1. March 14, 2011 Agenda: Photosynthesis Lesson Photosynthesis Worksheet Review: Respiration Exam Lab Activity 24

2. Do Now: Pass forward light-reaction drawings
2) Describe what happens when chlorophyll absorbs light energy
Electrons become excited, and are passed down the electron transport chain on the thylakoid
membrane
Energy is absorbed by the electron, exciting it. Electron will be passed down the ETC and enzymes in membranes of the chloroplasts will release energy used to make ATP

3. If there is no CO2, very little oxygen was produced
Experimental set up
Test tube #1: Test Tube #2:
(Experimental) (Control)
Light Light
Chloroplasts Chloroplasts
H2O H2O
No CO2 CO2
If there is no CO2, very little oxygen was produced
How could we test our solution to ensure that there is no carbon dioxide present?
Set up experiment two times,s once with no carbon dioxide and no oxygen
If there is no carbon dioxide, very little oxygen is released. What is our problem?

4. AIM: Why is carbon dioxide necessary for photosynthesis?
Why do we need carbon dioxide to make oxygen during photosynthesis?

5. Review: Photosynthesis
CO2 + H2O (light energy)  C6H12O6 + O2

6. H2O  2 H2 + O2 This reaction is very endergonic
Hydrolysis: splitting of water
Water is being OXIDIZED
Splitting of water. This can be achieved using a Hoffman’s apparatus
Water is losing its hydrogen

7. If water is being oxidized, what else must happen?
Hydrogen acceptors

8. Water is oxidized, NADP is reduced

9. On a sunny day, the light dependent reactions will occur rapidly
On a sunny day, the light dependent reactions will occur rapidly. NADP will be reduced to NADPH. There is a limited amount of NADP in the thylakoid of the plant. …What’s the problem?

10. NADPH needs to be recycled to NADP for photosynthesis to continue to occur.
NADPH will lose its hydrogen;
CO2 will act as a hydrogen acceptor

11. Dark Reactions, Light-Independent Reactions, Calvin Cycle: NADPH and CO2 will be used to make glucose.

12. Light Reactions: Summary

13. Do Now: Take out homework

14. Dark Reactions
Synthesis of glucose from NADPH2 and CO2 using ATP energy
Takes place in the stroma of the cell

15. Dark Reactions Calvin was interested in studying the process
Of the “Dark Reactions”

16. Calvin traced carbon using a radioactive isotope (C14)
Chlorella- algae

17. Do Now: Why are the following necessary for photosynthesis?
Water: donates H+’s to form a hydrogen gradient and electrons through the ETC
CO2: combines with hydrogen from NADP to produce glucose
Light- excites electrons to pass through ETC
Water donates hydrogens to build to a hydrogen gradient
Donates electrons to the electron transport chain
Light- provides the energy to excite electons in photosystem II
CO2- accepts hydrogens from NADPH to recycle it to NADP

18. Review Calvin’s Experiment
Whoops! Not THAT Calvin….

19. Calvin’s Problem: How can carbon dioxide form glucose during photosynthesis?

20. Calvin’s Experiment
1) Calvin exposes the Chlorella (algae) to radioactive C 14 in C 14 O2 2) Allows photosynthesis to occur in lollipop apparatus 3) “Freezes” the reaction using ethanol alcohol a) release chlorophyll b) denature the enzymes involved in photosynthesis 4) Separates out radioactive carbon using CHROMATOGRAPHY

21. Chromatography- technique of separating different pigments based on chemical properties

22. 5. Observes radioactive compounds using “radioautography”
Technique that allows radioactive carbon to become visible.
By freezing photosynthesis at different times, Calvin was able to trace how carbon dioxide was converted to sugar.
This is is Calvin’s experimental procedure to determine the steps by which CO2 is converted into glucose. Now that we know how he set up his experiment, what question can we ask?
Elicit AIM:

23. AIM: What did Calvin discover?

24. Results of Calvin’s Experiment
ON BOARD: have students interpret the results of the experiment.
Begin with carbon dioxide, what’s our first compound to appear? (3 carbon PGA). What’s our second compound to appear? 3 carbon with 2 phosphates attached
Where might those phosphates have come from?
ATP
Then we have a 3 carbon sugar (PGAL)- we’ve seen this sugar before during a different process.
Cellular respiration (show cellular respiration slide
5 carbon sugar ribulose bisphosphate
And then a 6-carbon sugar- glucose
Calvin had hypothesized that CO2s combine to make glucose
If a CO2 combines with another CO2, then how many carbons would we have?
TWO
Do we see a two carbon compound in his results? No
So there must be a different pathway from Carbon Dioxide to glucose. Let’s take a look at what happens.

25. Glycolysis

26. Calvin Cycle: A
STEP A: Six carbon dioxide molecules enter the cycle from the atmosphere. The carbon dioxide molecules combine with six 5-carbon molecules. They rearrange to form 3 carbon molecules.
Look at our results, what is the first molecule to appear afte CO2?
PGA
How many carbons? 3
SO we form a 3 carbon compound

27. Step B: Energy investment stage
The 12 3 carbon molecules are then converted into higher energy forms. The energy for this conversion comes from ATP and NADPH
Where does the ATP and NADPH come from?
Where does the ATP and NADPH come from?
Light-dependnet reactions

28. STEP C: Two of the twelve 3-carbon molecules rearrange into two similar 3 carbon molecules (PGAL)
How many carbons are left? 30
How many 3 carbon molecules? 10
6 More ATP are used to make ribulose.
Why do we need to make ribulose?
So the cycle can continue again

29. Sheesh! That’s a lot of biochem..
Let’s summarize:
How many CO2 are needed to synthesize 1 glucose?
How many ATP are needed to synthesize 1 glucose?
How many NADPH are needed to synthesize 1 glucose?

30. Calvin Cycle
Energy input
Plants use energy that ATP and NADPH

31. Do Now: Take out homework Calvin Cycle Review How many: CO2 = 6
ATP= 18 ATP
NADPH= 12 NADPH

32. AIM: Why did the plant die?
I was so excited that I got this new plant. Look at my plant.
AIM: Why did Ms. Simon’s plant die?

33. Hypothesis: If the plant dies, then Photosynthesis is not occurring

34. Materials: Benedict’s Solution and Lugol’s Solution
Indicators for glucose and starch
Work together: What could I do?

35. Factors that may affect photosynthesis:
Sunlight
Water
CO2
Nutrients in the soil
Temperature
Light
Temperature
CO2
Water

36. Plants can still produce glucose for a short time in the dark…. Why?
However, Plants need NADPH and ATP from the Light-
Dependent reactions
to continue photosynthesis
Plants can still undergo the Calvin Cycle or light dependent reaction

37. Rainforest Desert
Large, broad leaves Small, needlike leaves Cuticle covering

38. How can temperature affect photosynthesis?
Enzymes in
Photosynthesis
work best between
0 and 35 degrees
Celsius, after 35
Celsius, enzymes
denature

39. How will carbon dioxide affect photosynthesis?
Carbon Dioxide is necessary during the Calvin Cycle to produce glucose

40. How will water affect photosynthesis?

41. How will water be transported to the top of trees?

42. Root Pressure
Concentration of nutrients and sugar is higher inside the roots than
outside the plant…
Water will move via
Osmosis into the
roots

43. Cohesion-Adhesion Cohesion: water Molecules attract to One another
Adhesion: water
Attracts to other sub-
Stances
Cohesion and Adhesion lead to capillary action- tendency for water to rise in a thin tube

44. Transpirational Pull- water moves into the leaves via osmosis
loss of water through
the leaves
Root pressure, capillary action, and transpirational pull contribute to the movement of water within a plant

45. Wilting
Too little water decreases TURGOR pressure in a plant, causing it to wilt

46. Summary: What may be wrong with Ms. Simon’s plant?