Photosynthesis occurs in the organelle called the chloroplast. The chloroplast contain the chlorophyll needed to capture the light energy so that it can be processed into energy and food for the plant.
Chloroplasts are made up of small sacs called thylakoid membranes. Each of these flat pancake-like membranes has photosystems set in a ray-like pattern to better capture and hold the light energy for use.
Chloroplasts are a type of plastid that circulate and move around inside the plant cells. These organelles reproduce by pinching themselves in two. This process occurs when a plastid dividing ring forms around the center of the chloroplast, then slowly begins to add pressure to the organelle until it splits under the ring leaving two chloroplast where there had been only one.
Chloroplasts cannot be made by the plant cell; instead, organelles must be inherited by each daughter cell during division. The chloroplast contains its own DNA, sometimes referred to as ctDNA or cpDNA, or plastome.
All of the genetic information is contained in one ring anywhere between 120,000 and 170,000 base pairs long. The chloroplast DNA was first proven to exist in 1962, but was not sequenced until 1986 by two Japanese research teams. Most of the DNA sequencing that has occurred for this comes from land plants or algae.