How are Mitochondria and Chloroplast similar to Prokaryotic bacterial cells?

The similarity of mitochondrion and chloroplast with prokaryotic cells is the most compelling evidence that supports  Endosymbiont theory which explains the evolution of eukaryotic animal and plant cells. Refer figure.

Similarity between Mitochondrion and Prokaryotes

In cell structure

• The bacterial plasma membrane resembles the inner mitochondrial membrane in many aspects. In mitochondrion, the inner membrane is folded to form cristae which is the site of oxidative phosphorylation and electron transport and associated ATP production.
• Bacterial plasma membrane has infoldings called mesosomes which is thought to be involved in respiration and DNA replication.

In Genetic material

• Mitochondrion is a semi autonomous organelle with its own DNA called as mt DNA.
• Like Bacterial DNA, mt DNA is circular, double stranded and not covered by a membrane.
• Both Bacterial DNA and mt DNA  are devoid of histone proteins
• Generally lack introns
• Protein synthesis initiated by formyl methionyl tRNA (f-met tRNA) and in both mitochondria and bacteria protein synthesis can be inhibited by the same inhibitor chloramphenicol
• Replication, transcription and translation similar to bacteria.
• Sequence alignment studied reveal high degree of relatedness between mt genes and bacterial genes

In both cells, ribosomes are small 70 S ribosomes

Mitochrondria and chloroplasts replicate by a splitting process similar to binary fission in prokaryotes

Similarity between Chloroplast and Prokaryotes

Chloroplast is similar to mitochondrion in many aspects.

In Genetic material

• Chloroplast is a semi autonomous organelle with its own DNA called as cp DNA.
• Like Bacterial DNA, cp DNA is circular, double stranded and not covered by a membrane.
• Both Bacterial DNA and cp DNA  are devoid of histone proteins
• Generally bacterial DNA, mt DNA and cp DNA  lack introns
• Small 70 S ribosomes.
• Protein synthesis initiated by formyl methionyl tRNA (f-met tRNA).
• Replication, transcription and translation similar to bacteria.
• Transcription and translation are similar in chloroplasts and eubacteria: most chloroplast genes are transcribed as polycistronic units, their mRNAs are not capped, no poly(A) tails are added, and they possess a Shine Dalgarno ribosome binding sequence.
• The RNA polymerase of liverworts contains α and β subunits and the amino acid sequence has great similarity to those of E.coli.
• DNA sequences analysis suggest high degree of sequence similarity between cyanobacteria  and cp DNA of higher plants. Most cp DNA is thought to be evolved slowly in sequence and structure from cyanobacterial DNA.