1. Chapter 14 Energy Generation in Mitochondria and Chloroplasts

2. Protons In H 2 O H + can move along the H- bonds in H 2 O Dissociating from one molecule to associate with the next one

3. Transfer of H + and e - The transfer of an e - sets up a negative charge which is rapidly neutralized by adding a H +, the molecule is reduced Reverse is true when things are oxidized

4. e - Transport Chain

5. Redox Potential Redox = oxidation-reduction reactions Depends on the affinity for electrons of the molecules involved in each reaction Redox pairs – two molecules such as NADH and NAD + - NADH is a strong electron donor (reducing agent) while NAD + is a weak electron acceptor (oxidizing agent) Redox Potential – a measure of the tendency of a given system to donate or accept electrons

6. Versatile Electron Carriers The respiratory complexes are made up of a metal ion bound to a protein molecule The metal ion is responsible for the movement of the e -, skipping from one ion to another Ubiquinone, a hydrophobic molecule, that can move electrons without being bound to a protein

7. Quinone Electron Carriers Can carry either 1 or 2 e - and picks up 1 H + for each e -

8. Other e - Carriers Dehydrogenation complex –Flavin group –Iron-sulfur centers – carry 1 e - at a time Cytochrome b-c 1 and cytochrome oxidase complexes –Proteins that contain a heme group that can accept an e - –Cytochromes are colored due to the Fe

9. Chloroplasts and Photosynthesis Photosynthesis is process using the energy in sunlight and CO 2 to create the organic materials required of present day cells The chloroplast is the special organelle in plants responsible for photosynthesis

10. Chloroplasts Similar to mitochondria Uses a proton pump to create ATP Stroma instead of matrix Has own RNA, DNA and ribosomes Difference is that the e - transport chain is in the thylakoid membrane – 3 rd membrane that makes up the thylakoids, a sac-like structure, so have a thylakoid space Granum – stack of thylakoids

11. Chloroplasts vs Mitochondria

12. Light and Dark Reactions Light or photosynthetic e - transfer reactions –Sunlight energizes e - in chlorophyll which then moves down the e - transport chain in the thylakoid membrane –e - gotten from H 2 O to make O 2 –Electrochemical gradient is made in the stroma across the thylakoid membrane making ATP –Generate NADPH from NADP + Dark or carbon-fixation reactions –ATP and NADPH produced in light reaction used as energy and reducing power to take CO 2 and convert it to a carbohydrate – glucose

13. Photosynthesis Reactions

14. Chlorophyll Sunlight is composed of many different wavelengths ranging from violet to red Chlorophyll is green because it absorbs all the wavelengths but green The e - in chlorophyll gain a higher energy level when a wavelength is absorbed and then bounce around the ring – porphyrin (blue)

15. Photosystem Chlorophylls are in a multiprotein complex called a photosystem Antenna is many molecules of chlorophyll that capture the sunlight’s energy that ultimately goes to the reaction center

16. Set of proteins in the thylakoid membrane Special chlorophyll molecule that is an irreversible trap for an excited e - Transfers the e - to a more stable environment Reaction Center

17. ATP and NADPH The light reaction makes the ATP and NADPH to synthesize the sugar ATP made with the first photon of light absorbed and NADPH is made from the second photon of light

18. Summary of Light Reactions Electron from chlorophyll in photosystem II is donated to NADPH The replacement electron comes from the splitting of water When 4 electrons are removed (4 photons hit chlorophyll) O 2 is released

19. Carbon Fixation or Dark Reaction

20. Carbon-Fixation or Calvin Cycle CO 2 joins with a ribulose 1,5-bisphosphate (5 C) by a carboxylase called rubisco –Rubisco is slow compared to other enzymes so therefore there is a large amount in the cell to compensate for this 1 molecule of glyceraldehyde 3-phosphate (net product ) is generated and goes to make the sugar A large amount of energy goes to regenerating the ribulose 1,5-bisphosphate 3 ATP and 2 NADPH required for each CO 2 molecule converted to carbohydrate

21. Glyceraldehyde 3-phosphate Converted into glucose Can be shuttled into the glycolytic pathway in the mitochondria of plants to become pyruvate and eventually ATP Excess is converted into starch in the stroma which can be used at night as an energy source