Photosynthesis Flashcards
The anatomy of a chloroplast
outer envelope, inner envelope, stroma, granal thylakoid, stromal thylakoid
What happens in photosystem II?
Chlorophyll molecules take in light and focus this energy on the primary pigment molecule. This chlorophyll molecule is so high energy that it loses one of its electrons making it chlorophyll+. The chlorophyll+ rips an electron from a water molecule which splits it into oxygen and hydrogen ions
What happens after photosystem II?
Electron from photosystem II is passed along the electron transport chain to photosystem I and is added to another primary pigment molecule where energy is focused to give the electron more energy. The high energy electron is able to leave photosystem I so NADP can be reduced to NADPH
What is the role of NADPH?
Oxidised forms of the elements can be reduced so they become more reactive so complex organic molecules can be made.
Carbon dioxide to carbohydrates
Nitrate to amines for amino acids and sulphate to sulfide groups for the making of lipids.
How is ATP made in the light dependant reaction?
H+ ions are trapped inside the thylakoid membrane because they’re charged. This creates an electrochemical gradient in the membrane. The difference in acidity between the outside and inside of the thylakoid membrane is used to drive the protein ATP synthase which can then synthesise ADP to ATP.
What is the importance of ATP?
This energy is required so NADPH can reduce inorganic molecules into organic molecules for the plant to use.
What are manganese atoms used for?
Manganese atoms are required for the splitting of H2O so the electrons can be released.
What is the role of ferrodoxin?
Ferrodoxin reduces NADPH to produce the reducing molecule that’s needed to synthesis inorganic molecules.
Describe what happens during ATP synthase
ATP synthase is made up of a complex of proteins and is driven by the electrochemical gradient on the thylakoid membrane from the build up of protons. The flow of protons causes the ATP synthase to spin, as it spins a buldge located on the stalk knocks the proteins in and out. As this happens ADP and phosphate molecules are drawn into ATP synthase and are joined together to make ATP.
Where does ATP synthase take place?
Thylakoid membrane and stroma
What enzyme catalyses the fixation of carbon dioxide?
Rubisco
Why is rubisco important?
Fixes 18% of atmospheric CO2 and is nutritionally important for herbivores.
Describe the calvin cycle
Rubisco fixes carbon dioxide to ribulose biphosphate (5Cx3) to make phosphoglycerate (3Cx6). This molecule is then reduced using NADPH and ATP to make triosphosphate (3Cx6). One of the triosphosphate molecules leaves the calvin cycle and is used in the synthesis of sucrose. (Triosphosphate (3Cx5). Over the regeneration period ATP is used to re shuffle the carbon back to ribulose biphosphate (5Cx3).
What is the affect on plants of concentration of CO2 increases?
The stomata which are pores where CO2 diffuses through to be fixed in the calvin cycle stay open for a shorter amount of time. This means less water is loss and put into the atmosphere which reduces the atmospheres heat capacity and dries up the rivers.
