in mitochondria and chloroplast? Because in mitochondria we have DNA in loops and in chloroplast we also have DNA. Thank you so much!!!
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Yes it does! As in all bacterial cells, the processes replication, transcription and translation all occur inside them:) Dont forget mitochondria and chloroplasts contain ribosomes as well!
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Hello, first of all thank for helping me, I have more question. So in mitochondria, chloroplast, after transcription occurs, where does translation occur?
As eukaryotes, I assume after transcription occurs mitochondria, mRNA will go out and come to ER to make translation, right?
And the same is for chloroplast.
Thank you so much!!!
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Good question!
First thing, we must keep in mind ribosomes (70S) are present in both, mitochondria and chloroplasts. When mRNA is transcribed, it always passes to the ribosomes for translation. Therefore, in these organelles translation occurs directly in their “cytoplasm” - which is “mitochondrial matrix” in mitochondria and “stroma” in chloroplasts.
In eukaryotes, when mRNA is normally transcribed from the nuclear DNA, it passes out of nucleus and attaches to ribosomes in the cytoplasm for translation. Only if in the beginning of the translation we produce a “signal recognition polypeptide” on the ribosome, the ribosome with mRNA travels a-mid translation to the rough ER, where it attaches to its membrane. Once attached, the translation finalises on rough ER and the polypetide chain goes into the lumen of the rough ER.
Hope that explains:)
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Oh i learned a lot from you, thank you so much!!! I really appreciate it! Have a great day!
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hey! I thought that 70s ribosomes were only found in prokaryotes while 80s ribosomes in eukaryotes. Would this mean the we have both 70s and 80s ribosomes and prokaryotes only 70s? Thanks in advance 
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Yes what you’re saying is correct, eukaryotes do have both 70s and 80s. In eukaryotes the 70s ribosomes are in the mitochondria and chloroplasts and in prokaryotes they are in the cytoplasm. Note that 80s ribosomes are unique to eukaryotes.
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ohhh okay! Thank you soo much 
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