1. Photosynthetic Pigments

2. Bellwork
Plants grown in the shade often produce larger leaves than plants grown in full sunlight. Propose a hypothesis to explain this observation.

3. Learning Objectives List the stages of photosynthesis
Identify the site of photosynthesis in eukaryotes and prokaryotes
Identify the part of the visible light spectrum that chlorophyll and cartenoids absorb
Explain how paper chromatography separates photosynthetic pigments in a leaf extract

4. Key Terminology Photosynthetic pigments Paper chromatography
Stationary phase
Mobile phase

5. Photosynthesis
Chemical Reaction
CO2 + H20 + light C6H12O6 + O2

6. Stages of Photosynthesis
Absorption of sunlight
Stage 2
Conversion of light energy to chemical energy in the form of ATP and NADPH
Light-dependent reactions
Stage 3
Synthesis of organic compounds, with CO2 as carbon source
light-independent reactions

7. Cellular site of photosynthesis
Chloroplasts
plant cells and algae
(eukaryotes)
Plasma membrane
photosynthetic bacteria
(prokaryotes)

8. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Explain why the site of photosynthesis is the plasma membrane not chloroplasts in photosynthetic bacteria.
3. Think-pair-share
teacher presents a question
teacher gives wait time for student to form answer
teacher instructs students to share their answer with a partner
teacher calls on non-volunteers to share with the class
PROPERTY OF PIMA COUNTY JTED, 2010 3 8

9. Stage 1: Absorption of Light
How does a leaf absorb light?
Through light-absorbing substances called pigments

10. Light Spectrum Visible Spectrum
Part of the spectrum that we see with our eyes
Photosynthetic pigments absorb in the visible spectrum

11. Classification of Pigments Two Major Groups
Chlorophyll
primary photosynthetic pigment
absorb in red and blue region of visible light spectrum
Reflects green
Carotenoids
absorb light of blue and blue-green wavelengths
reflects yellow, orange and red
aid chlorophyll in the absorption of light

12. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Why does a red rose appear the color red to your eyes?
3. Think-pair-share
teacher presents a question
teacher gives wait time for student to form answer
teacher instructs students to share their answer with a partner
teacher calls on non-volunteers to share with the class
PROPERTY OF PIMA COUNTY JTED, 2010 3 12

13. Identification of Plant Pigments
Photosynthetic pigments identified by a laboratory procedure known as paper chromatography.

14. Purpose of Chromatography
Separate components of a mixture through interaction with a stationary and mobile phase
Use paper chromatography to separate the photosynthetic pigments

15. Paper Chromatography
Stationary phase – paper
Mobile phase - solvent

16. How paper chromatography works
Place mixture at the origin of paper (Black dot)
Place the tip of the paper in a solvent
Solvent migrates up paper (solvent front)
Components that are soluble in the solvent will move with the solvent up the paper

17. Demonstration with Black Washable Marker
In the demonstration, identify the stationary phase, mobile phase
Identify which color was most soluble in the solvent, least soluble in the solvent

18. How components of mixture separate
Depends on their attraction to paper versus their solubility in the solvent
Example: Non-polar solvent
A component that carries a charge will be more attracted to the charged molecules (i.e. cellulose) in the paper than the solvent.
Consequently, it will stay close to the origin where the mixture was applied to the paper.

19. Demonstration with Black Washable Marker
Which color was most attracted to the chromatography paper? Explain.

20. Separation, therefore, depends on:
Solubility in the solvent (more soluble more it will move up the paper)
Attraction to the cellulose in the paper (more attracted to the paper will stay close to the origin)

21. Components of mixture identified by its Rf Value
Rf value = distance from origin to spot divided by distance from origin to solvent front
Rf value important when comparing chromatographs because that value stays constant for a particular component

22. Chromatogram

23. Calculation of Rf value
The solvent migrated 10 mm
Xanthophyll pigment migrated 4 mm
What was its Rf value?
So this pigment moved 0.4 as far as the solvent

24. Write a “snapshot” of today’s learning in 25 to 50 words.
teacher provides a prompt from the lesson
students must write a “snapshot” of the lesson in 25 words or less
teacher uses a strategy to check all 24