Photosynthesis Notes

Write the equation for photosynthesis.

                                             chlorophyll

6CO₂  + 6H₂O  +  sunlight                            C₆H₁₂O₆   +   6O₂

carbon     water        energy                              glucose            oxygen

dioxide

Photosynthesis – the process by which light energy is converted to chemical energy stored in organic molecules

Chloroplast – organelle that is the site of photsynthesis

Granna – stacks of membrane sacs that contain chlorophyll

Thylakoid – the membrane sacs that make up a granum

Frets – membranes that connect granna

Stroma – protein rich substance that surrounds the granna

Chlorophyll – pigment in the chloroplast that absorbs solar energy

                       Chlorophyll reflects the green wavelengths and absorbs energy from the

                        other color wavelengths.

Photosystem – light collecting units of the chloroplast made up of chlorophyll molecules

Two Parts of Photosynthesis

1. Light-dependent reactions – occur in the granna

                          Steps of the Light-dependent Reaction

1. Sunlight splits the water molecule in a process called photolysis ; oxygen,

hydrogen ions, and electrons are released

2. Photosystem II pigments absorb light.
3. Electrons absorb energy and are bounced to higher energy levels
4. Electrons of Photosystem II move to electron carriers that pass them down to their lower original energy
5. Electrons of Photosystem II are passed to Photosystem I by an electron transport chain in the thylakoid membrane to replace the electrons lost by Photosystem I
6. Electrons from Photosystem I are bounced out to higher energy levels by absorption of sunlight.
7. Electrons from Photosystem I are picked up by NADP
8. NADP also picks up hydrogen ions; NADP is a hydrogen acceptor and an electron acceptor.
9. When NADP picks up hydrogen ions it forms NADPH; NADPH is an energy source for the light independent reaction
10. Electrons from water replace those lost from Photosystem II
11. As hydrogen ions move through the thylakoid membrane they cause the phosphorylation of ADP into ATP using the enzyme ATP synthase; the ATP will be an energy source for the light independent reaction

2. Light Independent Reaction – occurs in the stroma

(Calvin Cycle, C₃ Cycle)