Photosynthesis Flashcards
Phosphorylation
Adding phosphate to a molecule
Photophosphorylation
Adding phosphate using light
Photolysis
Splitting a molecule using light
Hydrolysis
Splitting a molecule using water
Reduced
Gaining electrons or gained hydrogen
Oxidised
Lost electrons or gained oxygen
Photosynthesis Definition
The process where energy from light is used to break H2O and store hydrogen as glucose. It occurs in the chloroplast
Photosynthesis Equation
6CO2 + 6H20 + ENERGY = C6H12O6+6O2
ATP as an Energy store
During respiration, glucose is broken down
This releases energy that creates synthesis of ATP º
How is ATP synthesise?
- Phosphorylation of ADP occurs
Inorganic phosphate is added to ADP+Pi to form ATP.
Energy is released when ATP is hydrolysed to ADP
Structure of a Chloroplast
- A double membrane called chloroplast envelope
- Thylakoid membranes - Stack to form grana and have a large surface area.
- Lamellae - Joins the grana together
- Photosynthetic pigments - Absorb light and attach to proteins to form photosystems
- Stroma - Contains enzymes and sugars for L.I.R
- Starch grains - store carbohydrates
- Ribosomes - Protein synthesis
Absorption of light
White light is a mix of different colours. Each colour has a different wavelength
- Blue: 450nm
- Red: 650nm
Chromatography Practical
1) Cut fresh leaf tissue and grind with sand
2) Put the sample in a test tube with propanone and shake
3) Add distilled water and shake
4) Add petroleum ether so solvents separate
5) Draw a pencil line on chromatography paper and allow the solvent to travel up the paper
6) The pigment will be left behind
The light-dependent Reaction
- This occurs in the grana inside the chloroplast
- This uses light to form ATP, NADPH
Non-cyclic phosphorylation
1) Light absorbed in PSII, electrons excite and move to higher energy level. These move down the E.T.C to PSI
2) Photolysis of water - Produces H*, E- and O2. Electrons then replace those in PSII
3) The electrons lose energy moving down the chain. Protons transporter to thylakoid creating a proton gradient. Protons move into the stroma via ATP synthase, Energy synthesises ATP
4) Light absorbed at PSI excites electrons to a high level, Electrons are transferred to NADP to form NADPH
Cyclic phosphorylation
This only produces small amounts of ATP
1) Electrons move to a high level
2) cycle back to PSI by moving down a small section of the E.T.C to produce small amounts of ATP
Light Independent Reaction
This occurs in the stroma of the chloroplast
The Calvin Cycle
1) Co2 combines with RuBP, this is catalysed by RUBISCO enzyme
2) 2 x Glycerate 3 phosphate (GP) are formed
3) ATP and NADP reduce GP to TP or GALP
4) Some GALP is used to make other organic compounds
4) The rest is regenerated to form RuBP again
