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Cholorplasts
Structure: Chloroplasts contain a permeable outer membrane and inner membrane that regulates the passage in an out of the chloroplast of small molecules like sugars and proteins in the cytoplasm. In the inner membrane, there's a complex mix of enzymes and water. This is called stroma. Embedded in the stroma is a complex structure of stacked sacs. Each stack is called a granum and each of the flattened sacs which make up the granum is called a thylakoid. Each thylakoid has a series of photosystems and associated proteins. The photosystems contain chlorophyll and other pigments. These structures in the thylakoid membrane are the site for the light reactions in which light energy is converted to chemical energy needed for the Calvin cycle.
Chloroplasts are plastids, which are organelles that are surrounded by a double membrane and contain their own DNA. They are found in plant cells and eukaryotic organisms that conduct photosynthesis.
Function of chloroplasts: - Use light energy to make carbohydrates from carbon & water. This happens by a process called photosynthesis . Using chlorophyll, plants convert the sun's energy into storable form in ordered sugar molecules such as glucose.. In this way, carbon dioxide from the air and water from the soil are combined to form more ordered sugar . Inside the chloroplasts, there are thykaloids that act to trap the energy from sunlight. Also thylakoid membranes contain chlorophyll and other pigments to capture light energy for two photosystems called Photosystem I and Photosystem II. In most plants, both photosystems are used in an electron transport process that yield energy in the form of ATP; zlso reduces coenzymes to the stroma of the chloroplast to be used in carbohydrates. The energy is used in the Calvin cycle to fix carbon from atmospheric CO2 and construct sugars.
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Shape: Chloroplasts are lens-shaped and variable in size though typically about 5 microns long (5 um in diameter and 2.3 um thick).
Chloroplasts
---Examples-- In plant cells and in many eukaryotic algea: -seaweed -cyanobacteria
