3.5.j PHOTOSYNTHESIS
Life depends or continuous trans fers ot enerqy. ln plants, eneray
Light is absorbed by chlorophyll then Erans terred nto chemical
in the
cnerqy. chloroplasts are the cellular orgoneles in leat where
photosynthes1s occuts.
Leat Adaptat1ons
- Large surtace area
- Thin short dittusion distance
Transparent cutde and epiderm1s
- stomata for gas exchange
- Air spaces - capid ditfusion
- Xylem ond phloem
Structure and tuncton ot chloroplasts
-double membrane -co nopartmentalisation
Cirana - stacks of thulakods
site ot Liaht-dep2ndant staqe
Intecaranad lamelae
Stroma - flud tiled matx
bsite ot Lght -independent stage
s
Photosunthesis Lomplex metabouc pathway invalving many
where
untemediate reactions. IE's a process of enerqy transtertal
hdnds.
where SOme Liqhtenerqy IS LOnServed In chenmical
Stages ot photosyathes1s
-
Laptucing ot Light encrgy
Light-dependent reaction
- Lignt-independeat reaction
, LIGHT DEFENDLNT STAGE
Copture ot Light energy
Photolssis ot wate nto protons and 0H ions
Oxidation- Loss ot hudrogen, loss ot electrons, gain of oxygen
Keduction gain of hydrogen, 4ain of clectrons, Loss of oxygen
Mak1ng ot ATP
when a chlorophyl molecule absorbs lght eneqy, t excites opair
of electOns, which leaves the molecule - photoionisation.
The eletons pass alng edectron catiers n a seces of edox
reachons. Ihe tanster chawn is located in the membane of thylakoids
L
energy lost down the electron transter chainisused to make
Some ATP trom ADP and Pi
Chemosmotc Theony
Each thylakoid is an endosed chamber nto whIch protons ae
pumped tom stoma by carrier protens
’the enerqy for this comes trom electons released in
photolysis ot water
photolys1s ot water also produces protons which tucther reases
taer concentratin n the thylakoid spa.
- Protons can
ony pras from thylakod to stroma through ATp
synthase protens (stalked qranules)
As protons pass through, they caange the shape ot
enzyme to catalyse ÅDP p.’AP the
Photolyss ot Lwater
2H,0
These electrons eplace the ones lost from
htorophyl moleules. photonisatign ot
The protons pass thro ugh ATP synthasc and
NADP H NADPH H ae taken up by NA DP
The oxuygen is used in
respirotion or d1ttused out ot the leat
Site ot light dependent reaction
hylakod membrone provides a large Surta area
Protein nelwok holds chiorophyll
Chloroplasts contoin both DNA precisely fo meXIMISe
-
SOme usetw proteins nd ibosomes to absorpticn
manutactu
Life depends or continuous trans fers ot enerqy. ln plants, eneray
Light is absorbed by chlorophyll then Erans terred nto chemical
in the
cnerqy. chloroplasts are the cellular orgoneles in leat where
photosynthes1s occuts.
Leat Adaptat1ons
- Large surtace area
- Thin short dittusion distance
Transparent cutde and epiderm1s
- stomata for gas exchange
- Air spaces - capid ditfusion
- Xylem ond phloem
Structure and tuncton ot chloroplasts
-double membrane -co nopartmentalisation
Cirana - stacks of thulakods
site ot Liaht-dep2ndant staqe
Intecaranad lamelae
Stroma - flud tiled matx
bsite ot Lght -independent stage
s
Photosunthesis Lomplex metabouc pathway invalving many
where
untemediate reactions. IE's a process of enerqy transtertal
hdnds.
where SOme Liqhtenerqy IS LOnServed In chenmical
Stages ot photosyathes1s
-
Laptucing ot Light encrgy
Light-dependent reaction
- Lignt-independeat reaction
, LIGHT DEFENDLNT STAGE
Copture ot Light energy
Photolssis ot wate nto protons and 0H ions
Oxidation- Loss ot hudrogen, loss ot electrons, gain of oxygen
Keduction gain of hydrogen, 4ain of clectrons, Loss of oxygen
Mak1ng ot ATP
when a chlorophyl molecule absorbs lght eneqy, t excites opair
of electOns, which leaves the molecule - photoionisation.
The eletons pass alng edectron catiers n a seces of edox
reachons. Ihe tanster chawn is located in the membane of thylakoids
L
energy lost down the electron transter chainisused to make
Some ATP trom ADP and Pi
Chemosmotc Theony
Each thylakoid is an endosed chamber nto whIch protons ae
pumped tom stoma by carrier protens
’the enerqy for this comes trom electons released in
photolysis ot water
photolys1s ot water also produces protons which tucther reases
taer concentratin n the thylakoid spa.
- Protons can
ony pras from thylakod to stroma through ATp
synthase protens (stalked qranules)
As protons pass through, they caange the shape ot
enzyme to catalyse ÅDP p.’AP the
Photolyss ot Lwater
2H,0
These electrons eplace the ones lost from
htorophyl moleules. photonisatign ot
The protons pass thro ugh ATP synthasc and
NADP H NADPH H ae taken up by NA DP
The oxuygen is used in
respirotion or d1ttused out ot the leat
Site ot light dependent reaction
hylakod membrone provides a large Surta area
Protein nelwok holds chiorophyll
Chloroplasts contoin both DNA precisely fo meXIMISe
-
SOme usetw proteins nd ibosomes to absorpticn
manutactu
