|Chloroplasts ... double membrane bound organelle in plants, responsible for photosynthesis, oxygen evolution and CO2 reduction (dark reactions).
number per cell = roughly 50
shape is variable: oblate spheroid, stellate, reticulate, etc...
size: 2-3 microns by 5-10 microns
contents include contents a liquid STROMA (chloroplasm) that holds:
1) 70s ribosomes (bacterial size)
2) lipid droplets
3) naked DNA pieces (supercoiled & repetitive)
4) starch granules (pyrenoids)
5) enzymes of CO2 fixation (reduction)
and an internal membrane system of THYLAKOID membranes, which
enclose a lumen. Stacked arrays are called GRANA (resembling a
stack of coins).
Four types of protein assemblies are embedded in the thylakoids
Photosystem I which makes NADPH
Photosystem II which which splits water & makes ATP
ETC components as Cytochromes b and f
These assemblies carry out the light reactions of photosynthesis.