Plant chloroplasts are commonly found in guard located in plant . Guard cells surround tiny pores called , opening and closing them to allow for gas exchange required for photosynthesis. Chloroplasts and other plastids develop from cells called proplastids. Proplastids are immature, undifferentiated cells that develop into different types of plastids. A proplastid that develops into a chloroplast, only does so in the presence of light. Chloroplasts contain several different structures, each having specialized functions. Chloroplast structures include:
Parenchyma Cells Are Living Cells That Have Diverse Functions Ranging From Storage and Support to Photosynthesis and Phloem Loading Transfer Cells will be available on
the function is storage, photosynthesis, ..
In , the sun's solar energy is converted to chemical energy. The chemical energy is stored in the form of glucose (sugar). Carbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water. Photosynthesis occurs in two stages. These stages are known as the light reaction stage and the dark reaction stage. The light reaction stage takes place in the presence of light and occurs within the chloroplast grana. The primary pigment used to convert light energy into chemical energy is chlorophyll a. Other pigments involved in light absorption include chlorophyll b, xanthophyll, and carotene. In the light reaction stage, sunlight is converted to chemical energy in the form of ATP (free energy containing molecule) and NADPH (high energy electron carrying molecule). Both ATP and NADPH are used in the dark reaction stage to produce sugar. The dark reaction stage is also known as the carbon fixation stage or the Calvin cycle. Dark reactions occur in the stroma. The stroma contains enzymes which facilitate a series of reactions that use ATP, NADPH, and carbon dioxide to produce sugar. The sugar can be stored in the form of starch, used during , or used in the production of cellulose.