Final answer:
Mitochondria, responsible for cellular energy production, are found in both plant and animal cells as part of their common eukaryotic cell structure.
Step-by-step explanation:
Mitochondria are membrane-enclosed organelles that are found in eukaryotic cells and hence are present in both plant and animal cells. These organelles, often called the "powerhouses" or "energy factories" of the cell, are responsible for producing adenosine triphosphate (ATP), which is the primary energy carrier in cells. Mitochondria perform cellular respiration tasks, including the Krebs cycle and electron transport, which convert nutrients into ATP, a process critical for sustaining cell activities such as movement and division.
In terms of cell energy needs, cells that demand a high level of energy like muscle cells and sperm cells contain numerous mitochondria to meet their energy requirements. Plant cells, while also possessing mitochondria, have additional components such as chloroplasts for photosynthesis, which are not found in animal cells. Conversely, animal cells have structures such as centrosomes and lysosomes not typically found in plant cells. However, when considering mitochondria specifically, they are a common feature in the cells of both organisms.