Photosynthesis

Photosynthesis

1. Basics

   • Photosynthesis
   • Autotroph
   • Hetrotroph

2. Chloroplasts

   • Structure
   • Adaptations to role
   • Photosynthetic pigments
     • Primary pigments
       • Chlorophyll a
     • Accessory pigment
       • Chlorophyll b, beta carotene
     • Advantages of having more
       • Able to absorb more wavelengths of light

3. Light dependant stage

   • Cyclic
     • Electrons return to PSI if NADPh is not produced and the energy released produces ATP. This ATP is either used in light dependant photosynthesis or is used in guard cells to bring K+ into the cell, lowering the water potential, causing them to swell and open the stomata and allow more CO2 in or O2 out
     • Products
       • ATP
   • Non-cyclic
     • Products
       • 1x ATP, 2 NADPh
     • PSII, P680
       • Light strikes PSII and a pair of electrons part of a Mg are excited and they leave the molecule from part of the primary pigment reaction centre
       • Electrons replaced by those from photolysed water 
       • 2e-
         • These electrons move down a electron transport chain, the energy released synthesises an ATP molecule
         • PSI, P700
           • Light hits here and more electrons are lost
           • Electrons are replaced by the ones from PSII
           • Ferredoxin, 2e-
             • NADP reductase
               • The enzyme that produces NADP All the products so far combine to form NADPh
               • <-- 2NADP
               • NAPDH -->
                 • A coenzyme picks up the protons. This is then used in the light independent stage
       • 2H+ + 1/2 O2 <---
         • <-- 2H+
       • H2O --->
         • Photolysis occurs and water is broken down by light making 2H+ and half an O, so if this happens twice an O2 molecule is given off
   • Photophosphorylation
     • Making ATP in the presence of light
   • Electron carriers
     • Molecules that transfer electrons
   • Electron acceptors
     • Chemicals that accept electrons from another compound, theyre reduced while acting as a oxidising agent, e.g. DCPIP

4. Light independent stage

   • Rubisco
     • 2GP
       • 2TP
         • RUBP
           • Rubisco
             • CO2 ->
         • ATP -> ADP
         • Products
           • Cellulose and starch (poly saccharides)&nbsp; Glucose, fructose, sucrose, glycerol (can be combined with fatty acids to form lipids)&nbsp;
       • NADPh -> NADP
       • ATP -> ADP + Pi
       • Products
         • Amino acids, Fatty acids

5. Limitations

   • Light intensity
   • CO2
   • Water
   • Temperature

6. Investigating rate

   • Ways to improve