Part 2: Photosynthesis overview, chloroplast structure & pigments Unit 4 Cell Energetics! Part 2: Photosynthesis overview, chloroplast structure & pigments

Learning Targets Identify the inputs and outputs and location of the light reactions (LDR) and Calvin Cycle (LIR). Describe the purpose of chlorophyll and accessory pigments. 7. Compare and contrast the structure and function of mitochondria and chloroplasts.

Chloroplast structure Be able to ID the following: Inner membrane* Outer membrane* Granum Thylakoid Stroma *supports the endosymbiotic theory

Endosymbiotic Theory? A larger cell (pre-eukaryote) engulfed a smaller prokaryote  the smaller one provided energy  instead of “eating” the small bacteria they became bffs Other evidence that supports this Chloroplasts & mitochondria have their OWN DNA!!! 

Chloroplasts… Found in mesophyll 1 mesophyll cell may have 30 chloroplasts! (remember the elodea?)

Photosynthesis Overview Light reactions (LDR) Depend on light Occur in Thylakoid Membrane Light Independent reactions (LIR) Does NOT need light Occurs in the Stroma

Location, location, location Learning check: Light Dependent Reaction occurs…where? Light Independent reaction occurs…where?

Photosynthesis background Pigments this is what absorbs the light energy from the sun it excites electrons making it unstable Photosystems (PS 1 & PS 2) Made of pigments & proteins

Pigments Chlorophyll Chlorophyll a  main pigment  blue-green Chlorophyll b  accessory pigment  yellow-green Other accessory pigments  absorb different wavelengths of light Carotenoids  yellow-orange Xanthophyll yellow Rhodophyll  red Fucoxanthin  brown Why are plants green? Why are plants changing color?

Photosystems Consist of There are 2 Pigments (chlorophyll b, carotenoids & xanthophyll) Proteins! There are 2 Photosystem 1 The last photosystem in the Light Dependent Reaction (LDR) Photosystem 2 The FIRST photosystem in the LDR Photosystem 2 comes first, but has the #2 after it because we discovered it second…

Photosystems Process: Photon (light energy) absorbed by pigments  excites e- in pigment e- jump to higher levels  eventually reaches the reaction center (chlorophyll a)  transfers energy to the reaction center  passed back down through an ETC in LDR

Learning Check Where does the Light Dependent Reaction occur? 2. Where does the Light Independent reaction occur? What factors could affect the process of photosynthesis? What do pigments do (purpose & function)? What happens in a photosystem? What is a photosystem? What is the relationship between PS1 & PS2 (similarities, order, help each other?)