Why do Mitochondria and chloroplasts contain DNA? What evidence is there that these organelles have a seperate origin from thier host eukaryotic cell?
2006-11-15 17:15:01 · 4 answers · asked by Solari 1 in Science & Mathematics ➔ Biology
Because at one point they were free living organisms. They were taken in to a cell by endosymbiotic process.
The fast that they both have DNA different from the DNA of the cell, that they replicate free from the cell and that they have 2 layers of membrane, all point out that mitochondria and chloroplast were both free living cells.
2006-11-15 17:22:52 · answer #1 · answered by smarties 6 · 1⤊ 0⤋
There are many clues pointing towards the theory that mitochondria and chloroplasts were originally incorporated into a symbiotic relationship. The DNA is the biggest clue (due to size and sequencing results, and the fact that they have it at all), but a couple other points stand out; for instance, the membrane around the mitochondria and chloroplasts are more than a single layer, which would make sense in the case of endocytosis (anything taken in by endocytosis has an extra membrane layer added to it). Other points, such as reproduction (fission) and ribosomal structure also points to this.
Good luck!
2006-11-15 17:25:04 · answer #2 · answered by youngho1999 1 · 0⤊ 0⤋
I'm not sure about the evidence, but it is believed that mitochondria and chloroplasts were once bacteria that formed a symbiosis with the eukaryotic cell.
2006-11-15 20:31:53 · answer #3 · answered by Kevin R 1 · 0⤊ 0⤋
http://en.wikipedia.org/wiki/Endosymbiotic_theory
2006-11-15 17:23:52 · answer #4 · answered by Anonymous · 0⤊ 0⤋