Chapter 5 Photosynthesis

1. Chapter 5 Photosynthesis

2. 5-1 NRG and Living Things • Where does the NRG we use come from. • Directly or indirectly from the sun • Plants get their NRG directly from the sun • How?

3. Plants use photosynthesis to convert light NRG into chemical NRG • Plants are autotrophs • Autotrophs convert light NRG or inorganic compounds to make organic compounds • Photoautotrophs use the sun • Chemoautotrophs use inorganic compounds

4. Heterotrophs must eat things to aquire NRG from organic compounds • Cellular Respiration is how most heterotrophs, and most autotrophs get their NRG from organic compounds • Similar to burning fuel (uses oxygen), to build ATP

5. Organisms get NRG from compounds by breaking chemical bonds • Some NRG gets released as heat when breaking chemical bonds • Most of the remaining NRG gets temporarily stored as ATP

6. ATP • ATP yields ADP + P + NRG • Made of a nitrogen base, ribose sugar, and three phosphate groups • How is the NRG released? • By breaking the chemical bond between phophate groups

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8. 5-2 Photosynthesis • Stage One and Two (Light RXNS) • Chloroplast contain pigments that absorb solar NRG • Primary pigment is called chlorophyll and absorbs blue, red light waves • Two types of chlorophyll a and b

9. Carotenoids are yellow and orange pigments • They absorb different wavelengths of light

10. Stage 1 • Pigments are located in chloroplast • Embedded in the membranes of thylakoids (disk shaped) • When light hits them, NRG is transferred to electrons • Makes them “excited”

11. Excited electrons jump from chlorophyll molecules to other molecules in the thylakoid • These electrons fuel the second stage of photosynthesis

12. Plants must replace these lost electrons • Water molecules get spilt by an enzyme • Electrons are taken from hydrogen atoms, leaving H+ • The oxygen is combined to form oxygen gas

13. Stage 2 • Electrons are used to produce new molecules that store chemcal NRG • Electrons are passed between molecules in the thylakoid membrane • Called the Electron Transport Chain

14. One type of e- chain contains a protein that acts like a membrane pump • The e- lose their NRG as they pass through the protein • This NRG is used to pump H+ into the thylakoid • This creates a concentration gradient inside the thylakoid

15. The H+ then diffuse out the thylakoid through special carrier proteins • These carrier proteins function as enzymes and ion channels • These proteins catalyze a reaction that adds a phosphate group to ADP to create ATP

16. ATP used to fuel stage 3

17. Another e- transport chain makes NADPH • NADPH is an electron carrier that provides NRG to make carbon-hydrogen bonds in stage 3 • NADP+ + Hydrogen ions=NADPH

18. Light RXNS Summary • Pigments in thylakoids capture solar NRG • Electrons become excited and move through the e- transport chain • Electrons are replaced by splitting water molecules • H+ accumulate in thylakoid, helping to create ATP and NADPH

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