Light Dependent Reacrions Flashcards
Why is photosynthesis important
Photosynthesis is important to provide a supply of organic molecules such as carbs, amino acids, lipids and nucleic acids which are needed by plant to survive
What are the 2 parts of photosynthesis and where do the reactions take place
2 parts of photosynthesis are light dependent reactions and light independent reactions.
LDR reactions occur in thylakoids and LIR occur in stroma
What is structure of chloroplast
Structure of chloroplast is outer membrane (permeable to 02 and H20)
Inner membrane (helps regulate entry and exit of substances)
Thylakoid membrane (system of interconnected flattened fluid filled sacs)
Thylakoid space (fluid within thylakoid membrane sacs contain enzymes for photolysis)
Granum/lamellae(stack of thylakoids joined to each other, grana plural)
Starch grain (stores excess carbs made in photosynthesis)
Stroma (fluid surrounding thylakoids which contain all enzymes needed to carry out light independent reactions )
DNA loop and ribosomes (protein synthesis)
What are the functions of light
4 functions of light are
Excites electrons, Allows photophosphorylation to occur
Excited electrons, which allows reduction of NAPD to NAPDH
Initiates photolysis of water
Triggers opening of stomata pores to allow diffusion of CO2 into leaves
What is substrate level phosphorylation
Substrate level phosphorylation is addition of phosphate to ADP.
What is photolysis
Photolysis is splitting of water into H+,e- and 02 using light energy.
What is role of NADP
Role of NADP are
Acts as H carrier
Prevents H reacting with 02
Reduced NASP carried H to be used in LIR
What happens to electrons during LDR
Electrons become excited and raised to a higher energy level and passes along a series of electron carrier molecules. Electron carriers are embedded in thylakoid membrane. Electrons pass from 1 carrier to next in a series of REDOX reactions. Electrons lose energy which is used in synthesis of ATP (phosphorylation). Electrons from PSI chlorophyll combine with coenzyme and H+ from water to form reduced NADP.
What is process of LDR
Process of LDR is
1) light energy excites electrons in chlorophyll. (They leave chlorophyll)
2) photolysis of water occurs to produce oxygen, hydrogen ions and electrons.
3) these electrons are used in ETC. To replace those lost by chlorophyll. Transported along electron carrier molecules in a series of Redox reactions.
4) Photophosphorylation occurs, generating ATP
5) NADP picks up electrons and becomes reduced NADP
What is photoexcitation
Photoexcitation is gaining light energy.
How is ATP synthesised in LDR
ATP synthesised by redox reactions, as electrons move from carrier to carrier energy is released. Used to synthesise ADP+P
