Photosynthesis. Chapter 6 . What is it?. Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar. Plants need only light energy, CO 2 , and H 2 O to make sugar.
Photosynthesis takes place primarily in plant leaves, and little to none occurs in stems.
Then at an individual plant cell. The chloroplast is inside the cell.
Look at the part of a chloroplast
The thylakoids contain pigments called chlorophylls. Chlorophyll a absorbs more red light than blue and is directly involved in the light reaction. Chlorophyll b assists.
After the pigments capture the light energy, how is this converted to chemical energy to make sugar?
2.The electrons are excited!
3. The electrons then go to a “primary electron acceptor”(PEA).
4. Then the electron goes through the ETC (electron transport chain)
5. But note: there are enzymes inside of the thylakoid which causes H20 to split under Photosystem II (keeping H+) releasing O2
See next picture
6. Within the ETC the electrons lose their excitement and are used to help split H2O molecules.
The Calvin Cycle (where the sugar is made)
5. 3-PGA gets converted to another three carbon molecule,G3P (glyceraldehydes 3 phosphate) ATP & H+ help to do this.
6. One G3P goes out to make carbohydrates
7. The remaining G3P the rest are used to convert back to RuBP to start the cycle over.