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-protist

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

10. 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

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

12. History of Photosynthesis & Plant Pigments

13. 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

15. The Photosynthesis Equation

16. 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

17. 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

18. 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

19. Magnesium atom at the center of chlorophyll
There are 2 main types of chlorophyll molecules:
Chlorophyll a
Chlorophyll b
Magnesium atom at the center of chlorophyll

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

22. 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

23. The Biochemical Reactions

24. It Begins with Sunlight!

25. Inside A Chloroplast

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

28. Thylakoid membranes Light Dependent reactions occur here
Photosystems are made up of clusters of chlorophyll molecules
Photosystems are embedded in the thylakoid membranes
The two photosystems are:
Photosystem I
Photosystem II

30. Function of the Stroma Light Independent reactions occur here
ATP used to make carbohydrates like glucose
Location of the Calvin Cycle

31. Photosynthesis Overview

32. Energy Carriers NADP+ = Reduced Form
Nicotinamide Adenine Dinucleotide Phosphate (NADP+)
NADP+ = Reduced Form
Picks Up 2 high-energy electrons and H+ from the Light Reaction to form NADPH
NADPH carries energy to be passed on to another molecule

33. Light Dependent Reactions
Occurs across the thylakoid membranes
Uses light energy
Produce Oxygen from water
Convert ADP to ATP
Also convert NADP+ into the energy carrier NADPH

34. Light Dependent Reaction

35. Light Dependent Reaction

36. Light Dependent Reaction

37. Photosynthesis Begins
Photosystem II absorbs light energy
Electrons are energized and passed to the Electron Transport Chain
Lost electrons are replaced from the splitting of water into 2H+, free electrons, and Oxygen
2H+ pumped across thylakoid membrane

38. Photosystem I
High-energy electrons are moved to Photosystem I through the Electron Transport Chain
Energy is used to transport H+ from stroma to inner thylakoid membrane
NADP+ converted to NADPH when it picks up 2 electrons & H+

39. Phosphorylation Enzyme in thylakoid membrane called ATP Synthase
As H+ ions passed through thylakoid membrane, enzyme binds them to ADP
Forms ATP

41. Light Reaction Summary
Reactants:
H2O
Light Energy
Energy Products:
ATP
NADPH
Molecular Product: O2

42. Light Independent Reaction
ATP & NADPH from light reactions used as energy
Atmospheric C02 is used to make sugars like glucose and fructose
Six-carbon Sugars made during the Calvin Cycle
Occurs in the stroma

43. 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

44. The Calvin Cycle

45. The Calvin Cycle
Two turns of the Calvin Cycle are required to make one molecule of glucose
3-CO2 molecules enter the cycle to form several intermediate compounds (PGA)
A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle

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

48. Increasing levels of CO2 will also cause the rate of photosynthesis to increase then level off.

49. Light independent Reaction Summary
Reactants:
CO2
Energy Products:
ADP + P
NADP+
Molecular Product:
C6H12O6 49