Why do both plant and animal cells need mitochondria?

Both plant and animal cells need mitochondria because they are essential for energy production through cellular respiration. Mitochondria convert nutrients into adenosine triphosphate (ATP), the energy currency of the cell, which is vital for various cellular processes. While plant cells also have chloroplasts for photosynthesis, mitochondria play a crucial role in breaking down organic molecules to release energy, making them indispensable for both types of cells.