mechanism of photosynthesis
TRANSCRIPT
Photosynthesis Song!
6.11 The Mechanism of Photosynthesis
Text Book page 133
Watch chloroplast in 3D!
Watch chloroplast in 2D!
Structure of a chloroplastStarch granuleStorage of insoluble products of photosynthesis
Chloroplast envelopePermeable to glucose, ions, O2 and CO2
Thylakoid
Granum•Stacks of thylakoid membrane•Important in ATP synthesis•Site of light reaction
Stroma•Is a gel-like matrix•Site of dark reaction
Lipid droplet
Light Reaction In Granum
Photolysis of water
water
24OH-
24e- 24OH
6O212H2O
chlorophyll24e-24H
24H+
24H2O
Sunlight
Dark reaction in stroma
1. Chlorophyll absorbs sunlight and produces energy. Energy activates the water molecules to dissociate into H+, OH- and e-
Neutral hydroxyl groups combine together to form water and O2
2. Chlorophyll becomes excited and releases e-
3. Each H+ receives an e- from the chlorophyll and is neutralised to form a neutral hydrogen atom (H)
Quick check!
Dark Reaction in Stroma
6CO2
6(CH2O) +
C6H12O6
Starch
6H2O
Released to atmosphere
(Glucose)
4. Hydrogen atoms (H) are used in dark reaction to fix CO2 which is catalysed by photosynthetic enzymes.
6 units of CH2O will combine to form a molecule of glucose.
condensation
Protein Lipids
Quick check!
SPM Clone Question!
Light reaction
Light reaction
R
Q
Light energy
glucose water+
What do P, Q and R represent?
Answer:P = Hydrogen atomQ = oxygenR = carbon dioxide
P
Water + Carbon dioxide Glucose + Oxygen
6H2O 6CO2
Light
Chlorophyll C6H12O6 6O2
SPM Clone Question!
Carbon dioxide + X Glucose Y+
What are X and Y?
Answer: X = water , Y = oxygen
SCHEMATIC DIAGRAM OF PHOTOSYNTHESIS
Photosynthesis
Light Reaction Dark Reaction
Chlorophyll sunlight
Water (H2O)
Hydrogen ions (H+)
CO2Hydrogen (H)
Hydroxide ions (OH-)
Hydroxyl groups (OH)
O2 H2O
Basic glucose units (CH2O)Water (H2O)
Glucose (C6H12O6)
Air / Atmosphere Proteins Lipids Carbohydrates
requires
absorb
Breaks up
combines
forms
Absorb e-
split
Release e-
goes
Comparison between light and dark reactions
Similarities
Differences
As to conclude, watch this!
As to conclude, do this!
1. Define photosynthesis. (2 m)
2. Photosynthesis occurs as a string of chemical reactions. Explain how photosynthesis happens in green plants. (8 m)
Thank you for your attention!
Hehehehe….