photosynthesis
chemiosmosis
Pi + ADP = ATP
Stack of thylakoids
granum
stroma
space inside a chloroplast
things in a chloroplast
thylakoid membrane
thylakoid space
granum
stroma
stsarch grain
outer membrane
inner membrane
dna loop
main/primary pigment
chlorophyll
chlorophyll absorbs/reflects:
absorb: red and blue light
reflect: green light
accessory pigments
photosynthetic pigments that absorb different wavelengths of light to increase the range of light energy absorbed
accessory pigment examples
Chlorophyll B
xanthophylls
carotenoids
beta carotene
photosystems
The actual structures embedded in the thylakoid membrane that contain photosynthetic pigments used to absorb a wide range of light wavelengths
reaction Centre contains
Chlorophyll A
Energy from all pigments is used
Excite two electrons so they can be released to a higher energy level
light dependent reaction products
2 ATP
Reduced NADP
where do LDR and LIR reactions take place?
LDR: thylakoid membrane
LIR: stroma
two types of LDR
Cyclic photophosphorylation
Non-cyclic photophosphorylation
cyclic photophosphorylation process
1. e- in ps1 are excited by light energy
2. e- escape and are taken in by primary electrom acceptor
3. e- pass down ETC and lose energy
4. energy is used to pump H+ iond across thylakoid membrane
5. this creates electrochemical gradient so H+ diffuse back through ATP synthase. this produces ATP from ADP+ Pi (chemiosmosis)
6. e- eventually fall back into ps1
non-cyclic photophosphorylation
1. light excites e- in both photosystems
2. from ps11 e- are taken in by primary electron acceptor
3. e- pass down ETC and lose energy
4. energy is used to pump H+ ions across thylakoid membrane and create electrochemical gradient
5. H+ ions diffuse back through ATP synthase to produce ATP
6. e- are taken in by ps1
7. from ps1 e- go to electron acceptor, then ETC, then used to make reduced NADP
8. photolysis of water (happening at same time): H2O = 2H+ + 2e- + 1/2 O2
9. H+ used to make reduced NADP, 2e- used to give to ps11, O2 is released
light independent reaction/calvin cycle
1. CO2 added to 5-carbon molecule RuBP to produce unstable 6-carbon intermediate molecule (reaction is called carbon fixation and is catalysed by RUBISCO (enzyme))
2. unstable intermediate molecule breaks into 2 3-carbon molecules called GP. ATP and reduced NADP are used to convert GP into TP (reduction stage). TP is converted into amino acids, fattu acids, glycerol, hexose sugars
3. ATP is added to some TP molecules to regenerate 5-carbon RuBP
limiting factor
Usually lead to an increase in the rate of photosynthesis
Temperature
Light intensity
Carbon dioxide conc
light intensity
As intensity increases rate of photosynthesis also increases
This will increase until another factor is limiting
light intensity (LDR/LIR)
If light intensity is lowered, It will limit concentrations of ATP in reduced NADP
With less ATP and reduced NADP there will be less conversion of GP to TP and less TP to RuBP
Concentration of GP will increase, but TP and RuBP will decrease
temperature
As temperature increases rate of reaction will increase due to increased kinetic energy
Above the optimum temp proteins will lose their tertiary structure and denature
All of Calvin cycle reactions are controlled by enzymes so denaturing will mean no carbon fixation and no conversion of GP to TP or TP to RuBP
carbon dioxide concentration
Higher CO2 concentrations will lead to higher rate of fixation
This will lead to a higher concentration of GP and TP
compensation point
The points were the rate of carbohydrates produced by photosynthesis are balanced by the rate of carbohydrates consumed by respiration
Two during each day
graph- photosynthesis and respiration meet