Plastids are doubled membraned 'sac-like' organelles, generally involved in either the manufacture or storage of food. They include chloroplasts, chromoplasts and leucoplasts All develop from proplastids: simple, generally colorless undifferentiated plastids. 1. Chloroplasts: Number: may range from a few in algae to 75-125 in angiosperm cells. Functions-a. photosynthesis thus they contain chlorophyll, carotenoids in the thylakoids b. as they contain ribosomes, they are involved in amino acid and protein sythesis.This is not surprising considering the enzyme RUBP involved in photosynthesis can make up 50% of the total protein in a leaf extract analysis. 2. Chromoplasts are found commonly in flowers and fruits. They contain yellow, orange and or red pigments... carotenoids Function? they convey information or serve as attractants. In fruits, these colors signal that the fruit is ripe ( as is the embryo), starches have converted to sugars and the bond that holds the cells together digesting to produce a softer texture. Most organisms recognize that 'green' means hold off. They also serve as attractants and identifiers... a fast moving potential pollinator has little time to site a flower.. the brighter, the more distinguishable, the more likely it will be visited. In some cases, the flower will change color to signal it has already been pollinated and nectar is no longer available. Leucoplasts are non-pigmented plastids involved in either synthesis or storage Amyloplasts: starch production Elaioplasts: oil production

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