photosynthesis song photosynthesis song 2

photosynthesis video Light Reaction Video

Autotrophs V. Hetertrophs Heterotrophs Organisms that CANNOT make their own food Eat others Animals

Autotrophs Organisms that make their own food Plants, algae, some bacteria Photosynthesis Chemosynthesis

Photosynthesis Converting light energy from the sun into chemical energy, which they then store primarily as glucose Need: Carbon Dioxide Water Light

Biochemical pathways A series of chemical reactions in which the product from the first reaction is needed and consumed in the next EX: Cellular Respiration (Auto/Heterotrophs) Photosynthesis (Autotrophs)

Light Travels in waves of energy White: combo of visible spectrum Visible Spectrum: ROY G. BIV ( R=longest…V=shortest) Measured in wavelengths Pigments absorb colors Reflect what we see Pigment: Molecules that absorb light

Why are plants green? It’s the only color that doesn’t get absorbed by the pigments so our eyes see it.

Chloroplast

Thylakoid Membrane: discs that contain pigment; all light capture occurs here Grana: stacks of thylakoids Stroma: gel like substance that surrounds

Pigments Chlorophyll a: only one involved in PS I and PS II; main pigment Accessory pigments: aid in light capture; absorb different wavelengths; more efficient; fall (amt. sun) 1. chlorophyll b 2. carotenoids ( yellow, orange, brown) 3. xanthophylls (yellow green) 4. Anthocyanin (red) Other pigments show up in the fruits/flowers

Photosynthesis What is it??? Occurs in 2 reactions: Light & Dark

Light Reaction Needed to fuel Dark Reaction (biochemical pathway) 2 parts Light Capture 2. Electron Transport Chain

Light Capture (Sunlight) 1st step in photosynthesis Accesssory pigments and chlorophyll a capture light ( in the form of bonds) Light E is the fuel!!!! Chloroplast(thylakoid membrane)

Electron Transport Chain 2 parts 1. Photosystem I 2. Photosystem II Electron Transport Chain song Occurs b/c water splits and ELECTRONS are FREE!

Steps of ETC (Water) Photosystem I Chlorophyll a absorbs light E (photon)…electron become excited Electrons are boosted to next E level leave chlorophyll a (oxidation) PEA (primary electron acceptor) accepts electron (reduction) PEA donates e to stroma Electron combine with NADP & protons Result: NADPH

Steps ETC (p.2) Photosystem II Chlorophyll a continues to capture light & replace lost electrons…allows reaction to continue (fuels it) Water splits===free electrons and Oxygen Chemiosmosis: synthesis of ATP; electrons combine with ADP

Result of Light Reactions 2 ATP 1 NADPH light reactionl These will be used to fuel Dark Reactions !!!!! (biochemical pathway)

The Dark Reaction (CO2…) AKA Calvin Cycle Occurs in the Stroma CO2 enters through the stoma on the leaf) Remember: Hydrogen protons build up in thylakoid membrane from water splitting…pumped into stroma (active transport)..this creates a concentration gradient (draw picture) Goal of photosynthesis: capture Carbon atoms from carbon dioxide and use them to make sugar (glucose) equation:

Carbon fixation Incorporation of carbon into organic molecules Occurs during Calvin Cycle Carbon from carbon dioxide

Calvin Cycle Powered by ATP and NADPH (from light rxn) Goal= glucose from carbon Carbon dioxide diffuses into stroma from cytosol

Steps: 1. Carbon dioxide diffuses into the stroma from the cytosol 2. PGAL, a 3 carbon molecule, is converted into PGAL, another 3 Carbon molecule. ADP, NADP, and phosphate are also produced and can be used in the light reactions. 3. RuBP made

For every turn of the Calvin Cycle the following is produced: 1 ATP 1 PGAL (3 turns) USES: 2ATP 2NADPH

Equation

Dark reaction Photosynthesis overview

Use what you’ve learned about photosynthesis to explain the humor in this cartoon.

Rate of Photosynthesis Light Intensity: increase l.i. increase rate initially then levels off Carbon Dioxide: increase rate initially Temperature: increase accelerates chemical reactions therefore increasing rate. Temperature: too high stops photosynthesis b/c stomata close not allowing carbon dioxide in or water out.