Class Notes

Chloroplast Chloroplast is the structure in the cells of plants and some other organisms that captures energy from sunlight and uses it to produce food. Chloroplast gives plants its green color, because it has Chlorophyll in it, which has green pigment in it to give it the color. Plants or fruits with color in it have something in it called Chromoplast. Chromoplast has pigment in that gives fruits and plants its color, it also has traces of chlorophyll, which gives the bottom or top of the plant its green portion. The chlorophyll is found in the thlakoids of the organelle Chloroplast is made up of the stroma, thylakoid, granum, membrane(inner and outer), and Stromal Lamellae. The stroma is like the cytoplasm of the chloroplast. It keeps everything in place. It is also the framework of the organelle. The thylakoids are disk shaped membranous sac containing chloraphyll in which the light reaction of photosynthesis occurs, found in blue-green algae and in the chloroplast of green plants. The granum is a stack of thylakoids. The outer membrane is permeable,unlike the the inner membrane which is less permeable. AS we mentioned before the Chlorophyll in the chloroplast gives it the green color, but the pigment in it is why the plant is green, but it also absorbs green light. Absorbing the green light gives the plant its green color. If the pigment reflected all the colors the plant would be white. The green color is reflected in your eyes and that’s why it looks green to us. So the color that the pigment reflects is the color of the object. Photosynthesis is the process by which plants and some bacteria use the energy from the sunlight and converts it into sugar that can be used by the cell. Then cellular respiration converts into ATP (adenosine tri phosphate), which is like the cells “fuel.” Cellular respiration is the transfer of energy from various molecules to produce ATP. This process occurs in the mitochondria of eukaryotic cells and in the cytoplasm of prokaryotic cells. How do scientist think that chloroplast came to be?( we may need help explaing this by Mr. Karrer) Well anyway the Serial Endosymbiotic Theory was postulated based on studies of both prokaryotic and eukaryotic cells. Two of the main organelles that have facinated biologists and bontanists is the mitochondria and chloroplasts. The reason why is they are very simular to prokaryotic cells. What is also interesting about both is they have their own DNA and they divide and reproduce without help from the cell they are living in. It is important to note they can not live on their own but its pretty clear they are like prokaryotic cells. So the theory is that Prokaryotic cells used to live in a vey harsh environment and were unable to make their own food so they had to engulf everything to get the nutrients they needed. Well when they were engulfing stuff sometimes they engulfed their fellow cells. The idea is that one or more of these fellow prokaryotic cells managed not to be digested by the cell but instead helped the cell out which cause the cell not to want to eat it. Basically a mutual symbiotic relationship was born. It is believed that the first cells that were engulfed were free-living bacterium that were evolutionarily very simular to the mitochondria we have today. The reason it is believed that mitochondria came first is all eukaryotic cells have mitochondria but not all eukaryotic cells have chloroplasts

http://micro.magnet.fsu.edu/cells/chloroplasts/chloroplasts.html http://www.biology4kids.com/files/cell_chloroplast.html http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chloroplasts.html http://library.thinkquest.org/C004535/chloroplast.html