B-3.1: Summarize photosynthesis & interpret the formula

1. PHOTOSYNTHESIS 1 B-3.1: Summarize photosynthesis & interpret the formula

2. Essential Question: • What is the role of ATP in cellular activity? • SC B- 3.3:recognize the overall structure of ATP, namely, adenine, the sugar ribose, & three phosphate groups – and summarize its function(including ATP-ADP cycle Chapter 8 Section 1

3. Photosynthesis

4. autotrophs heterotrophs • Organisms that can make their own food (energy source) • plants • some bacteria • algae • Organisms that cannot make their own food; they have to consume food (energy source) • Animals • have to eat other organisms • Fungi • decomposers

5. Autotrophs Heterotrophs

6. ATP Adenosine Triphosphate is the principle chemical compound cells use to store and release energy Draw & label figure 8-3 on page 203 onto top ½ 0f page 53 of notebook

7. ATP  ADP + P releasing energy in the 3rd phosphate bond. This is a reversible reaction: ADP + P ATP

9. PhotosynthesiS OVERVIEWChapter 8-2 • EQ: How would you describe the relationship between chlorophyll and the color of plants?

10. Photosynthesis uses the energy in sunlight and carbon dioxide from the air to make glucose and releases oxygen into the air.

11. Draw, color, label figure 8-4 from page 206 on page 55 of your notebook

12. Pigments are also a necessary part of photosynthesis. Pigment: any light absorbing molecule Chlorophyll: principle pigment of plants; absorbs light energy

13. EQ: What happens in the light reactions of photosynthesis? Photosynthesis reactionschapter 8-3

14. Inside a Chloroplast: thylakoids: saclike membrane folds; appear like coins granum: stack of thylakoids stroma: space between granum and inner membrane

15. PHOTOSYSTEMS clusters of pigments in thylakoid membrane that capture energy from light Photosystem I & II

16. Light reactions • Use energy from light to excite electrons. Electrons absorb energy from light and go from their ground state to their excited state. These excited electrons then jump out of that atom & move through a series of molecules called the electron transport chain Notice this is happening in the thylakoid membrane

17. Photosynthesis begins when photons of light are absorbed by pigments in Photosystem II Ground state electron  excited electrons enter electron transport chain The electrons that left must be replaced: Enzymes breakdown 2 water  4H+ + O2 + 4 electrons Light reactions: Step 1

18. The excited electrons move thru the electron transport chain to Photosystem I Their energy is used to move H+ from the stroma to inner thylakoid space Light reactions: step 2

19. Light Reactions: Step 3 ( in Photosystem I now) • One of the electron carrier molecules is NADP+ • NADP+ carries 2 excited electrons with a H+ • In the process NADP+  NADPH thus converting some of the light energy into chemical energy • NADPH carries excited electrons to other molecules

20. Over time the inside of the thylakoid membrane fills with H+ making the outside of the membrane relatively negative compared to the inside (creating a difference in charge across the membrane) The difference in charges provides energy to make ATP Light reactions: step 4

21. The thylakoid membrane is impermeable to H+ Membrane protein called ATP synthase allows H+ to pass through membrane As H+ is passing through ATP synthase changes shape & in the process binds ADP + P  ATP Light reactions: step 5

22. Overview of light reactions • Things required • Light • Water • NADP+ • ADP + P • Things produced • Oxygen • NADPH • ATP

23. Harvesting Light Photosynthetic Electron Transport and ATP Synthesis Light reactions animations

24. How would you compare the role of Photosystem II and Photosystem I Time for thought

25. Light-Independent Reactions • aka: • Thermochemical cycle • Calvin Cycle

26. LIGHT-INDEPENDENTreactions: Part 1 • 6 carbon dioxide molecules enter chloroplast from atmosphere • Each combines with a 5-carbon sugar which then splits  (12) 3-carbon molecules

27. LIGHT-INDEPENDENTREACTIONS: Part 2 • Energy source for Dark reactions is the ATP made in light reactions • H added to carbon molecules is from NADPH made in light reactions

28. LIGHT-INDEPENDENTreactions: part 3 • 2 of the (12) 3-carbon molecules leave the cycle & are used by the plant to make compounds needed by the plant for metabolism and growth

29. LIGHT-INDEPENDENT reactions: part 4 • (10) C-C-C + 6 ATP  (6) C-C-C-C-C + 6 ADP • The remaining (10) 3-carbon molecules are converted back into 5-carbon sugars in a series of reactions powered by 6 ATP • These are used in the next turn of the cycle

30. LIGHT-INDEPENDENT reactions overview • Things required: • 6 CO2 • 18 ATP • 12 NADPH • Things produced: • 1 glucose (6-carbon) • 18 ADP • 12 NADP+

31. Photosynthesis equation

32. Factors affecting photosynthesis • availability of water • too much • too little • temperature • Photosynthesis enzymes work best 0 ◦C – 35 ◦C

33. Factors affecting rate of photosynthesis-2 3. light intensity as it increases rate of photosynthesis increases but only to a certain point, then it levels off

34. rainforests • About 2 ½ acres of Amazon rainforest absorbs 1 ton of CO2 per year • 20% of world’s O2 produced in Amazon