photosynthesis and translocation Flashcards
what is photosynthesis
a process that converts light energy into biochemical energy whihc is then used to drive the assimilation of low energy inorganic carbon into high energy organic biochemicals
what are some photoautotrophic organics
prokaryotes= some bacteria e.g cyanobacteria
eukaryotes = alage, bryophytes, vascular plants
what are the characteristics of photosynthesis in green plants
1) chloroplasts containing grana and stroma
2) primary pigment chlorophyll a
3) accessory pigments such as chlorophyll b and carotenoids
how does chlorophyll a make photosynthesis possible
it passes its energised electron on to molecules which manufacture sugars
what are accessory pigments
pigments which cant transfer energy directly to the photosynthetic pathway so must pass absorbed energy to chlorophylla
what does the light phase of photosynthesis take place
photosystems embedded in the thylakoid membranes
what does the light phase of photosynthesis take place
photosystems embedded in the thylakoid membranes
where does the dark phase of photosynthesis take place
the soluble matrix of the stroma
what are photons
particles of light each containing quantum enegry which are absorbed by pigments causing them to become energised
what is photosynthetically active radiation (PAR)
the part of the spectrum which drives photosynthesis which is measured in a flux of photons
what is PFD
photon flux density which is the measure of a flux of protons which measures the part of the spectrum which drives photosynthesis
what are xanthophylls
yellow pigments which form one of two major division in the carotenoid group, the other being carotenes
what are anthocyanins
water soluable vacvuolour pigments which appear red, purple or blue depending on PH
what is formed in the light phase
1) light energy is absorbed by accessory pigments and funnelled to the reaction centre of an antenna complex
2) this drives the production of ATP and NADPH
3) oxygen is also formed during this phase
what occurs in the dark phase
the use of ATP and NADPH formed during the light phase is used in a series of enyzme catalysed reactions to assimilate carbon dioxide into a high energy organic form
what are the 4 protein complexes which contorl electron and proton transfer in the thylakoid membrane
1) PSI
2) PSII
3) cytochrome b6f
4) ATP synthase
what is water used for in the thylakoid membrane
it is oxidised producing oxygen and hydrogen ions
outline the movement of electrons through PSI and PSII
1) electron flow from reaction centrein PSII though the Z scheme via the PQ electron carrier
2) flows through the cytochrome complex to plastocyanin electron carrier to PSI
3) movement through the z scheme generates ATP enegry and NADPH reducing power
what is PQ and PC
electron carriers
what is non-cyclic photophosphorylation
When ATP is generated in an open electron transfer system linked with oxygen evolution in PSII (from photolysis), electron transfer to PSI resulting in NADPH formation
what is cyclic photophosphorylation
ATP is generated in a closed system as electrons are cycled from ferredoixn to PQ (plastoquinol) and then back to PSI via the cytochrom complex
what is the cytochrome complex
an enyzme found in the thylakoid membrane which catalyses the transfer of electrons from plastoquinol to plastocyanin
what are the three different types of photosynthesis in plants and how do they differ
1) C3 = most plants
2) C4= mostly plants of arid climates
3) crassulacean acid metabolism= mostly cacti and succulents
all differ in terms of carbon dioxide fixation biochemistry
all three involve the calvin cycle
outline the calvin cycle phases
1) fixation= carboxylation where co2 is linked to a carbon skeleton using RUBISCO forming 6c moleucle
2) reduction- 6c reduced using ATP and NADPH forming 6 3c GP moleucle
3) regeneration = 5 of the GP moleuccles used to regenrrated RuBP
