Photosynthesis Flashcards
where do LDR and LIR occur in plants
LDR occur in the thylakoids of chloroplasts.
LIR occur in the stroma of chloroplasts.
photoionisation
chlorophyll absorbs energy from photons of lights.
this excites electrons (raises them to a higher energy level) which releases them from the chlorophyll.
electron transfer chain (ETC)
electrons released by chlorophyll move down a series of carrier proteins embedded in the thylakoid membrane and undergo a series of redox reactions, which release energy.
photophosphorylation
process of utilizing light energy from photosynthesis to convert ADP into ATP.
chemiosmosis
energy from excited electrons in ETC is used to actively transport H+ ions into thylakoid space from the stroma, creating a concentration gradient.
the protons diffuse down their concentration gradient via channel protein ATP synthase.
ATP synthases catalyses ADP to ATP.
production of reduced NADP in LDR
PSI accepts the electrons that came from PSII, they are excited by light and move through more electron carrier proteins.
Electrons are taken up by NADP along with protons (from photolysis) to form reduced NADP.
catalysed by dehydrogenase enzymes.
photolysis of water
light energy splits molecule of water.
2H2O–>4H+ + 4e- + O2
functions products of photolysis of water
H+: move out of thylakoid space via ATP synthase and are use to reduce NADP.
e-:replace electrons lost from chlorophyll
O2: used for respiration or diffuses out of leaf as waste gas.
3 main stages of calvin cycle
carbon fixation
reduction
regeneration
carbon fixation
-CO2 enters the leaf through stomata.
-CO2 reacts with RuBP catalysed by enzyme rubisco producing an unstable 6C compound.
-The 6C compound breaks into 2 molecules of glycerate 3-phosphate (GP).
reduction
the 2 GP molecules are reduced into 2 TP (triose phosphate) which require 2 ATP from LDR to provide energy.
requires 2 reduced NADP .
forms 2 NADP and 2 ADP.
use of TP
converted to useful organic compound- to build complex carbohydrates, amino acids and lipids.
regeneration
5 out of 6 molecules of TP produced are used to regenerate 5C compound RuBP.
the rest of the ATP produced in the LDR is also used regenerate RuBP, forming ADP.
how does structure of chloroplast maximise rate of LDR
-ATP synthase channels -within granal membrane.
-large surface area for thylakoid membrane for ETC.
-photosystems position chlorophyll to enable maximum absorption of light.
how does structure of chloroplast maximise rate of LIR
own DNA and ribosomes for synthesis of enzymes e.g. rubisco.
concentration of enzymes and substrates in stroma is high.
