Question

Which of the following describes the mitochondria?

A. They typically have larger genomes than chloroplasts.
B. Extensive editing occurs on their RNAs.
C. They utilize dynamin-like GTPases to divide from the outside.
D. The organization of gene clusters in their genome is strikingly similar to cyanobacteria.
E. All of these describe mitochondria.

Answer 1

Mitochondria share a close relationship with alpha-proteobacteria and have similar division processes to prokaryotes, supporting the endosymbiotic theory. They have their own genomes but cannot survive outside a host cell, and their RNAs undergo extensive editing, making option B the correct answer.

Step-by-step explanation:

The mitochondria are complex organelles known as the powerhouses of the cell because of their role in energy production. Their characteristics suggest a relationship with alpha-proteobacteria, supportive of the endosymbiotic theory. This theory posits that mitochondria originated as free-living bacteria that were engulfed by ancestral eukaryotic cells. Mitochondria have their own genomes, which are circular DNA molecules attached to the inner mitochondrial membrane, and their gene organization bears a resemblance to alpha-proteobacteria.

Mitochondrial division is reminiscent of binary fission seen in prokaryotes, employing dynamin-like GTPases. The mitochondrial genome is highly conserved across eukaryotic species; however, it shows a rapid mutation rate. Interestingly, mitochondrial DNA is maternally inherited, making it a useful tool for tracing genealogical relationships. Lastly, despite their independent genome, mitochondria cannot survive without a host, as many essential genes have been transferred to the nuclear genome over evolutionary time. Examining the options given in the question, it is evident that description B. Extensive editing occurs on their RNAs is accurate, implying that the best answer to the question "Which of the following describes the mitochondria?" would be option B.