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 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. Importance of ATP
Principal Compound Used To Store Energy In Living Organisms. Most energy stored between the last 2 phosphate bonds

10. 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

11. 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

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

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

14. History of Photosynthesis & Plant Pigments

15. 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

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

17. 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?

18. 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

19. A candle requires oxygen to burn
A candle requires oxygen to burn. Can you think of an experimental design that would prove plants make oxygen?

20. 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.

21. Repeated Priestly experiment with & without sunlight
1779
Repeated Priestly experiment with & without sunlight

22. 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

23. Melvin Calvin 1948
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

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

25. The Photosynthesis Equation

26. 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

27. Light and Pigments
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

29. The Biochemical Reactions

30. It Begins with Sunlight!

31. Photoautotrophs Absorb Light Energy

32. Inside A Chloroplast

33. 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

35. Thylakoid membranes
Light Dependent reactions occur here

36. Photosynthesis Overview

37. Light Dependent Reactions
Occurs across the thylakoid membranes
Uses light energy
Produce Oxygen from water
Convert ADP to ATP

38. Light Dependent Reaction

39. Light Dependent Reaction

40. Oh it could get a whole lot more complicated folks!

41. Light Reaction Summary
Reactants:
H2O
Light Energy
Energy Products:
ATP
NADPH

42. The Calvin Cycle

44. Factors Affecting the Rate of Photosynthesis
Amount of available water
Temperature
Amount of available light energy