noun, plural: plastids
A double membrane bound organelle involved in the synthesis and storage of food, and is commonly found within the cells of photosynthetic organisms, like plants
One of the distinctive features of a plant cell is the presence of plastids. A plastid is a cytoplasmic organelle involved in the synthesis and storage of food. Its function largely depends on the presence of pigments. A plastid involved in food synthesis typically contains pigments, which are also the ones responsible for the color of a plant structure (e.g. green leaf, red flower, yellow fruit, etc.).
A plastid containing green pigment (chlorophyll) is called chloroplast whereas a plastid containing pigments apart from green is called a chromoplast. A plastid that lacks pigments is called a leucoplast, and is involved mainly in food storage. A leucoplast may be an amyloplast that stores starch, an elaioplast that stores fat, or a proteinoplast that stores proteins. An undifferentiated plastid is called a proplastid. It may develop later into any of the above-mentioned plastids.
Like mitochondria, plastids have their own DNA and ribosomes. Hence, they may be used in phylogenetic studies.
Word origin: Greek plastide, from plástis, plástés (“modeler, creator”), from plássein (“to form”)