Chloroplast and Photosynthetic Structures

Labelled parts

1. 1Light directionLight arrives from the sun and is absorbed by chlorophyll in the thylakoids.
2. 2Outer chloroplast membraneThe outer boundary of the double-membrane envelope; it lets small molecules pass.
3. 3Double-membrane envelopeTwo membranes surround the organelle, a clue to its bacterial origin.
4. 4GranumA stack of thylakoid discs, like a pile of coins, where the light reactions happen.
5. 5Thylakoid stackStacking packs a large area of membrane and chlorophyll into a small volume.
6. 6Stroma lamellaeUnstacked thylakoid membranes that connect one granum to the next.
7. 7StromaThe fluid where the Calvin cycle builds sugar from carbon dioxide.
8. 8Circular chloroplast DNAThe organelle's own small circular genome, much like a bacterium's.
9. 9Starch granuleTemporary storage of sugar made during the day.
10. 10Oxygen releaseOxygen is a by-product, released when water is split in the light reactions.