1. CO2 + H2O --sun--> C6H12O6 + O
PHOTOSYNTHESIS
(rap)
CO2 + H2O --sun--> C6H12O6 + O

2. Examples of Photoautotrophs
Capture sunlight energy and use it to carry out photosynthesis
Phytoplankton - the first step in ocean food chains
Plants
Some bacteria
Many protistans

3. 2 types of organisms: autotrophs Heterotrophs Carbon source is:
Energy source is:
Heterotrophs
Carbon + Energy source are:
carbon dioxide
sunlight
autotrophs! yum

4. Photosynthesis Cellular Respiration SUN energy SUGAR energy
ATP energy

6. Photosynthesis Equation
LIGHT ENERGY
12H2O + 6CO2
6O2 + C6H12O6 + 6H2O
water
carbon dioxide
oxygen
glucose
water
(note: copy on top of pp)

7. Let’s Balance This Equation !6 6 6
___CO2 + ___H20  ___C6H12O6 + ___O2
The product of photosynthesis is GLUCOSE 1

8. inputs and outputs of the photosynthetic process.

10. Can affect rate of Photosynthesis
Amount of
Carbon
Light
Temperature

11. Leaves and Leaf Structure
Plants are the only photosynthetic organisms to have _______ (and not all plants have leaves).
A leaf may be viewed as a solar collector crammed full of photosynthetic cells.
leaves

12. Leaf Structure UPPER EPIDERMIS cuticle PALISADE MESOPHYLL xylem SPONGY
phloem
LOWER
EPIDERMIS
AIR SPACES
CO2
one stoma O2

13. Tiny pores UNDER leaf  Stomata
CO2
Allows ____________ in
Allows ___________ out
Allows___________ out
K+ and H20 O2
H2O
<<LINK>>
K+ and H20

15. What Causes Stomata to Open?
to close:

17. A. CHLOROPLAST STRUCTURE
The number of chloroplasts in a cell varies from 20 – 100.
THIS IS THE ORGANELLE THAT DOES PHOTOSYNTHESIS

18. Organelles of photosynthesis
Chloroplasts
Organelles of photosynthesis
stroma
Two membranes
granum
thylakoid

19. What is the structural unit of photosynthesis?
WHERE LIGHT REACTION TAKES PLACE
Thylakoids are stacked like pancakes in stacks known collectively as .
The aeas between grana are referred to as?
DARK REACTION TAKES PLACE HERE
thylakoid
grana
stroma

20. STROMA
THYLAKOID
GRANA
INTERMEMBRANE
INNER
OUTER

22. A. THE NATURE OF LIGHT What IS sunlight??? wavelengths
Green plants use sunlight for photosynthesis
Light energy is in form of
Light travels in “bundles” called
What IS sunlight???
Sunlight = mixture of different wavelengths of light; many are visible to the eye
(VISIBLE LIGHT SPECTRUM).
wavelengths
photons

24. Electromagnetic Spectrum
Shortest Most Gamma rays
wavelength energy X-rays
UV radiation
Visible light
Infrared radiation
Microwaves
Longest Least Radio waves
wavelength energy

25. Visible Light long waves short waves low energy high energy V I B G Y
10-5nm 10-3nm 1nm nm nm nm
1 m m V I B G Y O R

26. So, what IS a pigment??
Molecules that have evolved to absorb wavelengths in the visible region of the spectrum very well

27. Chlorophyll
________________, the green pigment common to all photosynthetic cells
absorbs all wavelengths of visible light EXCEPT GREEN, which it REFLECTS to be detected by our eyes.
Black pigments all of the wavelengths that strike them.
White pigments/lighter colors all or almost all of the energy striking them.
absorb
reflect

28. CHLOROPHYLL - pigment found in green plant
Chlorophyll a –
(primary pigment); directly involved in the light dependent reactions
Chlorophyll b -
(accessory pigment); helps capture sunlight and transfer energy to chlorophyll a

29. a) Chlorophyll does not absorb most yellow and green light – these colors are reflected
b) Chlorophyll b absorbs light with wavelengths of 480 nm (blue) and 650 nm (red) (more blue/less red)
c) Chlorophyll a - absorbs light within wavelengths of 435 nm (blue) and 675 nm (red) (less blue/more red than Chl.b)

31. 4. ACCESSORY Pigments
- Pass their absorbed sunlight energy to chlorophyll, which passes the energy to the photosynthetic pathway. For this reason they are called “accessory” pigments
Carotenoids – carotene & Xanthophylls
Anthocyanins
Phycobilins

32. Why do plants need accessory pigments?
To utilize ALL wavelengths of light entering plant

33. a) Carotene – reflect yellow, red and
a) Carotene – reflect yellow, red and orange; 450 nm and 500 nm; absorb blue and green.
They are not water soluble.
Found in carrots, oranges and autumn leaves

34. b) Xanthyphylls – reflect yellow and orange
c)Anthocyanins - responsible for the red, purple, and blue colors of many fruits, vegetables, cereal grains, and flowers.

35. Overview of Photosynthesis
equation:
6CO2 + 12H2O > C6H12O6+ 6O2 + 6H2O
Chlorophyll
Light
In two stages. . .

37. Stage 1 – Light Dependent Reactions
Water is split into hydrogen ions (H+), electrons and oxygen (O2)
The O2 diffuses out of the chloroplasts (by-product)
The light energy is converted to chemical energy, which is temporarily stored in ATP and NADPH

38. Stage 2 – Calvin Cycle (light independent rxn)
The chemical energy stored in ATP and NADPH powers the formation of organic compounds (sugars), using carbon dioxide (CO2)

39. (thylakoid membrane) stroma The Light Reactions occur in the
the Dark Reactions occur in the
stroma

40. A. Light Dependent Reaction
1. splits H2O into H+ (proton), electron(-) and O2
2. forms ATP
3. forms NADPH
4. releases O2

41. Action of Photosystem I And II

42. The high energy electrons leave the chlorophyll and travel to a:
Light energy strikes the: Electrons of specialized chlorophyll molecules in Photosystem (Ps II) absorb the energy and become “ ” (raised to a higher energy level.
The high energy electrons leave the chlorophyll and travel to a:
primary electron acceptor.
chlorophyll
excited

43. electron transport chain
The primary acceptor donates the electrons to a series of molecules (electron acceptors) in an As they do, the energy level of the electrons is reduced. The energy released is used to move into the thylakoids.
4. At the same time, Photosystem I (Ps I) absorbs light energy, raising the energy level of the electrons in chlorophyll again. These electrons are replaced by the electrons from Photosystem II (Ps II).
electron transport chain H+

44. 5. These “excited” electrons are passed to a different primary electron acceptor and then through another ETC. These electrons are moved to the stroma side of the membrane.
6. The energy and electrons are then combined with a H+ proton and NADP+ forming NADPH

45. Pigments in a Photosystem
reaction center
(a specialized chlorophyll a molecule)

46. released into atmosphere
The electrons from Photosystem I & II must be replaced. The source of electrons is the splitting of (HYDROLYSIS):
2 H2O H e- + O2
What happens to the oxygen??
water
released into atmosphere

47. NADPH
NADP+ + H+ H+ H+ H+

48. PRODUCTION OF ATP = A process called
chemiosmosis
8. Chemiosmosis relies on a concentration gradient of protons (H+) across the thylakoid membrane.
9. Where do we get these H+ protons??
produced from:
other protons are pumped into the thylakoid
the breakdown of water molecules

49. 10. Both these mechanisms act to build up a concentration gradient of protons (H+). The concentration of protons (H+) is higher in the ____________________ than in the stroma.
11. The protons (H+) can only pass through special protein channels of ATP synthase, thus converting ADP + P to __________
thylakoid
ATP

51. It’s a CYCLE ! autotrophs heterotrophs Photosynthesis
Energy-storing pathway
Releases oxygen
Requires carbon dioxide
Aerobic Respiration
Energy pathway
oxygen
carbon dioxide
releasing
Requires
Releases

52. Lecture 6.2 – Light Independent Reaction
aka – Dark Reaction
= Carbon Fixing Cycle
= Calvin-Benson Cycle
= C3 Pathway

53. The reactions in this process were worked out by Melvin Calvin, 1961.

54. Light-Independent Reactions (DARK)
Synthesis part of photosynthesis
Makes: From:
Can proceed in the OR LIGHT
Take place in the
CO2
GLUCOSE
dark
stroma

55. ribulose biphosphate (RuBP).
The Calvin Cycle occurs in the stroma of chloroplasts
where would it occur in a prokaryote?
Carbon dioxide is captured by the chemical –
-C carb compound.
How many molecules of CO2 will enter cycle to yield one molecule of glucose??
cytoplasm
ribulose biphosphate (RuBP). 5 6
C6H12O6

56. A. Summary ATP light reaction CO2 H carbohydrates stroma
Energy from _______ from ____________ is used to combine ________ from air with ___ from NADPH from light reaction to make ________________ .
12 NADPH + 18 ATP + 6CO C6H12O6 (glucose) + 12 NADP+18P + 6 H2O
The “Dark” phase takes place in the
light reaction
CO2 H
carbohydrates
stroma

57. B. PROCESS: CALVIN CYCLE (Carbon Fixation)
CO2 diffused into the chloroplasts and combines with a 5-C sugar (RuBP ribulose biphosphate) to form an unstable 6-C sugar. The enzyme required for this reaction
2. 6-C sugar immediately splits into 2 3-C compounds ( )
3. PGA combines with H from NADPH to form a 3-C sugar ( )
ribulase
PGA – phosphoglycerate
PGAL phosphoglyceraldehyde

58. Some G3P (PGAL) is converted to ; most is used toward building more ;
1 turn  ______ ATP
_______ NADPH
________ CO2
How many turns to make a GLUCOSE?
5. Energy for reactions comes from _________
6. ____________ is produced as a by-product
glucose
RuBP 3 2 1 6
ATP
Water

59. NOTE: Glucose is not a direct product of photosynthesis.
The 3-C compound PGAL produced are combined to form starch
may later be converted to sucrose The sucrose and starch are converted to glucose for cellular respiration

60. Calvin-Benson Cycle Overall products Overall reactants Carbon dioxide
ATP
NADPH
Overall products
Glucose
ADP
NADP+
Reaction pathway is cyclic and RuBP
(ribulose bisphosphate) is regenerated

61. A CYCLE SAVES:
E N E R G Y

62. sucrose starch The most easily transported plant carbohydrate
Phosphorylated glucose is the building block for:
sucrose
The most easily transported plant carbohydrate
starch
The most common storage form
<<LINK>>
what happens to glucose?

63. CO2
RuBP
PGA
ATP
ATP
NADPH
PGAL
sugar

64. diffusion through stomata
BACKGROUND:
How does CO2 enter autotrophic cells?
Land plants must guard against drying out (desiccation) and so have evolved specialized structures known as:
to allow gas to enter and leave the leaf.
diffusion through stomata
stomata

65. The C3 Pathway the C3 pathway a three-carbon PGA
What is the first stable molecule made?
Because the first intermediate has three carbons, the pathway is called
the C3 pathway
a three-carbon PGA

66. C3 Plants in HOT WEATHER On hot, dry days stomata close Inside leaf
Oxygen levels ?
Carbon dioxide levels ?
RuBP attaches to _______ instead of carbon dioxide
Only one PGAL forms instead of two
oxygen

67. C4 and CAM pathways are “PRE-CYCLES”
They get molecules PREPARED to enter the normal dark cycle if conditions are unfavorable

68. C4 Plants
CO2 C4
CO2 C3

69. CAM Plants
CO2
CAM
CO2 C3

70. C3 C4 CAM Ex.-Pineapple, cactus… Stores 4C molecule until daytime CO2
+ PEP (3-C)
= 4-C molecule
Ex.-Corn, sugarcane…
Stores 4C molecule in separate cells from cycle
CO2
+ PEP (3-C)
= 4-C molec
CO2
+ RuBP (5-C)
= two 3-C molecules
Ex.-Pineapple, cactus…
Stores 4C molecule until daytime