Both the chloroplast and the mitochondrion are organelles found in the cells of plants, but only mitochondria are found in animal cells. The function of chloroplasts and mitochondria is to generate energy for the cells in which they live. The structure of both organelle types includes an inner and an outer membrane. The differences in structure for these organelles are found in their machinery for energy conversion.
The shape of mitochondria is different than that of chloroplasts. Chloroplasts have an ellipsoidal shape, which is symmetrical across three axes. Mitochondria, on the other hand, are generally oblong, but tend to change shape rapidly over time.
Mitochondria Inner Membrane
The inner membrane of a mitochondrion is elaborate in comparison with the chloroplast. It is covered in cristae created by multiple folds of the membrane to maximize surface area. The mitochondrion uses the vast surface of the inner membrane to perform many chemical reactions. The chemical reactions include filtering out certain molecules and attaching other molecules to transport proteins. The transport proteins will carry select molecule types into the matrix, where oxygen combines with food molecules to create energy.
Chlorplast Inner Structure
The inner structure of chloroplasts is more complex than that of mitochondria. Within the inner membrane, the chloroplast organelle is composed of stacks of thylakoid sacks. The stacks of sacks are connected to each other by stromal lamellae. The stromal lamellae keep the thylakoid stacks at set distances from each other. Chlorophyll covers each stack. The chlorophyll converts sunlight photons, water and carbon dioxide into sugar and oxygen. This chemical process is called photosynthesis. Photosynthesis initiates the generation of adenosine triphosphate in the chloroplast's stroma. Stroma is a semi-fluid substance that fills the space around the thylakoid stacks and stromal lamellae.
The matrix of mitochondria contains a chain of respiratory enzymes. These enzymes are unique to the mitochondria. They convert pyruvic acid and other small organic molecules into ATP. Impaired mitochondrial respiration may coincide with heart failure in the elderly.