Post on 24-May-2015
transcript
What are the process occurs in photosynthesis?
How starch is synthesize?
THYLAKOID
ChloroplastDark reaction occurs
Light reaction occurs
STROMA
Light Reactiono Light energy Chemical energyo Chlorophyll & accessory pigments absorb
slightly different color of light and pass its energy to central chlorophyll molecule (Chlorophyll a) to do photosynthesis.
o Two forms of chlorophyll a molecules(a)P700 in PSI (700 nm)(b)P680 in PSII(680 nm)o 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.
Non-cyclic photophosphorylation
Cyclic Photophosphorylation
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
CARBOXYLATION
REDUCTION
REGENERATION
CO2 + H20
3-phosphoglycerate
ATP + NADPH
ADP + Pi NADP+
Triose PhosphateSucrose, Starch
ATP
ADP
Equation of sugar glucose
6CO2 + 12H2O C6H12O6 + 6H2O + 6O2
CH2O~PChlorophyll
H20
O2
CH2O~P
H20
CO2 + H2O
(CH2O)n
ATP
[ADP + Pi], NADP+
+ NADPH
Light
Reduction Processin 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 (C6H12O6) 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.