1. Photosynthesis
Energy & Life

2. Overview of Photosynthesis

3. Autotrophs
Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food.

4. Autotrophs Autotrophs include organisms that make their own food
Autotrophs can use the sun’s energy directly
Euglena

5. Heterotrophs
Heterotrophs are organisms that can NOT make their own food
Heterotrophs can NOT directly use the sun’s energy

6. Candles release energy as HEAT & LIGHT
Energy Takes Many Forms such as light, heat, electrical, chemical, mechanical
Energy can be changed from one form to another
Energy can be stored in chemical bonds & then released later
Candles release energy as HEAT & LIGHT

7. ATP – Cellular Energy Adenosine Triphosphate
Contains two, high-energy phosphate bonds
Also contains the nitrogen base adenine & a ribose sugar

8. One phosphate bond has been removed
ADP
Adenosine Diphosphate
ATP releases energy, a free phosphate, & ADP when cells take energy from ATP
One phosphate bond has been removed

9. Sugar in ADP & ATP
Called ribose
Pentose sugar
Also found on RNA

10. Importance of ATP
Principal Compound Used To Store Energy In Living Organisms

11. Releasing Energy From ATP
ATP is constantly being used and remade by cells
ATP provides all of the energy for cell activities
The high energy phosphate bonds can be BROKEN to release energy
The process of releasing ATP’s energy & reforming the molecule is called phosphorylation

12. Releasing Energy From ATP
Adding A Phosphate Group To ADP stores Energy in ATP
Removing A Phosphate Group From ATP Releases Energy & forms ADP
Loose
Gain

13. Cells Using Biochemical Energy
Cells Use ATP For:
Active transport
Movement
Photosynthesis
Protein Synthesis
Cellular respiration
All other cellular reactions

14. More on ATP Cells Have Enough ATP To Last For A Few Seconds
ATP must constantly be made
ATP Transfers Energy Very Well
ATP Is NOT Good At Energy Storage

15. Glucose Glucose is a monosaccharide C6H12O6
One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP

16. History of Photosynthesis & Plant Pigments

17. Photosynthesis
Involves the Use Of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

18. The Photosynthesis Equation

19. Investigating Photosynthesis
Many Scientists Have Contributed To Understanding Photosynthesis
Early Research Focused On The Overall Process
Later Researchers Investigated The Detailed Chemical Pathways

20. Early Questions on Plants
Several Centuries Ago, The Question Was: Does the increase in mass of a plant come from the air? The soil? The Water?

21. Van Helmont’s Experiment 1643
Planted a seed into A pre-measured amount of soil and watered for 5 years
Weighed Plant & Soil. Plant Was 75 kg, Soil The Same.
Concluded Mass Came From Water

22. Priestley’s Experiment 1771
Burned Candle In Bell Jar Until It Went Out.
Placed Sprig Of Mint In Bell Jar For A Few Days.
Candle Could Be Relit And Burn.
Concluded Plants Released Substance (O2) Necessary For burning.

23. Ingenhousz’s Experiment 1779
Repeated Priestly experiment with & without sunlight

24. Results of Ingenhousz’s Experiment
Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight.
Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen

25. Julius Robert Mayer 1845
Proposed That Plants can Convert Light Energy Into Chemical Energy

26. Samuel Ruben & Martin Kamen 1941
Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water
RUBIN
KAMEN

27. Melvin Calvin 1948 Does NOT require sunlight
First to trace the path that carbon (CO2) takes in forming Glucose
Does NOT require sunlight
Called the Calvin Cycle or Light Independent Reaction
Also known as the Dark Reaction

28. Rudolph Marcus 1992 Studied the Light Independent Reactions
First to describe the Electron transport Chain

29. The Photosynthesis Equation

30. Pigments
In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments
Chlorophyll is the primary light-absorbing pigment in autotrophs
Chlorophyll is found inside chloroplasts in the thylakoids

31. Light and Pigments Photon = Light Energy Unit
Energy From The Sun Enters Earth’s Biosphere As Photons
Photon = Light Energy Unit
Light Contains A Mixture Of Wavelengths
Different Wavelengths Have Different Colors

32. Light & Pigments
Different pigments absorb different wavelengths of light
Photons of light “excite” electrons in the plant’s pigments
Excited electrons carry the absorbed energy
Excited electrons move to HIGHER energy levels

33. Pigments There are 4 main types of pigment molecules: Chlorophyll a
Chlorophyll b
Xanthophyll
Carotenes

34. Chlorophyll a and b

35. Chlorophyll a Found in all plants, algae, & cyanobacteria
Makes photosynthesis possible
Participates directly in the Light Reactions
Can accept energy from chlorophyll b

36. Chlorophyll b Chlorophyll b is an accessory pigment
Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a
Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN

37. The Biochemical Reactions

38. It Begins with Sunlight!

39. Flow of Energy

40. Photoautotrophs Absorb Light Energy

41. Objectives
Summarize how energy is captured from sunlight in the first stage of photosynthesis.
Analyze the function of electron transport chains in the second stage of photosynthesis.
Relate the Calvin cycle to carbon dioxide fixation in the third stage of photosynthesis.
Identify three environmental factors that affect the rate of photosynthesis.

42. Key Terms Pigment Chlorophyll Carotenoid Thylakoid
Electron Transport Chain
NADPH
Carbon Dioxide Fixation
Calvin Cycle

43. Where does Photosynthesis occur?
Plants/Autotrophs – produce their own food (glucose)
Process called photosynthesis
Mainly occurs in the leaves:
a. stoma - pores
b. mesophyll cells-chloroplasts
found in this area
Mesophyll
Cell
Chloroplast
Stoma

45. Structure of the Chloroplast
Double membrane organelle
Outer membrane smooth
Inner membrane forms stacks of connected sacs called thylakoids
Thylakoid stack is called the granun (grana-plural)
Gel-like material around grana called stroma

46. Inside A Chloroplast

48. The 2 Stages of Photosynthesis
Stage 1-Light Reaction
Energy is captured from sunlight by chlorophyll and other pigments present.
Light energy is converted to chemical energy as water is split, which is temporarily stored in ATP & the energy carrier molecule NADPH and O2 gas is given off
Stage 2 -Light Independent Reaction/Dark Reaction/Calvin Cycle
The chemical energy stored in ATP & NADPH powers the formation of organic compounds from the combination of RuBP and the CO2 to eventually makes Glucose.

49. Stages of Photosynthesis
RuBP
Celluslose

50. The Photosynthesis Equation
Light
6CO H20 C6H12O O2
Carbon Dioxide
Water
Sugars
Oxygen
(High Energy)

51. Photosynthesis Overview

52. Function of the Stroma
Light Independent (DARK,CALVIN) reactions occur here
ATP used to make carbohydrates like glucose
Location of the Calvin Cycle

53. Light Dependent Reaction

54. Light Dependent Reaction

56. The Calvin Cycle

58. Factors Affecting the Rate of Photosynthesis
Amount of available water
Temperature
Amount of available light energy pH
Quantity and combination of pigments