5.6 photosynthesis Flashcards
autotroph
produce their own energy
general FORMULA equation for photosynthesis
6CO2 + 6H2O -> C6H12O6 + 6O2
compensation point
- photosynthesis and respiration occur at same rate
how many membranes does a chloroplast have?
3
outer
inner
thylakoid
large circle in chlorplast
starch grain
where does LDR take place
thylakoid
where does LIR take place
stroma
adaptatiosn of grana
- large SA so many photosystems so max absorption of light
- more membrane space for ETC and ATP synthase enzymes
chloroplast DNA
- naked circular DNA not associated w histones
- used to make some of the proteins and enzymes for phot
chloroplast ribosomes
70s ribosomes allows for translation of proteins coded for by cpDNA
2 different types of chlorophyll a
- p680
- p700
p680 is in PS…
2
P700 is in PS…
1
accessory pigments
- carotenoids (reflect yellow orange)
- xanthophylls (reflect yellow)
what can you use to separate photosumthestic pigments
TLC
where does photolysis occur
PS2
Photolysis
- PS2
- splitting of water
2h20 = 4h+ + 4e- + o2
how is oxygen produced in LDR? and what happens
- photolysis of water at PS2
- diffuses out through stomata
- used for respiration
2 uses of water (ps)
- source of h+ used for photophosphorylation
- donates e- to chlorphpyll to replace those lost
non cyclic phosphorylation involves…
ps1 AND ps2
cyclic phosphorylatin involves…
ps1
STEPS of ldr (non cyclic)
- photon of light strikes PS2 (p680), energy is channelled from light harvesting centre accessory pig to primary pigment reaction centre
- light energy excites a pair of electrons in the chlorophyll a
- energised electrons escape chlorophyll and are captured by an electron carrier embedded in the thylakoid membrane
- ELECTRONS LOST TO ETC REPLACED BY PHOTOLYSIS IN PS2
- e- passed down etc in a series of reduction oxidation
- energy is released, used to ACTIVELY PUMP protons across the t membrane into the t space
- protons accumulate in the t space, proton gradient formed
- protons diffuse down CG through ATP synthase channels. proton motor force causes adp + pi -> atp
- electrons from etc and these protons are then taken in by ps1. excited, etc, same thing
- protons and eectrons from PS1 are accepted by NADP to reduce it to NADPH ,(NADP REDUCTASE ENZYME)
CYCLIC PHOSPHORYLATION
- light striked PS1 so ONE ELECTRON become excited and do the ETC stuff
- NO PHOTOLYSIS OF WATER, so no h+ or o2 produced
- no NADPH made
ONLY PRODUCT IS ATP
chloroplasts in guard cells
- only do cyclic, only have PS1
- produce only ATP which brings in k+ to cells so water will enter by osmosis