Functions: Mitochondria are miniature biochemical factories where food is oxidized and energy is released. This energy is stored in the form of ATP. Hence, mitochondria are called powerhouse of the cell. Oxidizes pyruvic acid (breakdown product of glucose) to release energy which gets stored in the form of ATP for ready use. This process is also called cellular respiration. Synthesis of many amino acids occurs in mitochondria.
Plastids are cell organelles found only in plant cell. Plastids contain many membrane layers embedded in a material called the stroma. There are three types of plastids; chromoplasts (coloured plastids), chloroplasts (green) and leucoplasts (white or colourless plastids).
Contain red, orange or yellow pigments (other than green), non-photosynthetic and give colour to fruits and flower.
Colourless plastids lack any pigment, non-photosynthetic and store nutrients like starch and oil drops abundant in seeds and starch grains.
They are green plastids, photosynthetic green pigment, i.e. chlorophyll. They also contain various yellow or orange pigments in addition to chlorophyll. Each chloroplast is covered by a double layered unit membrane. The two membranes are separated by an intermembrane space. Inside the inner membrane, chloroplasts have a matrix or stoma and disc like bodies called grana.
Functions: Chloroplasts, the green plastids, help in photosynthesis and thus, help in the synthesis of food. These are called kitchen rooms of the cell.
Mitochondria are involved in cellular respiration whereas chloroplasts are involved in photosynthesis. So the chemical reactions for the processes occurring in them are different and reversed.
Chloroplasts contain pigments such as chlorophyll a, chlorophyll b and carotenoids. Mitochondria do not contain any such pigments.
Mitochondria are found in all animal and plant cells while Chloroplasts are found in only specific types of plant cells.
Mitochondria and chloroplast both have double membrane surrounding the organelles.
Their own circular DNA which codes for certain enzymes required for the chemical reactions that take place in these organelles.
Their own 70S ribosomes made up of 50S and 30S subunits to translate proteins.
Since chloroplasts and mitochondria contain their own DNA the hereditary molecule and also their own ribosomes, they are termed semi-autonomous only because they are incapable of independent existence though they have ribosomes and DNA.