1. Tradescantia leaf

3. Photosynthesis Cellular Respiration
Energy Conversions
Photosynthesis
Cellular Respiration

4. Energy Conversion Energy: The ability to do work or cause motion
Potential E: “Stored Energy”; Energy of position
Kinetic Energy: Energy of motion
Chemical Energy: Potential Kinetic

7. Exothermic Vs Endothermic
Exothermic (Exergonic): Gives off heat
Examples: Fire; Cellular Respiration
Endothermic (Endergonic): Absorbs heat
Examples: Cold Pack, Photosynthesis

9. Photosynthesis Light Reaction Light-Dependent Reactions Calvin Cycle

10. Photosynthesis: in plants algae, Some protists some prokaryotes
Fig. 10-2
Photosynthesis:
in plants
algae,
Some protists
some prokaryotes
(a) Plants
Figure 10.2 Photoautotrophs
10 µm
(c) Unicellular protist
(e) Purple sulfur
bacteria
1.5 µm
(b) Multicellular alga
(d) Cyanobacteria
40 µm

11. Structures of Photosynthesis
Chloroplasts are structurally similar to photosynthetic bacteria
Leaves are the main area of Photosynthesis
Their green color is from chlorophyll, the green pigment
CO2 enters and O2 exits the leaf through pores called stomata

12. Fig. 10-3a
Leaf cross section
Vein
Chloroplasts are found in cells of the mesophyll, the interior tissue of the leaf
A typical mesophyll cell has 30–40 chloroplasts
Thylakoid
Grana
Stroma
Mesophyll
Stomata
CO2 O2
Chloroplast
Mesophyll cell
Figure 10.3 Zooming in on the location of photosynthesis in a plant
5 µm

13. Component of a Chloroplast
Thylakoid –
Saclike photosynthetic membranes
Light-dependent reactions occur here
Granum / Grana:–
Stack of thylakoids
Stroma –
Region outside the thylakoid membrane
Reactions of the Calvin Cycle occur here

14. The Photosynthesis Equation
6 CO H2O + Light energy  C6H12O6 + 6 O2 + 6 H2O

15. Reactants: 6 CO2 12 H2O Products: C6H12O6 6 H2O 6 O2
Fig. 10-4
Reactants:
6 CO2
12 H2O
Products:
C6H12O6
6 H2O
6 O2
Figure 10.4 Tracking atoms through photosynthesis

16. Calvin cycle Light-dependent reactions Occurs in stroma
Occurs in Thylakoid
Used H2O and light to produce ATP, NADPH, and O2
NADPH is an electron carrier
Calvin cycle
Occurs in stroma
uses carbon dioxide, ATP, and NADPH to produce sugars

17. Photosynthesis Goal? – What is it?
Needs Energy:
Photophosphorylation –
The production of ATP using energy from an electron transport chain.

18. Photosynthesis Photosynthesis: The Calvin cycle
Light reactions (the photo part)
Calvin cycle (the synthesis part)
The light reactions:
(in the thylakoids):
Split H2O
Release O2
Reduce NADP+ to NADPH
Generate ATP from ADP by photophosphorylation
The Calvin cycle
(in the stroma) forms sugar from CO2, using ATP and NADPH
The Calvin cycle begins with carbon fixation, CO2 into organic molecules

19. i Light NADP+ ADP Light Reactions Chloroplast H2O + P
Fig
H2O
Light
NADP+
ADP + P i
Light
Reactions
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
Chloroplast

21. i Light NADP+ ADP Light Reactions ATP NADPH Chloroplast O2 H2O + P
Fig
H2O
Light
NADP+
ADP + P i
Light
Reactions
ATP
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
NADPH
Chloroplast O2

22. i CO2 Light NADP+ ADP Calvin Cycle Light Reactions ATP NADPH
Fig
H2O
CO2
Light
NADP+
ADP + P i
Calvin
Cycle
Light
Reactions
ATP
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
NADPH
Chloroplast O2

23. i CO2 Light NADP+ ADP Calvin Cycle Light Reactions ATP NADPH
Fig
H2O
CO2
Light
NADP+
ADP + P i
Calvin
Cycle
Light
Reactions
ATP
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
NADPH
Chloroplast
[CH2O]
(sugar) O2

24. Fig. 10-7
The light reactions convert solar energy to the chemical energy of ATP and NADPH
Light
Chloroplasts are solar-powered chemical factories
Their thylakoids transform light energy into chemical energy:
ATP
NADPH
Reflected
light
Chloroplast
Absorbed
light
Granum
Transmitted
light
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

26. jj jj jj jj

29. Sunlight Light is a form of electromagnetic energy
The electromagnetic spectrum is the entire range of electromagnetic energy, or radiation
Visible light consists of wavelengths (including those that drive photosynthesis) that produce colors we can see
Wavelength is the distance between crests of waves
Wavelength determines the type of electromagnetic energy

30. 1 m (109 nm) 10–5 nm 10–3 nm 1 nm 103 nm 106 nm 103 m Micro- waves
Fig. 10-6
1 m
(109 nm)
10–5 nm
10–3 nm
1 nm
103 nm
106 nm
103 m
Gamma
rays
Micro-
waves
Radio
waves
X-rays UV
Infrared
Visible light
Figure 10.6 The electromagnetic spectrum
380
450
500
550
600
650
700
750 nm
Shorter wavelength
Longer wavelength
Higher energy
Lower energy

31. Light and Pigments Pigments – light absorbing chemicals Chlorophyll
Chlorophyll a
Chlorophyll b
Carotenoids
Xanthophyll

32. Why do leaves change colors?
Chlorophyll a
Chlorophyll b

33. Let’s break it down a little further …

34. NADP+ + e- + Energy  NADPH
(Nicotinamide adenine dinucleotide phosphate)
Electron, hydrogen, and energy carrier

35. Light-Dependant Reactions (Dark Rxn.)

36. 1. Photosystem II
Chlorophyll absorbs light
Electrons on a chlorophyll molecule (p680) absorb energy (become excited) are “energized”
High-energy electrons are passed on to the electron transport chain
Chlorophyll’s electrons are replenished by the breakdown of H2O

37. 2. Electron Transport Chain
The molecules of the electron transports chain use high-energy electrons to push H+ ions from the stroma into the inner thylakoid space.

38. 3. Photosystem I
Chlorophyll absorbs light-energy and re-energized the electrons from photosystem II.
NADP+ picks up these high-energy electrons and H+ to become NADPH.

40. 4. Hydrogen Ions Chemiosmosis = Electrochemical Gradient
Hydrogen ions build up inside the thylakoid membrane.
High concentration of H+ inside the membrane (Strong Positive Charge)
Low concentration of H+ outside the membrane (Negative Charge)
Provides the energy to form ATP

41. 5. ATP formation H+ try to reach equilibrium.
Pass through the ATP synthase
Movement of H+ ions through the ATP synthase powers ATP production

42. Calvin Cycle

43. The Calvin Cycle 6 CO2 molecules enter the cycle.
Enzyme “rubisco” (RuBP) forms 3-carbon molecules
ATP and NADPH form the High energy 3-Carbon molecules (G3P)
2 (G3P)are combined to form a 6-carbon sugar

44. Calvin Cycle

45. Factors Affecting Photosynthesis
Water supply
Amount of sunlight
Temperature

46. Types of Photosynthesis
C3 Photosynthesis
C4 Photosynthesis
CAM Photosynthesis

47. C3 Plants (Most Plants) Stomata are open during the day.
Called C3 because the CO2 is first incorporated into a 3-carbon compound.
Stomata are open during the day.
Photosynthesis takes place throughout the leaf.
Adaptive Value: more efficient than C4 and CAM plants under cool and moist conditions and under normal light because requires less machinery (fewer enzymes and no specialized anatomy)

48. C4 plants
Called C4 because the CO2 is first joined to make a 4C compound.
Stomata are open during the day
Adaptive Value:
Photosynthesizes faster than C3 plants
Can take HEAT and intense sunlight
Better water use enzymes brings in CO2 faster and so does not need to keep stomata open as much (less water lost by transpiration) for the same amount of photosynthesis.
Examples: four-wing saltbush, corn, and many of our summer annual plants.

49. CAM Plants:
CAM stands for Crassulacean Acid Metabolism
Stomata open at night (when evaporation rates are usually lower)
During the day, the acid is broken down and the CO2 is released to RUBISCO for photosynthesis
Adaptive Value:
Better Water Use Efficiency than C3 plants under dry conditions due to opening stomata at night when transpiration rates are lower (no sunlight, lower temperatures, lower wind speeds, etc.).
Examples: CAM plants include many succulents such as cactuses and agaves and also some orchids and bromeliads

51. Cellular Respiration

52. Cellular Respiration
Transforming the “potential” energy in food into chemical energy cells can use: ATP
CR = same way in plants and animals.
Overall Reaction:
C6H12O6 + 6O2 → 6CO2 + 6H2O

53. Cellular Respiration Overview
Breakdown of glucose starts in the cytoplasm:
At this point life diverges into two forms and two pathways
Anaerobic respiration = fermentation
Aerobic cellular respiration = High amounts of ATP

54. C.R. Reactions Glycolysis
Glucose molecule broken down into two 3-carbon molecules called pyruvate
Process is ancient / all organisms from simple bacteria to humans perform it the same way
Yields 2 ATP molecules for every one glucose molecule broken down
Yields 2 NADH per glucose molecule

56. Anaerobic Cellular Respiration
Some organisms thrive in environments with little or no oxygen
Marshes, bogs, gut of animals, sewage treatment ponds
No oxygen used = anaerobic
Results in no extra ATP
ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogens
End products: Alcohol or Lactic Acid:
YEAST & PLANTS: Ethanol and CO2 in beer/bread
MUSCLE CELLS: Lactic Acid

58. Aerobic Cellular Respiration
Oxygen required = aerobic
2 more sets of reactions which occur in a specialized structure within the cell called the mitochondria
1. Kreb’s Cycle
2. Electron Transport Chain

59. Kreb’s Cycle Completes the breakdown of glucose
Pyruvate 3-C broken down, the carbon and oxygen atoms end up in CO2 and H2O
Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2
Production of only 2 more ATP but loads up the coenzymes with H+ and electrons which move to the 3rd stage

61. Electron Transport Chain
Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase).
As electrons drop down stairs, energy released to form a total of 32 ATP
Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water

64. Energy Tally 36 ATP for aerobic 2 ATP for anaerobic vs.
Glycolysis ATP
Kreb’s ATP
Electron Transport 32 ATP
36 ATP
Anaerobic organisms can’t be too energetic but are important for global recycling of carbon

68. Comparing Photosynthesis & Respiration
Cellular Respiration
Function
Energy Storage
Energy Release
Location
Chloroplasts
Mitochondria
Reactants
CO2 and H2O
C6H12O6 and O2
Products
Equation
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6 + 6O2
6CO2 + 6H2O

69. Oxidation & Reduction Oxidation Reduction  adding O removing H
loss of electrons
releases energy
Exergonic
Reduction
removing O
adding H
gain of electrons
stores energy
Endergonic
C6H12O6
6O2
6CO2
6H2O
ATP  +
oxidation
reduction

72. LAB: Photosynthesis DPIP and Disks / Paul Anderson
~ (5:00 min)
DPIP = at 5:00 (for about 1 minute)

77. Redox Reactions
A chemical reaction involving the transfer of one or more elections from one reactant to another; also called oxidation/reduction reactions
In oxidation, a substance loses electrons, or is oxidized
In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)

78. becomes oxidized (loses electron) becomes reduced (gains electron)
Fig. 9-UN1
becomes oxidized
(loses electron)
becomes reduced
(gains electron)

79. becomes oxidized becomes reduced
Fig. 9-UN2
becomes oxidized
becomes reduced

80. Reverse Process of Each Other
Oxidative phosphorylation O2 reduced to H2O using electrons donated by NADH or FADH2 (Respiration)
Photophosphorylation just the reverse, H2O oxidized to O2 with electrons accepted (Photosynthesis)

81. The Light-Dependent Reactions
Photophosphorylation is the process of creating ATP using a Proton gradient created by the Energy gathered from sunlight.
Chemiosmosis is the process of using Proton movement to join ADP and P.

82. Do Now What is the function of NADPH?
How is light energy converted into chemical energy during photosynthesis?
Can the complete process of photosynthesis take place in the dark? Explain your answer.