Question

How did animal cells acquire mitochondria​

Answer 1

Mitochondria originated by a endosymbiotic event when a bacterium was captured by a eukaryotic cell. Two changes must have occurred as the bacterium became integrated into the recipient cell and evolved into the mitochondrion (or chloroplast).

Answer 2

Mitochondria originated by a endosymbiotic event when a bacterium was captured by a eukaryotic cell. ... Two changes must have occurred as the bacterium became integrated into the recipient cell and evolved into the mitochondrion (or chloroplast).