1. Do Now
What does a chloroplast look like? How do plants obtain energy? What is the formula for glucose? How do autotrophs obtain energy? How do heterotrophs obtain energy?

2. Photosynthesis: Capturing and Converting Energy
Chapter 6
Photosynthesis: Capturing and Converting Energy

3. Energy – the ability to do work

4. Photosynthesis
Plants use the energy of sunlight to produce carbohydrates
Energy is now in the chemical bonds

5. Jan Van Helmont Where does a tree’s increased mass come from?
Seedling – 5 years – soil same mass – tree gained 75 kg
Conclusion  water “hydrate”

6. Priestly Candle and a jar  candle goes out – no oxygen
Candle + jar + plant  candle does not go out

7. Ingenhousz
Oxygen produced in light

8. Equation for Photosynthesis

11. Requirements for Photosynthesis

12. 1. Sunlight Autotrophs – can use sunlight to make food
Ex. Plants obtain energy
Heterotrophs – obtain energy by eating other organisms
Ex. Animals
All organisms on earth depend on the sun for energy

13. Sunlight is “white” light
Many wavelengths of light
ROYGBIV – visible spectrum

14. 2. Pigments Colored substances that absorb or reflect light
Photosynthesis begins when light is absorbed by pigments
Chlorophyll – principle pigment of green plants
Absorbs red and blue and reflects green light

15. Chromatography
Paper chromatography is a way to separate chemical components of a solution.
How it Works
A drop of solution is placed at the bottom of a paper.
The paper is put in a solvent (tip only).
The solvent rises through the paper.
As it rises it carries the solution with it.
The parts of the solution move at different speeds depending on their mass. Lighter molecules move faster.

16. 3. Energy Storing Compounds
Like solar cells
Electrons are raised to higher energy levels – then trapped in bonds
Two ways that energy from the sun is trapped in chemical bonds

17. High energy e- are passed to an electron carrier
(NADP +)  NADPH
Electron carrier – a molecule that can accept a pair of high energy electrons and later transfer them with most of their energy to another compound
Conversion of NADP+ to NADPH – one way that energy from the sun can be trapped in a chemical form

18. Second way light energy is trapped  ATP (Adenosine Triphosphate) – 3 phosphates
Fig 6-6
Green plants produce ATP in photosynthesis
ATP energy storage compound used by every cell

19. Producing ATP AMP (mono) – one phosphate AMP + P  ADP (two – di)
ADP + P  ATP
Energy is stored in the P bonds
Energy is released when P bonds are broken

22. Section 9.1 Summary – pages 221-224
Forming and Breaking Down ATP P P P
Adenosine
Adenosine triphosphate (ATP) P P
Adenosine diphosphate (ADP) P P
Adenosine
Section 9.1 Summary – pages

23. 6-2 Photosynthesis: The Light and Dark Reactions
Light Reaction – energy of sunlight captured to make energy storing compounds
ATP and NADPH
Short term energy storage

24. Section 9.2 Summary – pages 225-230
Sun
Light-Dependent Reactions
Light energy transfers to chlorophyll.
At each step along the transport chain, the electrons lose energy.
Chlorophyll passes energy down through the electron transport chain.
Energized electrons provide energy that
splits
H2O
bonds P
to ADP
forming ATP H+
oxygen
released
NADP+
NADPH
for the use in light-independent reactions
Section 9.2 Summary – pages

25. Dark Reaction – energy from ATP and NADPH to make glucose (100 x the energy)
Long term energy storage

26. The Light Reactions

27. Chloroplast Parts of a chloroplast Stroma – “cytoplasm”
Grana – pancake
Thylakoid – stacks of pancakes (grana)
Thylakoid = photosynthetic membrane

29. 4 Parts of the Light Reaction
Light absorption
Electron transport
Oxygen production
ATP formation

30. Photosystems
Clusters of pigment molecules that capture energy from the sun
Two in plants – Photosystems I and II

31. Photosynthesis – plants - autotrophs
Occurs in the chloroplast
Absorbs light
Light reaction occurs in the thylakoid (photosynthetic environment) – needs sun to occur

32. Light Absorption Photosystem I & II – absorb sunlight
Pigment molecules pass the energy to other pigment molecules
Reach a special pair of chlorophyll molecules in the reaction center
High energy electrons released and passed to many electron carriers

33. Electron Transport Electron transport – electron transport chain
e- passed from one carrier to another (bucket brigade)
Passed to electron carrier NADP+
NADPH

34. Electron Transport Chain

35. NADPH – restoring electrons
Water is split (photolysis)
2 H2O  4 H+ + O2 + 4 e-
Oxygen is released
4 e- go to the chloroplast
4 H+ are used to make ATP

37. ATP Formation 4 H+ released inside the membrane H+ build up
Inside positive – outside is negative (charge difference is a source of energy)
Enzymes use this energy to
attach P to ADP  ATP

39. The Dark Reaction or Calvin Cycle

40. The Dark Reaction or Calvin Cycle
Does not need sunlight to happen
Often happens with sunlight
Uses products of the light reaction (ATP + NADPH)
This series of reactions is particularly critical to living things
Carbon dioxide is used to build complex organic molecules  glucose

41. Dark Reaction or Calvin Cycle
Occurs in the stroma
5 C sugar (RuBP) + CO2
This reaction is slow and is catalyzed by rubisco
Next two 3 C sugars are produced (PGA)
ATP and NADPH from the light reaction are used to convert PGA eventually into PGAL (3 C) – products P + ADP and NADP+
PGAL can use some ATP and become RuBP (5 C)
After several turns of the cycle 2 PGAL can leave and form glucose

44. 6-3 Glycolysis and Respiration

45. Enables organisms to release energy in glucose
Breaks down food molecules
C6H12O6 + 6O2  6CO2 + 6H2O + energy (ATP)
1 g of glucose  3811 calories
1 cal = amount of heat energy to raise
1 g of water 1 OC

46. Glycolysis occurs in the cytoplasm
Changes a molecule of glucose into many different molecules step by step

47. Glucose (6 C)
2 ATP are used to make 2-3-C PGAL
PGAL is converted into pyruvic acid and 4 ATP and 2 NADH are produced
Pyruvic acid can enter aerobic or anaerobic respiration based on whether there is oxygen available or not

48. Presence of Oxygen – Cellular Respiration
Aerobic oxygen needed
Takes place in the mitochondria
Krebs cycle (Citric Acid Cycle)
Starts with Pyruvic acid
Carbon dioxide is removed
Acetyl CoA is produced
Citric acid is then produced
9 reactions
9 intermediate
citric acid is produced and the cycle begins again
Carbon dioxide is released
Make FADH2 and NADH

49. FADH2 and NADH go to the inner membrane of the mitochondria
Electrons passed to enzymes
Electron transport chain
At the end – enzyme combines
H+ + O2  H2O
Therefore Oxygen is the final electron acceptor
Mitochondrial membrane is charged (H+ ions pumped to one side)
Provides energy to convert ADP  ATP
36 ATP are produced

51. 6-4 Alcoholic Fermentation

52. Glycolysis – net 2 ATP
NAD+  NADH
If you remove an electron from NADH glycolysis can continue

53. Fermentation – Anaerobic (no Oxygen)
NADH converted to NAD+ (acceptor molecule take the H)
Allows cells to carry out energy production in the absence of oxygen
1 glucose  2 ATP
Prokaryotes use many different acceptors
Eukaryotes use two different acceptors
1. Lactic acid fermentation
2. Alcoholic fermentation

54. Alcoholic Fermentation
Occurs in yeast and a few other organisms
Pyruvic acid is broken down to produce 2-C alcohol and carbon dioxide
Pyruvic acid + NADH  alcohol + CO2 + NAD+
Brewers and bakers
Carbon dioxide produced causes bread to rise
Bubbles in beer
Yeast dies at 12% alcohol content

55. Lactic Acid Fermentation
Pyruvic acid created in glycolysis can be converted to lactic acid
The conversion regenerates NAD+
Pyruvic acid + NADH  lactic acid + NAD+
Lactic acid produced in muscles during rapid exercise when the body does not supply enough oxygen
Lactic acid – produced burning sensation in muscles

57. Section 9.3 Summary – pages 231-237
Comparing Photosynthesis and Cellular Respiration
Table 9.1 Comparison of Photosynthesis and Cellular Respiration
Photosynthesis
Cellular Respiration
Food synthesized
Food broken down
Energy from sun stored in glucose
Energy of glucose released
Carbon dioxide taken in
Carbon dioxide given off
Oxygen given off
Oxygen taken in
Produces sugars from PGAL
Produces CO2 and H2O
Requires light
Does not require light
Occurs only in presence of chlorophyll
Occurs in all living cells
Section 9.3 Summary – pages

59. The End