Term | Definition |
autotroph | an organism that produces its own nutrients from inorganic substances or from the environment instead of consuming other organisms |
photosynthesis | the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen |
heterotroph | an organism that obtains organic food molecules by eating other organisms or their byproducts and that cannot synthesize organic compounds from inorganic materials |
light reactions | the initial reactions in photosynthesis, triggered by the absorption of light by photosystems I and II. include the passage of electrons along the electron transport chains, the production of NADPH and oxygen gas, the synthesis of ATP through chemiosmosis |
chloroplast | an organelle found in plant and algae cells where photosynthesis occurs |
thylakoid | a membrane system found within chloroplasts that contains the components for photosynthesis |
granum | a stack of thylakoids in a chloroplast |
stroma | in plants, the solution that surrounds the thylakoids in a chloroplast |
pigment | a substance that gives another substance or a mixture its color |
chlorophyll | a green pigment that is present in most plant cells, that gives plants their characteristic green color, and that reacts with sunlight, carbon dioxide, and water to form carbohydrates |
carotenoid | a class of pigments that are present mostly in plants and that aid in photosynthesis |
photosystem | in the thylakoid membranes of chloroplasts, a cluster of chlorophyll and other pigment molecules that harvest light energy for the light reactions of photosynthesis |
primary electron acceptor | a molecule in the thylakoid membrane that is the acceptor of the electrons lost from chlorophyll A |
electron transport chain | a series of molecules, found in the inner membranes of mitochondria and chloroplasts, through which electrons pass in a process that causes protons to build up on one side of the membrane |
chemiosmosis | in chloroplasts and mitochondria, a process in which the movement of protons down their concentration gradient across a membrane is coupled to the synthesis of ATP |