Question

"Human cells contain DNA sequences, that match the sequences found in bacterial $16$S rRNA." Which of the following is correct regarding this statement?

• A. The statement is untrue because healthy human cells should contain no bacteria DNA.
• B. The statement is true because mitochondria contain bacterial DNA sequences.
• C. The statement is untrue because there is no such thing as rDNa, only rRNA.
• D. The statement is true because the $16$S sequences are part of the human $18$S sequences.
• E. The statement is true because there are many human sequences that match $16$S sequences.

Answer 1

Answer: (B)

The statement is true because mitochondria contain bacterial DNA sequences.

Bacteria have 70S ribosome. The 30S subunit has 16S rRNA and 50S subunit, has 23S and 5S rRNA. According to endosymbiotic theory, compartmentalization of prokaryotic cells by infolding of plasmalemma resulted in the formation of intracellular membrane-bound organelles. Endosymbiosis of the colorless cyanobacterium, into another bacterium, gave rise to mitochondria and therefore the genome of these semiautonomous eukaryotic organelles share sequences with that of bacterial DNA. So, the correct answer is option B.