What are the process occurs in photosynthesis? How starch is synthesize?
THYLAKOID Chloroplast Dark reaction occurs Light reaction occurs STROMA
Light energy Chemical energy
Chlorophyll & accessory pigments absorb slightly different color of light and pass its energy to central chlorophyll molecule (Chlorophyll a) to do photosynthesis.
Two forms of chlorophyll a molecules
P700 in PSI (700 nm)
P680 in PSII(680 nm)
Role of Photosystem
:Provide sufficient energy to boost the photoactivated electron to an energy level high enough accepted by NADP
: pump proton across thylakoid membranes.
Photosynthesis: Pathway of Carbon Fixation STARCH
CO2 combines with the phosphorylated 5-carbon sugar ribulose bisphosphate (RUBP) reaction is catalyzed by the enzyme ribulose bisphosphate carboxylase oxygenase ( RUBISCO ) resulting 6-carbon compound breaks down into two molecules of 3-phosphoglyceric acid ( PGA ). PGA molecules are further phosphorylated (by ATP ) and are reduced (by NADPH ) to form phosphoglyceraldehyde ( PGAL ). Enzyme responsible for fixing 200 bilion tons of CO2 anually
Phosphoglyceraldehyde (PGAL) serves as the starting material for the synthesis of glucose and fructose . Glucose and fructose PolysaccharideSynthesis starch & cellulose Travel to other part of the plant As Monomer Sucrose
CO2 + H20 3-phosphoglycerate ATP + NADPH ADP + Pi NADP+ Triose Phosphate Sucrose, Starch ATP ADP CARBOXYLATION REDUCTION REGENERATION
Equation of sugar glucose
6CO2 + 12H2O C6H12O6 + 6H2O + 6O2
CH2O~P Chlorophyll H20 O2 CH2O~P H20 CO2 + H2O ( CH2O)n ATP [ADP + Pi], NADP+ + NADPH Light
Reduction Process in Calvin cycle
Adds a phosphate from ATP to the 3-PGA
removes hydrogen from NADPH and adds it to the 1,3-bisphosphoglycerate
In this reduction, a phosphate is removed
resulting NADP+, ADP, and Pi can be recycled to the light reactions
These steps demonstrate why the light reactions and Calvin cycle are interdependent
Why convert Glucose to Starch?
products of photosynthesis are assembled in plant to make glucose
Glucose (C 6 H 12 O 6 ) is a monosaccharide or single sugar
plant uses glucose as short-term energy storage
converted into a polysaccharide called starch, allowing the plant to store most of the energy collected in photosynthesis in the chemical bonds between the sugars
When the plant needs energy, the bonds holding the glucose molecules together are broken, and energy is released
Starch is a better way to store energy because it has more bonds to hold potential energy and it can be stored in large amounts without disturbing the rest of the plant.