Photosynthesis, Chapter 6-1 page Capturing light energy and storing it within organic compounds +

Energy Processes In photosynthesis, the products of one reaction gets consumed in the next reaction This series of reactions = biochemical pathway Equation for photosynthesis Carbon Dioxide + Water -> Oxygen + Biomolecules

Algae changes the world Early Earth had an atmosphere with no oxygen in it The only living things emitted oxygen as a waste product This changed the atmosphere Ironically, those species died

We can’t let the plants get away with it The opposite of photosynthesis is cellular respiration Equation for cellular respiration Biomolecules + Oxygen -> Carbon Dioxide + Water

chloroplasts Chloroplasts absorb light Flattened discs inside are called thylakoids Stacks of thylakoids = granum Fluid that all this is sitting in = stroma

Lights, Chlorophyll, Action We see energy of different wavelengths as different kinds of color Pigments are compounds that absorb light If a color is absorbed it doesn’t reflect The color black absorbs most of the colors

Pigments Chlorophyll comes in two kinds a and b a absorbs more red light than b b only helps a so its an accessory pigment Green light is reflected from chlorophylls so plants appear green

Other pigments Carotenoids absorb other colors and reflect earth tones You don’t normally see it until chlorophyll dies When does that happen during the year?

Electron transport All going on in a thylakoid 1.Chlorophyll a molecules in Photosystem II get excited from light 2.e - are passed to the primary e - acceptor 3.e - go down an electron transport chain 4.These e - come into Photosystem I because Photosystem I just gave away a pair 5.Another electron transport chain combines NADP + with a Hydrogen atom to get NADPH

Chemiosmosis Part of the light reactions is the creation of ATP The energy for this comes from the concentration gradient of Hydrogen protons (H + ) There are more H + inside the cell than outside ATP Synthase lets H + out and harnesses energy from that to make ATP

Objectives, Now can you… Explain how the structure of a chloroplast relates to its function? Describe the role of chlorophylls and other pigments in photosynthesis? Summarize the main events of electron transport? Describe what happens to water in photosynthesis? Explain how ATP is synthesized during light reactions?