1. Using Light to Make Food
PHOTOSYNTHESIS
Using Light to Make Food

2. It provides food for virtually all organisms
Photosynthesis is the most important chemical process on earth because:
It provides food for virtually all organisms
SWEET!!!!

3. BIG PICTURE: Photosynthesis
Light energy is used to make sugar and other food molecules from carbon dioxide and water

4. 6 H2O + 6 CO2 ----------> C6H12O6+ 6 O2
Chemical Reaction
sunlight
6 H2O + 6 CO > C6H12O6+ 6 O2
How does this equation compare to the cell respiration one?
Photosynthesis: An Overview of Photosynthesis (click)

5. Autotrophs“Self-feeders”
Make their own food
Also referred to as: Producers = produce the biosphere’s food supply

6. Photosynthetic Plants
Forests (land)
Kelp (ocean)
Diatoms
(microscopic)

7. Leaf Structure

8. 1. Stoma (sing.) in leaf lower epidermis
Is the opening
carbon dioxide, oxygen. And water in/out
Stomata (pl.)

9. Leaf CS 2. Upper Epidermis 4. Mesophyll-cells containing chloroplasts
3. Lower epidermis
Covers and protects
see stoma –in lower epidermis only

10. 4. Mesophyll
= Palisade Layer + Spongy Layer

11. Waxy, waterproof coating (to retain H2O)
5. Cuticle
Waxy, waterproof coating (to retain H2O)

12. 6. Palisade Layer
cylindrical cells, vertically oriented, closely packed

13. O2 ,CO2, H20 vapor go in/out 7. Spongy Layer
cells are irregular in shape and loosely packed
O2 ,CO2, H20 vapor go in/out

14. 8. Guard Cells Control Stomata
Full guard cells (turgid) opens the stoma.
Flaccid (lost water) guard cells, the stoma closes.
ANIMATION: Stoma
What causes them to open? What goes into the stomata?

15. 9. Plant Vein: Xylem + Phloem
Xylem-(blue) carries water
Phloem (thicker cell wall)-(yellow) carries food

16. 10: Air Space Gas Flow Through Leaf

17. Guard Cells Animations
LabBench (guard cell animation)
Another animation of opening and closing of guard cells
(really nice)

18. Water Movement
LINK:

19. Draw the Elodea Cell 400X

20. Leaf CS (cross section)

21. Photosynthesis in Elodea Lab
See oxygen bubbles coming from the Elodea
What conditions are best?

22. Elodea Bubbles Movie
sLowlife Exhibit

23. 7.2

24. Chloroplast

25. Chloroplast Diagram Stroma = thick fluid between the thylakoids
thylakoids = disks within the chloroplasts
granum=stack of thylakoids (grana pl.)

26. What is the difference between grana and granum?

27. STROMA So what’s the difference between the stoma and the stroma?
STOMA = opening in lower epidermis
STROMA = area around thylakoid disks in the chloroplast

28. Chloroplast Diagram Inner Membrane Thylakoid space Intermembrane Space
Stromal lamella = connect grana
D. Outer Membrane
Thylakoid membrane
Inner Membrane
Thylakoid space
Intermembrane Space

29. Chloroplasts TEM Note the stacks of thylakoid disks = grana
Note area between = stroma

30. THYLAKOIDS

31. Photosynthesis

32. Summary IN

33. Summary OUT

34. Nice Little Photosynthesis Movies
VCAC: Cellular Processes: Photosynthesis: The Movie
VCAC: Cellular Processes: Photosystem II: The Movie

35. 7.5 Overview of Photosynthesis

36. What happens here? Assembles sugar molecules using CO2
Light Dependent Reaction (LDR)
Converts light energy to chemical energy + O2
Light Independent Reaction (LIR)
Assembles sugar molecules using CO2

37. Where does energy come from?
Light Dependent Reaction LDR
Uses light energy
Light Independent Reaction LIR
(Calvin Cycle)
uses ATP and NADPH (from LDR)

38. PSI and PSII
PSI and PSII animation
Another PSI and PSII animation

39. Where is it located in the cell?
LDR
occurs in thylakoid membranes of chloroplast’s grana
LIR (aka Calvin cycle)
occurs in stroma of chloroplast

40. Final Products of Each?
LDR
ATP and NADPH
Also O2
LIR
sugar

41. Carbon fixation = FIXATION = make in a usable form
NEW VOCAB. WORD
Carbon fixation =
incorporation of carbon into an organic molecule (useable)
EXAMPLE: CO2 into C6H12O6
FIXATION = make in a usable form

42. LIGHT
CHLOROPHYLL

43. Pigments in Plants Pigments are light-absorbing molecules
Different pigments absorb or reflect different colors

44. Wavelength Chlorophyll a wavelengths absorbed: blue-violet and red
Reflects: grass green
Wavelength

45. An accessory chlorophyll in plants
Chlorophyll b
Absorbs: blue and orange
Reflects: yellow-green
An accessory chlorophyll in plants

46. Other pigments in plants
Carotenoids-orange
Absorb: blue-green
Reflect: yellow-orange

47. FYI Why do leaves change color?
Chlorophyll breaks down and exposes the other colors that were there all along, but were masked by the green chlorophyll.
As fall comes there are shorter days of sunlight
Less photosynthesis means less food for plants.

48. “Absorption of Chlorophyll”
DO WORKSHEET
“Absorption of Chlorophyll”
Photosynthesis: The Action Spectrum for Photosynthesis (experiment link)

49. Chlorophyll a and Chlorophyll b

50. 7.7 Electromagnetic Photosynthesis: Electromagnetic Energy
(move the arrow)

51. #1 What are…
PHOTONS
Fixed quantity (packet) of energy

52. Distance between crests of two waves
Λ = symbol for wavelength

53. Light travels as waves and as photons
“Wave-particle theory”

54. PHOTONS
Smallest unit of light emitted when an electron jumps to a more excited state
named by Einstein
light

55. Shorter the wavelength...
The greater the energy

56. #2 When an e- in a pigment absorbs a photon...
Electron goes from “ground state” to “excited state”

57. Energy from the sun
ANIMATION: Atomic absorption diagram (how energy causes an electron to jump levels)

58. #3 Excited State is Very Unstable
As e- falls back to the ground state it might:
lose energy as heat
emit light
gives off a photon
IN A CHLOROPHYLL MOLECULE IT WILL …

59. PHOTOSYSTEM

60. Now for photosynthesis

61. #3 + #4 Chlorophyll passes its photon to:
A neighboring molecule called the primary electron acceptor

62. Reaction Center of Chlorophyll
Chlorophyll a is the only one that donates to the primary acceptor
CENTER

63. Pigments in a Photosystem (Light RXN)
reaction center
Figure 7.11 Page 122

64. “Light capturing Antenna”
Transfer light energy to the reaction center

66. #4 “Photosystem” = PS
Antenna molecules + reaction center + primary electron acceptor

67. Cyclic Electron Flow (Light RXN)
electron acceptor
Electron flow through transfer chain sets up conditions for ATP formation at other membrane sites.
electron transfer chain e– e–
ATP e–
Figure 7.12 Page 122

68. #5 TWO photosystems: PS I and PS II: absorbs λ (λ = wavelength) PS I -P 700 nm PS II -P 680 nm

69. Animations P700 and P680 Animation
Making ATP and NADPH (Light Dependent Reaction)

71. 7.8 In light reaction: ETC generates ATP, NADPH, O2
1. Light energy is absorbed
2. Electrons excited
3. Energy from ETC used to make ATP and NADPH

72. WATER

73. #2 PS II: Breaking up water
The P680 requires an electron, which is taken from a water molecule, breaking the water into H+ ions and O-2 ions.
These form the O2 that is released.
2 H2O e- + 4H+

74. What process drives each?
NADPH forming
ATP forming
O2 formation
Redox and ETC
Chemiosmosis

75. NOTE: Final Electron Acceptor is
NADPH
Not Oxygen (Oxygen is given off) in Light Reaction of Photosynthesis

76. Animation
Making Oxygen (You’ll love the noises)
(I hate ‘em)

77. Chemiosmosis Again
#1 Remember chemiosmosis in cellular respiration, well, here it is again.

78. 7.9 Question #2 PS I: Forming H+ ions to form ATP
By chemiosmosis

79. 7.9 #3 There would now be more H+ ions located:
Came from the stroma and went to the thylakoid interior

80. 7.9 #4
The H+ ions move through what port to move back into the stroma?
ATP synthase

81. #5 Photophosphorylation
is the process of converting energy from a light-excited electron into the phosphate bond of an ADP molecule into ATP.
This occurs when the electrons from water are excited by the light in the presence of P680.

82. CALVIN CYCLE
Or the LIR

84. Can the Calvin Cycle also be called the “dark reaction?”
PEANUT: It does not need light to run, but it can also run during light. So…the “dark cycle” term is not used anymore.

85. Animation Noncyclic photophosphorylation
(THIS ONE IS MY FAVORITE) Cyclic and Noncyclic Photophosphorylation (first one is very detailed, second one is better for HS)
Photosynthetic ETC and ATP Synthesis

86. View Me
Photosynthetic Electron Transport and ATP Synthesis

88. 7.10 #1 Calvin Cycle
Uses the CO2 (from the atmosphere) and ATP and NADPH (from light reactions) to run the sugar factory

89. Step 1: Carbon Fixation
RUBISCO ENZYME combines 3 molecules of CO2 with ribulose bisphosphate (5-C) RuBP makes 6-C

90. #2 G3P “Glyceraldehyde- 3 phosphate”
the energy-rich molecule made in the Calvin cycle
it can be used to make glucose or other organic molecules

91. The enzyme rubisco combines with CO2 to form 3-C molecule, 3PGA#3
The enzyme rubisco combines with CO2 to form 3-C molecule, 3PGA

92. It takes 6 turns to make one glucose molecle#4
It takes 6 turns to make one glucose molecle

93. Regeneration of RuBP
Energy from ATP is used to reform RuBP molecules (hey, its recyclable!)

94. Occurs in stroma of chloroplasts
Calvin Cycle
Occurs in stroma of chloroplasts

95. 7.11 Review of Photosynthesis

96. Summary: Calvin Cycle

97. Overall Equation

98. QUIZ TIME: structures
The light reactions (LDR) of photosynthesis occur in the __________, and the Calvin cycle (LIR) occus in the __________ of the chloroplast.

99. ANSWER
The light reaction occurs in the thylakoid membranes and the dark reaction occurs in the stroma.

100. Which equation summarizes photosynthesis?
A. water + starch ---> glucose + glucose + glucose B. water + carbon dioxide ---> oxygen + glucose + water C. glucose + oxygen ---> water + carbon dioxide + ATP D. glucose + glucose ---> maltose + water

101. B. water + carbon dioxide ---> oxygen + glucose + water
ANSWER
B. water + carbon dioxide ---> oxygen + glucose + water

102. In what organelle does photosynthesis occur?
A. the nucleus B. chloroplasts C. the vacuole D. the cell wall

103. ANSWER
B. Chloroplast

104. QUESTION:
Four identical plants are grown under different colored light bulbs. Under which color will the release of oxygen gas be slowest? A. Green
B. blue C. orange D. red

105. ANSWER:
A. Green

106. QUIZ TIME The reason why ADP + P form ATP in thylakoid membranes is…
A movement of electrons between photosystem II and photosystem I.
B oxidation of water
C oxidation of NADPH
D absorption of photons by chloroplast pigments
E higher concentration of H+ inside versus outside the thylakoid membranes

107. ANSWER
E. a higher concentration of H+ ions inside vs. outside the thylakoid membranes

108. QUIZ TIME
Water is broken down and the electrons from water pass through photosystem II and photosystem I before adding e- to:
A carbon dioxide
B NADP+
C plastoquinones
D FAD
E rubisco

109. ANSWER
NADP+ to make higher energy NADPH

110. QUIZ TIME
Which of the following would have the smallest effect on the rate of photosynthesis in a green plant? A. carbon dioxide concentration B. light intensity C. oxygen concentration D. water available

111. C. oxygen concentration
ANSWER:
C. oxygen concentration

112. QUIZ TIME A. more concentrated with ATP
During photosynthetic electron transport, the interior compartment of the thylakoid membranes becomes:
A. more concentrated with ATP
B. more concentrated with H+ ions
C. less concentrated with H+ ions

113. HINT: Distribution of H+ ions
Light Rx
more inside
Dark Rx
Even in and out

114. More concentrated with H+ ions
ANSWER
More concentrated with H+ ions

115. QUIZ TIME
Which of the following is produced during photosynthesis? A. carbon dioxide B. lactic acid C. DNA D. PGAL

116. ANSWER
D. PGAL

117. QUIZ TIME
Atmospheric oxygen that is inhaled by animals comes from: A. carbon dioxide molecules split during the light reactions B. carbon dioxide split during the dark reactions C. water molecules split during the light reactions D. water molecules split during the dark reactions

118. C. water molecules split during the light reactions
ANSWER
C. water molecules split during the light reactions

119. QUIZ TIME
What change occurs during photosynthesis? A. solar energy is converted to chemical energy B. kinetic energy is converted to chemical energy C. chemical energy is converted to radiant energy D. water is converted to chemical energy

120. A. solar energy is converted to chemical energy
ANSWER
A. solar energy is converted to chemical energy

121. Cuticle Epidermis Guard cells Palisade Phloem Xylem Spongy Mesophyll Stomata Bundle Sheath

122. A=cuticle
B=Upper epidermis
C=Vein
D=Phloem
E=xylem
F=Palisade layer
G=spongy layer
H=guard cell
I=stomata

123. QUIZ TIME The overall source of energy for photosynthesis is:
A. energy from the sun
B. energy from ATP
C. energy when oxygen is produced

124. ANSWER
A. energy from the sun

125. QUIZ TIME
What three events occur during the light reactions of photosynthesis?
Forming ATP
NADP+ to NADPH
Fixing CO2
Releasing O2

126. ANSWER
Forming ATP
NADP+ to NADPH
Releasing O2

127. QUIZ TIME Which of the following does not happen in photosystem I?
ATP is produced
electron transport in the thylakoid membranes
light energy is used
NADPH is formed

128. HINT

129. ANSWER (which is NOT)
NADPH is formed

130. QUIZ TIME Where does the Calvin Cycle take place?
Thylakoid membranes of chloroplasts
Stroma of chloroplasts
Matrix of mitochondria
Inner membrane of mitochondria

131. Stroma of chloroplasts
ANSWER
Stroma of chloroplasts

132. What is the name of the enzyme that causes CO2 to form glucose?
QUIZ TIME
What is the name of the enzyme that causes CO2 to form glucose?
ATPase
glucosease
rubisco

133. ANSWER
rubisco

134. QUIZ TIME
What two high energy compounds are required for this reaction?
ATP
NADH
NADPH
ADP
FADH

135. ANSWER
ATP and NADPH

136. QUIZ TIME
What is the name of the process in which carbon dioxide is made into glucose?
Krebs cycle
Calvin cycle
Einstein cycle

137. ANSWER
CALVIN CYCLE
(or sometimes the Calvin-Bensen Cycle)

138. QUIZ TIME Which does NOT happen in the Dark Reaction: using ATP
using NADPH
using Carbon Dioxide
making water

139. ANSWER
MAKING WATER

140. QUIZ TIME What are the products of the dark reaction? ATP ADP glucose
NADP+

141. ANSWER
ADP
NADP+
glucose

142. QUIZ TIME The reason why ADP + P form ATP in thylakoid membranes is…
A movement of electrons between photosystem II and photosystem I.
B oxidation of water
C oxidation of NADPH
D absorption of photons by chloroplast pigments
E higher concentration of H+ inside versus outside the thylakoid membranes

143. ANSWER
a higher concentration of H+ ions inside vs. outside the thylakoid membranes

144. QUIZ TIME
During photosynthetic electron transport, the interior compartment of the thylakoid membranes becomes:
A. more concentrated with ATP
B. more concentrated with H+ ions
C. less concentrated with H+ ions

145. ANSWER
More concentrated with H+ ions

146. QUIZ TIME The overall source of energy for photosynthesis is:
A. energy from the sun
B. energy from ATP
C. energy when oxygen is produced

147. ANSWER
A. energy from the sun

148. QUIZ TIME
What three events occur during the light reactions of photosynthesis?
Forming ATP
NADP+ to NADPH
Fixing CO2
Releasing O2

149. ANSWER
Forming ATP
NADP+ to NADPH
Releasing O2

150. QUIZ TIME
What is the name of the process in which carbon dioxide is made into glucose?
Krebs cycle
Calvin cycle
Einstein cycle

151. ANSWER
CALVIN CYCLE
(or sometimes the Calvin-Bensen Cycle)